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1
Prakoso, Widjojo Adi. "Lower Bound Capacity of Strip Footings on Rock Masses with Two Discontinuity Sets." Indonesian Geotechnical Journal 1, no. 2 (August 30, 2022): 1–11. http://dx.doi.org/10.56144/igj.v1i2.10.
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This paper presents a lower bound model for predicting the rock strip footing bearing capacity. The model is based on strip footings on rock masses with two sets of ubiquitous, closed discontinuities. The model considers explicitly the strength of the intact rock and the discontinuities, as well as the number and orientation of the discontinuities. The validation of the model is presented. The parametric study of footings on rock masses with two discontinuity sets having the same strength is performed, and the results are reported graphically in detail. The bearing capacity is controlled primarily by the rock structures (number of discontinuity sets and orientation) and the discontinuity strength, and it is controlled by the intact rock strength for a very limited number of cases. The minimum bearing capacity factor is independent of the intact rock friction angle, but it is a linear function of discontinuity cohesion. The bearing capacity factor is also presented in terms of its ratio to UCS; the ratio for the maximum bearing capacity is rather insignificantly affected by intact rock friction angle, and not linearly correlated to discontinuity cohesion. The bearing capacity factor for rock masses with low discontinuity strengths tends to be more sensitive to any variation in discontinuity orientation. There are some exceptions to the above points, suggesting that there would always be some rock mass conditions leading to unexpected rock footing bearing capacities and therefore good characterization processes of rock masses would always be essential. The practical significant of this study is briefly discussed.
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Bolla, Alberto, Alberto Beinat, Paolo Paronuzzi, and Chiara Peloso. "Combined Field and Structure from Motion Survey to Identify Rock Discontinuity Sets of Aa Shallow Rockslide." IOP Conference Series: Earth and Environmental Science 906, no. 1 (November 1, 2021): 012103. http://dx.doi.org/10.1088/1755-1315/906/1/012103.
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Abstract The present work shows the results of a combined field and Structure from Motion (SfM) survey performed on the detachment surface of a shallow rockslide that occurred in the Rosandra Valley (Trieste, NE Italy), which was aimed at testing the use of 3D models obtained from Remote Sensing (RS) techniques to identify joint sets affecting unstable rock masses. According to discontinuity orientation data acquired from the field (N = 223), the investigated rock mass is affected by at least nine joint sets characterised by a notable variability. The extraction of joint sets from the 3D point cloud representing the surveyed rock outcrop was strongly sensitive to the point cloud density and the values of the controlling parameters of the density function embedded within the discontinuity extractor. This work demonstrates that, in order to properly identify rock joint sets, the exclusive application of a RS approach cannot fully substitute the traditional field survey, and the estimation of discontinuity sets should be integrated with joint orientation data acquired using a geological compass. To maximise its capabilities, the semi-automatic discontinuity set extraction from 3D point clouds should always be supported by a significant statistical sample of joint orientation measurements that are preliminarily collected from the field.
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Jimenez-Rodriguez, R., and N. Sitar. "A spectral method for clustering of rock discontinuity sets." International Journal of Rock Mechanics and Mining Sciences 43, no. 7 (October 2006): 1052–61. http://dx.doi.org/10.1016/j.ijrmms.2006.02.003.
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Gao, Feng, Dapeng Chen, Keping Zhou, Wenjing Niu, and Hanwen Liu. "A Fast Clustering Method for Identifying Rock Discontinuity Sets." KSCE Journal of Civil Engineering 23, no. 2 (December 17, 2018): 556–66. http://dx.doi.org/10.1007/s12205-018-1244-7.
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Jimenez, R. "Fuzzy spectral clustering for identification of rock discontinuity sets." Rock Mechanics and Rock Engineering 41, no. 6 (November 13, 2007): 929–39. http://dx.doi.org/10.1007/s00603-007-0155-6.
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Kulatilake, Pinnaduwa H. S. W. "3-D Rock Mass Strength Criteria—A Review of the Current Status." Geotechnics 1, no. 1 (August 8, 2021): 128–46. http://dx.doi.org/10.3390/geotechnics1010007.
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The presence of complex discontinuity patterns, the inherent statistical nature of their geometrical parameters, the uncertainties involved in the estimation of the discontinuity geometrical and geo-mechanical properties and complex three dimensional (3-D) in-situ stress make the accurate prediction of rock mass strength a difficult task. It has been a great challenge for the rock mechanics and rock engineering professions to develop a rock mass strength criterion in three dimensions that incorporates the effect of the minor and intermediate principal stresses and captures the scale dependent and anisotropic properties resulting from the discontinuity geometry parameters, such as the number of discontinuity sets, 3-D discontinuity intensity, and the distributions of the discontinuity orientation and size. Rock mechanics and rock engineering researchers have dealt with this topic for more than 55 years. The paper provides a critical review of the current state of the art regarding 3-D jointed rock mass strength criteria. The shortcomings of several rock mass strength criteria are discussed. The historic development of rock mass strength criteria that incorporate the effect of the minor and intermediate principal stresses and capture the scale dependent and anisotropic properties is presented. The most advanced 3-D rock mass strength criteria currently available in the literature are presented, including suggested future improvements.
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Slob, Siefko, Bart van Knapen, Robert Hack, Keith Turner, and John Kemeny. "Method for Automated Discontinuity Analysis of Rock Slopes with Three-Dimensional Laser Scanning." Transportation Research Record: Journal of the Transportation Research Board 1913, no. 1 (January 2005): 187–94. http://dx.doi.org/10.1177/0361198105191300118.
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Three-dimensional (3D) laser scanning data can be used to characterize discontinuous rock masses in an unbiased, rapid, and accurate manner. With 3D laser scanning, it is now possible to measure rock faces whose access is restricted or rock slopes along highways or railway lines where working conditions are hazardous. The proposed method is less expensive than traditional manual survey and analysis methods. Laser scanning is a relatively new surveying technique that yields a so-called point cloud set of data; every single point represents a point in 3D space of the scanned rock surface. Because the density of the point cloud can be high (on the order of 5 mm to 1 cm), it allows for an accurate reconstruction of the original rock surface in the form of a 3D interpolated and meshed surface using different interpolation techniques. Through geometric analysis of this 3D mesh and plotting of the facet orientations in a polar plot, it is possible to observe clusters that represent different rock mass discontinuity sets. With fuzzy k-means clustering algorithms, individual discontinuity sets can be outlined automatically, and the mean orientations of these identified sets can be computed. Assuming a Fisher's distribution, the facet outliers can be removed subsequently. Finally, discontinuity set spacings can be calculated as well.
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Wu, Xiang, Fengyan Wang, Mingchang Wang, Xuqing Zhang, Qing Wang, and Shuo Zhang. "A New Method for Automatic Extraction and Analysis of Discontinuities Based on TIN on Rock Mass Surfaces." Remote Sensing 13, no. 15 (July 23, 2021): 2894. http://dx.doi.org/10.3390/rs13152894.
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Light detection and ranging (LiDAR) can quickly and accurately obtain 3D point clouds on the surface of rock masses, and on the basis of this, discontinuity information can be extracted automatically. This paper proposes a new method to automatically extract discontinuity information from 3D point clouds on the surface of rock masses. This method first applies the improved K-means algorithm based on the clustering algorithm by fast search and find of density peaks (DPCA) and the silhouette coefficient in the cluster validity index to identify the discontinuity sets of rock masses, and then uses the hierarchical density-based spatial clustering of applications with noise (HDBSCAN) algorithm to segment the discontinuity sets and to extract each discontinuity from a discontinuity set. Finally, the random sampling consistency (RANSAC) method is used to fit the discontinuities and to calculate their parameters. The 3D point clouds of the typical rock slope in the Rockbench repository is used to extract the discontinuity orientations using the new method, and these are compared with the results obtained from the classical approach and the previous automatic methods. The results show that, compared to the results obtained by Riquelme et al. in 2014, the average deviation of the dip direction and dip angle is reduced by 26% and 8%, respectively; compared to the results obtained by Chen et al. in 2016, the average deviation of the dip direction and dip angle is reduced by 39% and 40%, respectively. The method is also applied to an artificial quarry slope, and the average deviation of the dip direction and dip angle is 5.3° and 4.8°, respectively, as compared to the manual method. Furthermore, the related parameters are analyzed. The study shows that the new method is reliable, has a higher precision when identifying rock mass discontinuities, and can be applied to practical engineering.
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Liu, Tiexin, Jun Zheng, and Jianhui Deng. "A new iteration clustering method for rock discontinuity sets considering discontinuity trace lengths and orientations." Bulletin of Engineering Geology and the Environment 80, no. 1 (July 18, 2020): 413–28. http://dx.doi.org/10.1007/s10064-020-01921-9.
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Lukačić, H., M. Krkač, S. Bernat Gazibara, Ž. Arbanas, and S. Mihalić Arbanas. "Detection of geometric properties of discontinuities on the Špičunak rock slope (Croatia) using high-resolution 3D Point Cloud generated from Terrestrial Laser Scanning." IOP Conference Series: Earth and Environmental Science 1124, no. 1 (January 1, 2023): 012006. http://dx.doi.org/10.1088/1755-1315/1124/1/012006.
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Abstract Rock mass characterization is a very important part of engineering geological investigation. For a better understanding of the rock mass behaviour, it is crucially important to obtain as much as possible information about the discontinuity network, especially about orientation and the number of dominant discontinuity sets. The traditional methodology includes field mapping which dominantly produces a limited amount of data and consequently only a rough estimate about discontinuity network. To increase the number of measurements and to eliminate orientation bias, rock mass on the Špičunak rock slope in Gorski kotar, Croatia, was analysed using a combination of 3D Point Cloud and Textured Mesh Model generated from 3D Point Cloud by Poisson surface reconstruction. Both models were obtained from Terrestrial Laser Scanning. Two considerably different parts of a rock slope, with different weathering conditions and different degrees of fracturing were mapped. Discontinuities were mapped in the field and on the models using manual mapping techniques and semi-automated methods. Manual mapping on a 3D Point Cloud and Textured Mesh Model was done by Compass plugin and by Trace a polyline tool in Cloud Compare software version V2.12 and semi-automated mapping methods were done by Discontinuity Set Extractor and qFacet Fast Marching plugin for Cloud Compare software version V2.12. This study was used to show how the application of different methodologies, for the detection of geometric properties of discontinuities, influences the result. Statistical analyses were performed on the collected data to determine differences in the accuracy between the mapping techniques. Manual mapping on the 3D Point Cloud and high-resolution Textured Mesh Model showed good agreement with field measurements, apart from the higher number of discontinuities mapped by remote sensing methods. On the other hand, significant deviations were found between manual and semi-automated mapping techniques. Semiautomated methods did not correctly detect certain discontinuities, especially bedding planes that are perpendicular to a rock face. Also, semi-automated methods overestimate the number of discontinuity sets, especially in a highly weathered and highly fractured rock mass. These differences between methods can influence kinematic analysis results. Based on the results, an appropriate methodology was proposed to utilize the advantages of both manual and semiautomated methods. The proposed approach presents a powerful tool to accurately map and measure discontinuity orientation with results comparable to the field measurements.
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Qiao, Lan, Nai-Fu Deng, Qing-Wen Li, Qing-Long Zhang, and Jia-Wang Hao. "Multi-CrackNet: A Fast Segmentation and Quantification Combined Method for Rock Discontinuity Traces by Capturing an Image." Geofluids 2022 (November 12, 2022): 1–22. http://dx.doi.org/10.1155/2022/1832662.
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Discontinuity investigation and characterization onsite is a labor-dependent work because current techniques cannot precisely handle multiple discontinuity identifications automatically under different work conditions. This paper proposes the multi-CrackNet which enables us to identify and segment linear discontinuities (joints and cracks) for random types of rock surface. A modified feature extraction network called the multiscale feature fusion pyramid network (MFFPN) has been developed based on FPN to capture and fuse more sensitive texture features of cracks across different types of background. With the help of a new training scheme by setting up 3 stages of training to simulate the human-based learning process, the established model can learn more features steadily and robustly from well-labelled databases. Additionally, a hybrid pixel-level quantification method is proposed to automatically compute the length, width, and inclination of cracks. Results show that the proposed method can achieve a detection accuracy of 87.1% for 1 to 9 sets of cracks on the rock surface across different types of rock. Case studies in Anshan West are provided to verify the reliability and accuracy of our method in macrolinear discontinuity identification and quantification, which sees great potentials in site investigation by saving a large amount of labor force.
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Liu, Jie, Xing-Dong Zhao, and Zeng-he Xu. "Identification of rock discontinuity sets based on a modified affinity propagation algorithm." International Journal of Rock Mechanics and Mining Sciences 94 (April 2017): 32–42. http://dx.doi.org/10.1016/j.ijrmms.2017.02.012.
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Albarelli, D. S. N. A., O. C. Mavrouli, and P. Nyktas. "Identification of potential rockfall sources using UAV-derived point cloud." Bulletin of Engineering Geology and the Environment 80, no. 8 (June 5, 2021): 6539–61. http://dx.doi.org/10.1007/s10064-021-02306-2.
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AbstractRecent advances in remote sensing techniques and computer algorithms allow accurate, abundant, and high-resolution geometric information retrieval for rock mass characterization from 3D point clouds. The automatic application of the extracted information for local scale rockfall susceptibility assessment, where discontinuities characteristics play a major role in rocky slope stability, requires step by step logical procedures. This paper presents a novel methodology to use the extracted discontinuity set characteristics for a local scale rockfall susceptibility assessment, tailored for Uncrewed Aerial Vehicle (UAV) data acquisition. The method consists of 4 steps: (i) 3D slope model reconstruction using UAV digital photogrammetry, (ii) automatic characterization of discontinuity sets, (iii) slope stability analysis, and (iv) susceptibility assessment using a new Rockfall Susceptibility Index. The proposed method was applied to a road cut rocky slope in a mountainous area of the Samaria National Park, in Crete Island, Greece. Visual validation indicates that the areas of higher and moderate rockfall susceptibility on the 3D model of the rocky slope are adjacent to rockfall source areas marked by the presence of fallen blocks on the foot of the slope. The proposed methodological workflow presents novelties related to the use of point clouds for the estimation of the Rock Quality Designation (RQD) index, the visualization of discontinuity set spacing, the evaluation of the persistence and the Slope Mass Rating (SMR) index, as well as the incorporation of the persistence of overhangs into the rockfall susceptibility assessment and visualization.
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Roslee, Rodeano, Jeffery Anak Pirah, Ahmad Nazrul Madri, and Mohd Fauzi Zikiri. "APPLICABILITY OF THE GEOLOGICAL STRENGTH INDEX (GSI) CLASSIFICATION FOR THE TRUSMADI FORMATION AT SABAH, MALAYSIA." Earth Science Malaysia 4, no. 1 (November 18, 2020): 77–81. http://dx.doi.org/10.26480/esmy.01.2020.77.81.
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During the feasibility and preliminary design stages of a project, when very little detailed information on the rock mass and its geomechanic characteristics is not available, the use of a Rock Mass Classification Scheme (RMCS) can be of considerable benefit. Various parameters were used in order to identify the RMCS. The parameter comprised of Rock Quality Designation (RQD), Rock Mass Rating (RMR), Rock Structure Rating (RSR), Geological Strength Index (GSI), Slope Mass Rating (SMR), etc. In this paper, we present the results of the applicability of the Geological Strength Index (GSI) classification for the Trusmadi Formation in Sabah, Malaysia. The GSI classification system is based on the assumption that the rock mass contains a sufficient number of “randomly” oriented discontinuities such that it behaves as a homogeneous isotropic mass. In this study, the GSI relates the properties of the intact rock elements/blocks to those of the overall rock mass. It is based on an assessment of the lithology, structure and condition of discontinuity surfaces in the rock mass and is estimated from visual examination of the rock mass exposed in outcrops or surface excavations. A total of ten (10) locations were selected on the basis of exposures of the lithology and slope condition of the Trusmadi Formation. The Trusmadi Formation regionally experienced of two major structural orientations NW-SE and NE-SW. It consists mostly of dark grey shale with thin bedded sandstones, typical of a turbidite deposit. This unit has been subjected to low grade of metamorphism, producing slates, phyllites and meta-sediments and intense tectonic deformation producing disrupted or brecciated beds. Quartz vein are quite widespread within the joints on sandstone beds. The shale is dark grey when fresh but changes light grey to brownish when weathered. The results are classified as “Poor Rock” to “Fair Rock” in term of GSI. The poor categories (TR2 and TR7) represent slickensided, highly weathered surfaces with compact coatings or fillings or angular fragments. It is also characterized as blocky/ disturbed/seamy, which folded with angular blocks formed by many intersecting discontinuity sets. The fair categories can be divided into two (2) types; type 1 (TR1, TR6 and TR8) which represent as smooth, moderately weathered and have altered surfaces. It is also characterised as very blocky rock, which indicates interlocked, partially disturbed ass with multi-faceted angular blocks formed by 4 or more joint sets. Type 2 (TR3, TR4, TR5, TR9 and TR10) which represent as smooth, moderately weathered and have altered surfaces but characterized as blocky/disturbed/seamy, which folded with angular blocks formed by many intersecting discontinuity sets. It also has persistence of bedding planes or schistosity.
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Bonetto, Sabrina, Gessica Umili, Anna Maria Ferrero, Rodolfo Carosi, Matteo Simonetti, Alessandro Biasi, Maria Rita Migliazza, and Stefano Bianchini. "Geostructural and Geomechanical Study of the Piastrone Quarry (Seravezza, Italy) Supported by Photogrammetry to Assess Failure Mode." Geosciences 10, no. 2 (February 8, 2020): 64. http://dx.doi.org/10.3390/geosciences10020064.
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The use of non-contact-techniques for rock mass characterization has been growing significantly over the last decade. However, their application to stability assessment of ornamental stone has not yet received much attention from researchers. This study utilizes rock mass data both in terms of slope orientations and degree of fracturing obtained from a point cloud, a set of three-dimensional (3D) points representing a rock mass surface, to (1) investigate the influence of geostructures at different scales and (2) assess quarry stability by determining areas susceptible to different failure types. Multi-resolution point clouds are obtained through several photogrammetric survey techniques to identify important structural elements of the site. By integrating orientation data of discontinuity planes, obtained with a traditional survey, and of traces, outlined on point clouds, several joint sets were identified. Kinematic tests revealed various potential failure modes of the rock slope. Moreover, an analysis of the influence of the discontinuity strength determined by the presence of rock bridges was carried out. The study revealed that the strength of the quarry face is governed by the presence of rock bridges that act to improve the stability condition of the rock fronts.
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Taboni, Battista, Iuri Dino Tagliaferri, and Gessica Umili. "A Tool for Performing Automatic Kinematic Analysis on Rock Outcrops." Geosciences 12, no. 12 (November 24, 2022): 435. http://dx.doi.org/10.3390/geosciences12120435.
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The assessment of rock outcrops’ predisposition to the main possible kinematisms represents the preliminary step of stability analysis: Markland’s tests for sliding and toppling constitute a milestone due to the ease of use and interpretation of results. Orientation and friction angles of the main discontinuity sets and orientation of rock faces are required as input to perform the test on a stereonet graphically. However, for natural outcrops, the orientation of rock faces could vary significantly, and the test should be performed assuming all the representative ones. To speed up this process, the authors set up an automatic procedure based on the GIS environment working principles and developed it in Matlab language. Main discontinuity sets orientation and relative friction angles, along with slope and aspect data representing the rockface orientation of the considered outcrop, are the input data. The slope and aspect data are in GeoTIFF format, the most common format for georeferenced raster files employed in a GIS environment. The Matlab code performs Markland’s tests for planar and wedge sliding and flexural toppling, considering all the possible sets or intersections of sets, and provides the output with the same extent and georeferencing of the input data. The outputs are a series of GeoTIFF raster files describing the result for each kinematism separately and globally, which can be imported directly into GIS. The global results can also be used to map source areas for 3D rockfall numerical simulations. The code was validated through a case study by comparing its results with those obtained by performing the conventional tests singularly on a number of significant rock faces. The results obtained in the case study show that the algorithm produces reliable results consistent with those provided by traditional methods.
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Bhattarai, Sunita, and Naresh Kazi Tamrakar. "Field-based assessment of rock discontinuity and geological attributes of rock mass for stones for various engineering applications." Journal of Nepal Geological Society 55, no. 1 (June 4, 2018): 123–32. http://dx.doi.org/10.3126/jngs.v55i1.22801.
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Because of the occurrence of various rock types within the short span of areas, the Malekhu Khola area is one of the most promising areas where scope of stones is high. This paper presents recognition of the most promising rock types in terms of their geology and discontinuity for evaluating suitability for building stones. The research focuses on the assessment of nine different rock types allocated along the Malekhu Khola, central Nepal. Geological parameters, rock mass characterization and discontinuity analysis were carried out in each of allocated sites. During field study, rock masses were categorised based on different geological parameters, and on number of joint set, tentative block shape, size and volume. Field-based data were tabulated, analysed, and finally identified for the block size and geometry, and rock mass quality for stones. The number of major joint set ranges from one to four with random joint sets. The study shows that the outcrop condition of rock is faintly to slightly weathered and strongly indurated. The study shows that the rock types depending on the Rock Mass Rating (RMR) system vary from poor to very good. The block types that could be extracted are flat, long and compact. The probable end uses of these rock types could be armourstone, interior and exterior paving, cladding and foundation.
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Abd Rahim, Ismail, and Mohamad Saiful Nizam Mohamad. "TUNNEL SUPPORT BY ROCK QUALITY INDEX (Q) SYSTEM FOR ULTRABASIC ROCK: A CASE STUDY IN TELUPID, SABAH, MALAYSIA." Malaysian Journal of Geosciences 4, no. 1 (February 28, 2020): 22–25. http://dx.doi.org/10.26480/mjg.01.2020.22.25.
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The study area is underlain by the ultrabasic rock of partly Sabah Ophiolite Complex of Cretaceous ages. The objectives of this study are to determine the Q-value and to estimate the permanent support measures for 20m span, 10m high and eastern direction of the proposed tunnel in the study area. Engineering geological mapping (lithological and surface mapping and discontinuity survey), laboratory study (petrographical study) and testing (Uniaxial Compressive Strength testing) and data analysis (stereographic plots, Q system parameters evaluation and support estimation) was used in this study. The results show that the rock mass is classified as lherzolite, strong, excellent quality, more than four joint sets, slightly altered discontinuity wall, dry excavation and favourable stress condition. The equivalence dimension (De) are 15.4 for the permanent roof. The Q-value for permanent roof and wall of the proposed tunnel are 1.4 (Class D or poor and type 5) and 3.5 (Class D or poor and type 3), respectively. The permanent and temporary supports for the roof and wall are systematic bolting, 700J energy absorption of fiber reinforce sprayed concrete, 9-12 and 5- 6 cm thick fiber reinforce shotcrete, respectively.
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Aydan, O., Y. Shimizu, and Y. Ichikawa. "Effective failure modes and stability of slopes in rock mass with two discontinuity sets." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 27, no. 2 (April 1990): A112. http://dx.doi.org/10.1016/0148-9062(90)95253-w.
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Cui, Xuejie, and E.-chuan Yan. "A clustering algorithm based on differential evolution for the identification of rock discontinuity sets." International Journal of Rock Mechanics and Mining Sciences 126 (February 2020): 104181. http://dx.doi.org/10.1016/j.ijrmms.2019.104181.
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Umili, Gessica, Sabrina Maria Rita Bonetto, Pietro Mosca, Federico Vagnon, and Anna Maria Ferrero. "In Situ Block Size Distribution Aimed at the Choice of the Design Block for Rockfall Barriers Design: A Case Study along Gardesana Road." Geosciences 10, no. 6 (June 7, 2020): 223. http://dx.doi.org/10.3390/geosciences10060223.
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When studying rockfall phenomena, a single value of the block volume is not sufficient to take into account the natural variability of the geometrical features (orientation, spacing, persistence) of the discontinuity sets. Different approaches for obtaining cumulative distributions of potentially detachable block volumes are compared. A highly fractured rock mass outcropping along the western Lake Garda (Italy), consisting of prevailing limestone and interbedded marls, is studied in detail from geological and geostructural points of view. Then, a representative rock face has been selected and analyzed with traditional and non-contact survey methods to identify the main discontinuity sets and to collect spacing samples. Based on these data, in situ block size distributions for different combinations of sets are built following statistically-based approaches, without the use of a Discrete Fracture Network (DFN) generator. The validation of the obtained distributions is attempted based on the detached block surveyed at the foot of the slope. However, in this particular case study, the detached blocks cover only a minimal volume range compared to both theoretical values and visible rockfall scars. The fallen rock blocks have a marginal role in design block determination, since their volume depends on geological discontinuities (bedding and fractures) and could be affected by other processes after the detachment (e.g., fragmentation). The procedure here described should be standard practice in the study of rockfall events, and it should be uniform in European standards such as Eurocodes. Future developments should involve the scientific community for setting the percentiles of the probability distribution to be considered for block design definition.
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Udovič, Dalibor, Branko Kordić, and Željko Arbanas. "Geotechnical Study of Raspadalica Cliff Rockfall, Croatia." Applied Sciences 12, no. 13 (June 28, 2022): 6532. http://dx.doi.org/10.3390/app12136532.
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The Raspadalica Cliff is an almost vertical 100 m high limestone cliff with a railway line at its foot and is known for numerous rockfall occurrences in the past. This article presents the results of the geotechnical study of the cliff based on a traditional geological and geotechnical field survey and remote sensing analysis. Both the traditional geological and geotechnical field survey and remote sensing surveys and analyses enabled the establishment of the structural model of the Raspadalica Cliff and the determination of the discontinuity sets and discontinuity features, such as orientation, spacing, persistence, roughness, discontinuity wall strength, aperture, degree of weathering of discontinuity wall, seepage conditions, and the presence and hardness of discontinuity filling. Kinematic analyses were performed on five cliff zones with slightly different structural features, indicating a relatively low probability of typical failures in the cliff rock mass that precede the rockfall occurrences. Although rockfall phenomena from the cliff face are relatively frequent, the kinematic analyses did not indicate a high probability of their occurrence. The aim of this manuscript is to make scientists and practitioners aware that investigation of rock mass cliffs and possible rockfall failures must not be based on usual methods without critical review of the obtained results and consequences. The combined use of traditional geological and geotechnical methods and more commonly used advanced remote sensing methods leads to better modelling, while the analysis of more associated failure modes can explain the triggering of rockfall.
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Paudel, Prem Nath, and Naresh Kazi Tamrakar. "Geology and rockmass condition of Dhulikhel-Panchkhal area, Kavre District, Central Nepal Lesser Himalaya." Bulletin of the Department of Geology 15 (January 21, 2013): 1–14. http://dx.doi.org/10.3126/bdg.v15i0.7412.
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A geological mapping was carried out and the rock mass characteristics of the Lesser Himalayan rocks distributed in the Dhulikhel-Panchkhal area (Kavre Distric) were studied along with their physical and mechanical properties. The lithological units distributed in the study area belong to the Benighat Slate of the Upper Nawakot Group and the Bhimphedi Group as separated by the Chak-Rosi Thrust. The lithological units strike NW-SE and dip southwards forming the eastern closure of part of the northern limb of the Mahabharat synclinorium. The area comprises mainly micaceous quartzite, psammitic schist, metasandstone and metasiltstone. Micaceous quartzite is a rock type of the Kalitar Formation, Chisapani quartzite and the Markhu Formation. The Markhu quartzite is slightly calcareous. Psammitic schist is a rock type of the Kulekhani Formation and the Markhu Formation. Metasandstone and metasiltstone are the rock types of the Tistung Formation. The rock masses consist mainly of three to four major joint sets including the joint parallel to foliation. The discontinuity characteristics indicate that the rocks are blocky in nature, and nearly smooth to rough surface with soft filling aperture. The rock mass is nearly fresh, indurated and stiff. The slopes are influenced by stable and unstable wedges, plane and toppling failures. The rock masses are classified into fair to good rock classes according to rock mass rating system. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7412 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 1–14
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Md Shah, Nazlin An’Nisa, Abdul Ghani Rafek, Ailie Sofyiana Serasa, Wan Salmi Wan Harun, Muslim Abdurrahman, Lee Khai Ern, Nguyen Xuan Huy, et al. "Engineering Geological Assessment at Grandview Heights, Paya Terubong, Pulau Pinang, Malaysia." IOP Conference Series: Earth and Environmental Science 1103, no. 1 (November 1, 2022): 012035. http://dx.doi.org/10.1088/1755-1315/1103/1/012035.
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Grandview Heights, Paya Terubong is an old apartment building situated on a coarse-grained biotite granitic bedrock hillside. Paya Terubong is a landslide prone area where various landslides have been reported since 1998. The granitic hill has been disturbed during construction of the apartment. Due to the possibility of future landslides, an engineering geological study was conducted to assess the stability of this rock hill beneath this apartment. The scopes of study included discontinuity surveys, geomechanical characterization of the rock mass and slope stability analysis. Based on the results of discontinuity surveys, four major joints sets-were identified and labelled as J1 (195°/62°), J2 (248°/65°), J3 (304°/63°) and J4 (230°/39°). One (1) potential planar failure J2 (248°/65°) and one (1) potential wedge failure J1-J2 intersection (213°/60°) were identified based on kinematic analysis. Dry rock density was from 2.56 g/cm3 to 2.61g/cm3. The water content was from 0.14 % to 0.15% with low porosity values from 0.50% to 0.54%. The point load strength index, Is(50) was 6.63 MPa. The Slope Mass Rating (SMR) for was 64 to 79 and classified as class II with the probability of failure of 0.2.
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Aydan, �., Y. Shimizu, and Y. Ichikawa. "The effective failure modes and stability of slopes in rock mass with two discontinuity sets." Rock Mechanics and Rock Engineering 22, no. 3 (July 1989): 163–88. http://dx.doi.org/10.1007/bf01470985.
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Li, Yanyan, Qing Wang, Jianping Chen, Liming Xu, and Shengyuan Song. "K-means Algorithm Based on Particle Swarm Optimization for the Identification of Rock Discontinuity Sets." Rock Mechanics and Rock Engineering 48, no. 1 (March 22, 2014): 375–85. http://dx.doi.org/10.1007/s00603-014-0569-x.
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Riquelme, A., M. Cano, R. Tomás, and A. Abellán. "Identification of Rock Slope Discontinuity Sets from Laser Scanner and Photogrammetric Point Clouds: A Comparative Analysis." Procedia Engineering 191 (2017): 838–45. http://dx.doi.org/10.1016/j.proeng.2017.05.251.
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Azzuhry, Yahdi. "STABILITY ANALYSIS AND FAILURE MECHANISMS OF OPEN PIT ROCK SLOPE." Journal of the Civil Engineering Forum 2, no. 3 (August 16, 2017): 255. http://dx.doi.org/10.22146/jcef.26589.
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Rock mass in nature tend to be unideal, for it is heterogeneous, anisotropic and has discontinuity. The discontinuity makes anisotropic strength and stress in the rock mass, and also controls the changing of the elastic properties of rock mass. This condition results to disruptions in the rock mass strength balance, and finally drives the slopes to collapse. This study aims to determine the slope failure mechanisms in the area of case study, as well as its variations based on the Rock Mass Rating (RMR), Geological Strength Index (GSI), Slope Mass Rating (SMR), kinematic analysis, numerical analysis and monitoring approach slope movement in a coal mine slope applications. The site investigations were implemented to obtain information about slope collapse. Prior to the collapse, the slope inclination was 38° with of 94 meters height, strike slope of N 245 E and direction of slope surface of 335°. After the collapse, the slope was became 25º; and after the collapse materials were cleared, it was 35º. The discontinuity mapping obtained 5 sets of discontinuities, and the data were developed to obtain the value of RMR. The result of piezometer measurements was that at occurrence of collapse, slope elevation was 44.40m. Displacement value from monitoring SSMR showed that when the slope was collapsing in two stages, the first stage value was 70.61cm (a more critical condition, the value was rounded down to 70cm to the implementation in modelling) and the second stage value was at 124.25cm. The value of RMR89 in this study was greater than the value of GSI and SMR. As for the average value, it was obtained 34.67 for RMR89 value and 29.67 for GSI value, these rocks then can be classified into Poor Rock class number IV. The result of kinematic analysis found that sliding planar failure at dips 36°, and wedge failure at dips 36°, 35° and 34°. Acquisition SMR value obtained at 25, 27, 28 and 29. The SMR values classified the rock mass quality into class number IV, the description of the rock mass was relatively poor, the slope stability was low or unstable and the collapse manifold was planar or wedge failure. The result from the analysis of the model with its criteria obtained was that un-collapse conditions at angle 29°. It is recommended to use 29° angle to repair the slopes, and also recommended for overall high wall slope angle. Type of collapse that occurred on the slope failure mechanisms in all of the analysis that has been done, it is known that the mechanisms involved are complex types (combine of wedge failure, planar failure, and step-path failure) or classified into large scale rock slope failure surface.
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Abdul Rahim, Afiq Farhan, Abdul Ghani Rafek, Ailie Sofyiana Serasa, Rini Asnida Abdullah, Afikah Rahim, Wan Salmi Wan Harun, Swee Yeok Foong, et al. "Application of a Comprehensive Rock Slope Stability Assessment Approach for Selected Malaysian Granitic Rock Slopes." Sains Malaysiana 51, no. 2 (February 28, 2022): 421–36. http://dx.doi.org/10.17576/jsm-2022-5102-08.
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In Malaysia, rock slope stability analysis has been largely confined to kinematic analysis with rock mass rating systems as assessment tools for stability analysis. While this method addresses the fundamental issues of rock slope stability including identifying potential failure modes, an information gap still exists between geologists and engineers in designing proper mitigation measures for rock slopes. This paper aims to address this issue by incorporating several methodologies, including kinematic analysis, slope mass rating and the Barton-Bandis criterion for the limit equilibrium method. Four rock slopes with potential instabilities namely KSA, KSB, LHA, and LHB were studied. KSA and KSB were located near Kajang, Selangor while LHA and LHB were located near Rawang, Selangor. Each slope exhibits multiple potential failures, with attention given on sliding-type failures in planar or wedge form. A slope mass rating value was assigned to each potential failure based on rock mass ratingbasic and the slope mass rating based on readjustments for discontinuity orientation and excavation method. Factor of safety from limit equilibrium method show potentially unstable blocks and failed blocks (Factor of Safety <1.00) with confirmation on site. Water filling of discontinuity apertures plays an important role in destabilizing rock blocks, especially in wet conditions experienced in Malaysia’s tropical climate. Several geometries are identified as potentially unstable due to low slope mass rating (Class V) and factor of safety of <1.2, such as planar J5 and wedge J2*J5 at KSA, wedge forming with sets J3, J4 and fault plane at KSB, planar J2 at LHA, and wedge J3*J4 at LHB. Stabilization structures such as rock bolts can be better designed with the determined factor of safety values coupled with relevant geological and geotechnical inputs. In this comprehensive rock slope stability assessment approach, limit equilibrium method serves as a useful method in analyzing rock slope stability to complement kinematic analysis and stability ratings often used in Malaysia.
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Jaboyedoff, M., F. Baillifard, F. Philippossian, and J. D. Rouiller. "Assessing fracture occurrence using "weighted fracturing density": a step towards estimating rock instability hazard." Natural Hazards and Earth System Sciences 4, no. 1 (March 9, 2004): 83–93. http://dx.doi.org/10.5194/nhess-4-83-2004.
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Abstract. Based on the assumption that major class of rock instabilities are created by discontinuities, a method is proposed to estimate the fracture density by means of a digital elevation model (DEM). By using the mean orientation, the mean spacing and the mean trace length of discontinuity sets potentially involved in slope instabilities and a DEM, it is possible to calculate the mean number of discontinuities of a given set per cell of the DEM. This would allow for an estimation of the probability of the presence of at least one discontinuity in a given area or simply in a topographic cell of the DEM. This analysis highlights sites potentially affected by rockslides within a region. Depending on the available data, the mean number can be calculated either by area, or along a line parallel to the mean apparent spacing. The effective use of the probability of occurrence is dependent on the size of the discontinuities because short and closely spaced discontinuities will have a 100% probability of occurrence in each favorable location. The a posteriori prediction of a recent rockslide is discussed as an example.
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Mammoliti, Elisa, Francesco Di Stefano, Davide Fronzi, Adriano Mancini, Eva Savina Malinverni, and Alberto Tazioli. "A Machine Learning Approach to Extract Rock Mass Discontinuity Orientation and Spacing, from Laser Scanner Point Clouds." Remote Sensing 14, no. 10 (May 13, 2022): 2365. http://dx.doi.org/10.3390/rs14102365.
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This study wants to give a contribution to the semi-automatic evaluation of rock mass discontinuities, orientation and spacing, as important parameters used in Engineering. In complex and inaccessible study areas, a traditional geological survey is hard to conduct, therefore, remote sensing techniques have proven to be a very useful tool for discontinuity analysis. However, critical expert judgment is necessary to make reliable analyses. For this reason, the open-source Python tool named DCS (Discontinuities Classification and Spacing) was developed to manage point cloud data. The tool is written in Python and is based on semi-supervised clustering. By this approach the users can: (a) estimate the number of discontinuity sets (here referred to as “clusters”) using the Error Sum of Squares (SSE) method and the K-means algorithm; (b) evaluate step by step the quality of the classification visualizing the stereonet and the scatterplot of dip vs. dip direction from the clustering; (c) supervise the clustering procedure through a manual initialization of centroids; (d) calculate the normal spacing. In contrast to other algorithms available in the literature, the DCS method does not require complex parameters as inputs for the classification and permits the users to supervise the procedure at each step. The DCS approach was tested on the steep coastal cliff of Ancona town (Italy), called the Cardeto–Passetto cliff, which is characterized by a complex fracturing and is largely affected by rockfall phenomena. The results of discontinuity orientation were validated with the field survey and compared with the ones of the FACETS plug-in of CloudCompare. In addition, the algorithm was tested and validated on regular surfaces of an anthropic wall located at the bottom of the cliff. Eventually, a kinematic analysis of rock slope stability was performed, discussing the advantages and limitations of the methods considered and making fundamental considerations on their use.
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Pagano, Marco, Biagio Palma, Anna Ruocco, and Mario Parise. "Discontinuity Characterization of Rock Masses through Terrestrial Laser Scanner and Unmanned Aerial Vehicle Techniques Aimed at Slope Stability Assessment." Applied Sciences 10, no. 8 (April 24, 2020): 2960. http://dx.doi.org/10.3390/app10082960.
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Stabilization projects of rock masses cannot be performed without a proper geomechanical characterization. The classical approaches, due to logistic issues, typically are not able to cover extensively the areas under study. Geo-structural analysis on point cloud from terrestrial laser scanning and photogrammetry from unmanned aerial vehicles are valid tools for analysis of discontinuity systems. Such methodologies provide reliable data even in complex environmental settings (active cliffs) or at inaccessible sites (excavation fronts in tunnels), offering advantages in terms of both safety of the operators and economic and time issues. We present the implementation of these techniques at a tuff cliff over the Santa Caterina beach (Campania) and at the main entrance of Castellana Caves (Apulia). In the first case study, we also perform an integration of the two techniques. Both sites are of significant tourist and economic value, and present instability conditions common to wide areas of southern Italy: namely, retrogressive evolution of active cliffs along the coast, and instability at the rims of natural and/or artificial sinkholes. The results show the reliability of the data obtained through semi-automatic methods to extract the discontinuity sets from the point clouds, and their agreement with data collected in the field through classical approaches. Advantages and drawbacks of the techniques are illustrated and discussed.
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Song, Shengyuan, Qing Wang, Jianping Chen, Yanyan Li, Wen Zhang, and Yunkai Ruan. "Fuzzy C-means clustering analysis based on quantum particle swarm optimization algorithm for the grouping of rock discontinuity sets." KSCE Journal of Civil Engineering 21, no. 4 (November 4, 2016): 1115–22. http://dx.doi.org/10.1007/s12205-016-1223-9.
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Cui, Xuejie, and E.-chuan Yan. "Fuzzy C-Means Cluster Analysis Based on Variable Length String Genetic Algorithm for the Grouping of Rock Discontinuity Sets." KSCE Journal of Civil Engineering 24, no. 11 (September 4, 2020): 3237–46. http://dx.doi.org/10.1007/s12205-020-2188-2.
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Loiotine, Lidia, Charlotte Wolff, Emmanuel Wyser, Gioacchino Francesco Andriani, Marc-Henri Derron, Michel Jaboyedoff, and Mario Parise. "QDC-2D: A Semi-Automatic Tool for 2D Analysis of Discontinuities for Rock Mass Characterization." Remote Sensing 13, no. 24 (December 14, 2021): 5086. http://dx.doi.org/10.3390/rs13245086.
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Quantitative characterization of discontinuities is fundamental to define the mechanical behavior of discontinuous rock masses. Several techniques for the semi-automatic and automatic extraction of discontinuities and their properties from raw or processed point clouds have been introduced in the literature to overcome the limits of conventional field surveys and improve data accuracy. However, most of these techniques do not allow characterizing flat or subvertical outcrops because planar surfaces are difficult to detect within point clouds in these circumstances, with the drawback of undersampling the data and providing inappropriate results. In this case, 2D analysis on the fracture traces are more appropriate. Nevertheless, to our knowledge, few methods to perform quantitative analyses on discontinuities from orthorectified photos are publicly available and do not provide a complete characterization. We implemented scanline and window sampling methods in a digital environment to characterize rock masses affected by discontinuities perpendicular to the bedding from trace maps, thus exploiting the potentiality of remote sensing techniques for subvertical and low-relief outcrops. The routine, named QDC-2D (Quantitative Discontinuity Characterization, 2D) was compiled in MATLAB by testing a synthetic dataset and a real case study, from which a high-resolution orthophoto was obtained by means of Structure from Motion technique. Starting from a trace map, the routine semi-automatically classifies the discontinuity sets and calculates their mean spacing, frequency, trace length, and persistence. The fracture network is characterized by means of trace length, intensity, and density estimators. The block volume and shape are also estimated by adding information on the third dimension. The results of the 2D analysis agree with the input used to produce the synthetic dataset and with the data collected in the field by means of conventional geostructural and geomechanical techniques, ensuring the procedure’s reliability. The outcomes of the analysis were implemented in a Discrete Fracture Network model to evaluate their applicability for geomechanical modeling.
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Aksoy, H., and M. Ercanoglu. "Determination of the rockfall source in an urban settlement area by using a rule-based fuzzy evaluation." Natural Hazards and Earth System Sciences 6, no. 6 (October 27, 2006): 941–54. http://dx.doi.org/10.5194/nhess-6-941-2006.
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Abstract. The evaluation of the rockfall initiation mechanism and the simulation of the runout behavior is an important issue in the prevention and remedial measures for potential rockfall hazards in highway protection, in forest preservation, and especially in urban settlement areas. In most of the studies in the literature, the extent of the rockfall hazard was determined by various techniques basing on the selection of a rockfall source, generally defined as zones of rock bodies having slope angles higher than a certain value, proposed by general practice. In the present study, it was aimed to carry out a rule-based fuzzy analysis on the discontinuity data of andesites in the city of Ankara, Turkey, in order to bring a different and rather systematic approach to determine the source areas for rockfall hazard in an urban settlement, based on the discontinuity and natural slope features. First, to obtain rock source areas (RSAs), data obtained from the field studies were combined with a rule-based fuzzy evaluation, incorporating the altitude difference, the number of discontinuities, the number of wedges and the number of potential slides as the parameters of the fuzzy sets. After processing the outputs of the rule-based fuzzy system and producing the linguistic definitions, it could be possible to obtain potential RSAs. According to the RSA maps, 1.7% of the study area was found to have "high RSA", and 5.8% of the study area was assigned as "medium RSA". Then, potential rockfall hazard map was prepared. At the final stage, based upon the high and medium RSAs, 3.6% of the study area showed "high rockfall potential", while areal distribution of "medium rockfall potential" was found as 7.9%. Both RSA and potential rockfall hazard map were in accordance with the observations performed in the field.
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Luzon, Paul Kenneth, Kristina Montalbo, Jam Galang, Jasmine May Sabado, Carmille Marie Escape, Raquel Felix, and Alfredo Mahar Francisco Lagmay. "Hazard mapping related to structurally controlled landslides in Southern Leyte, Philippines." Natural Hazards and Earth System Sciences 16, no. 3 (April 1, 2016): 875–83. http://dx.doi.org/10.5194/nhess-16-875-2016.
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Abstract. The 2006 Guinsaugon landslide in Saint Bernard, Southern Leyte, is one of the largest known landslides in the Philippines in recent history. It consists of a 15–20 million m3 rockslide-debris avalanche from an approximately 675 m high mountain weakened by continuous movement of the Philippine Fault. The catastrophic Guinsaugon landslide killed 1221 people and displaced 19 000 residents over its 4.5 km path. To investigate the present-day morphology of the scar and potential failure that may occur, analysis of a 5 m resolution InSAR-derived digital elevation model was conducted using Coltop3D and Matterocking software, leading to the generation of a landslide hazard map for the province of Southern Leyte in central Philippines. The dip and dip direction of discontinuity sets that contribute to gravitational failure in mountainous areas of the province were identified and measured using a lower Schmidt–Lambert color scheme. After measurement of the morpho-structural orientations, potential sites of failure were analyzed. Conefall was then utilized to compute the extent of rock mass runout. Results of the analysis show instability in the scarp area of the 2006 Guinsaugon landslide and in adjacent slopes because of the presence of steep discontinuities that range from 45 to 60°. Apart from the 2006 Guinsaugon landslide site, runout models simulated farther rock mass extent in its adjacent slopes, revealing a high potential for fatal landslides to happen in the municipality of Saint Bernard. Concerned agencies may use maps produced in the same manner as this study to identify possible sites where structurally controlled landslides can occur. In a country like the Philippines, where fractures and faults are common, this type of simulated hazard maps would be useful for disaster prevention and facilitate disaster risk reduction efforts for landslide-susceptible areas.
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Luzon, P. K., K. P. Montalbo, J. A. M. Galang, J. M. Sabado, C. M. Escape, R. P. Felix, and A. M. F. Lagmay. "Structurally controlled hazard mapping of Southern Leyte, Philippines." Natural Hazards and Earth System Sciences Discussions 3, no. 10 (October 1, 2015): 5891–921. http://dx.doi.org/10.5194/nhessd-3-5891-2015.
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Abstract. The 2006 Guinsaugon landslide in St. Bernard, Southern Leyte is one of the largest known landslides in the Philippines in recent history. It consists of a 15–20 million m3 rockslide-debris avalanche from an approximately 675 m high mountain weakened by continuous movement of the Philippine fault. The catastrophic Guinsaugon landslide killed 1221 people and displaced 19 000 residents over its 4.5 km path. To investigate the present day morphology of the scar and potential failure that may occur, analysis of a 5 m resolution IfSAR-derived Digital Elevation Model was conducted using Coltop3D and Matterocking software, leading to the generation of a landslide hazard map for the province of Southern Leyte in Central Philippines. The dip and dip-direction of discontinuity sets that contribute to gravitational failure in mountainous areas of the province were identified and measured using a lower Schmidt-Lambert color scheme. After measurement of the morpho-structural orientations, potential sites of failure were analyzed. Conefall was then utilized to compute the extent of rock mass runout. Results of the analysis show instability in the scarp area of the 2006 Guinsaugon landslide and in adjacent slopes because of the presence of steep discontinuities that range from 45–60°. Apart from the 2006 Guinsaugon landslide site, runout models simulated farther rock mass extent in its adjacent slopes, revealing a high potential for fatal landslides to happen in the municipality of St. Bernard. Concerned agencies may use maps produced in the same manner as this study to identify possible sites where structurally-controlled landslides can occur. In a country like the Philippines, where fractures and faults are common, this type of simulated hazard maps would be useful for disaster prevention and facilitate disaster risk reduction efforts for landslide-susceptible areas.
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Eberth, David A., and Anthony P. Hamblin. "Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River wedge) of southern Alberta, Saskatchewan, and northern Montana." Canadian Journal of Earth Sciences 30, no. 1 (January 1, 1993): 174–200. http://dx.doi.org/10.1139/e93-016.
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The lithostratigraphic interval between the Taber and Lethbridge coal zones in the upper portion of the nonmarine Judith River Group of southeastern Alberta is divisible into two lithostratigraphic units separated by a regionally extensive and diachronous discontinuity. The lower unit, referred to here as the Oldman Formation, is characterized by very fine grained to fine-grained sandstones that contain fewer than 2% volcanic rock fragments; sandstone bodies with numerous sets of horizontally stratified sandstone, showing little or no evidence of lateral accretion; siliceous paleosols (ganisters); and a relatively high gamma-ray signal in the upper half of the formation. The Oldman Formation comprises deposits of a low-sinuosity, perhaps ephemeral fluvial system that originated in the southern Cordillera of Canada and northern Montana and flowed northeastward, perpendicular to the axis of the Alberta Basin.The upper unit is assigned to a new formation, the Dinosaur Park Formation, and is characterized by fine- to medium-grained sandstones with up to 10% volcanic rock fragments; sandstone bodies that exhibit lateral-accretion surfaces in the form of inclined heterolithic stratification; numerous articulated dinosaurs and dinosaur bone beds; and a relatively low gamma-ray signal in the lower half of the formation. The Dinosaur Park Formation comprises deposits of a high-sinuosity, fluvial-to-estuarine system that originated in the north and central Cordillera and flowed southeastward, subparallel to the axis of the Alberta Basin.40Ar/39Ar and K–Ar dating of Judith River Group bentonites shows that the contact between the Oldman and Dinosaur Park formations becomes younger toward the south and southeast. These data also demonstrate that the Dinosaur Park Formation clastics migrated southeastward at a rate of approximately 130–140 km/Ma, gradually overstepping the Oldman Formation elastics.The widely recognized north-to-south increase in intensity of overthrust loading along the western margin of the Alberta Basin during the Late Cretaceous is thought to be responsible for (i) differences in accommodation space for the proximal portions of the Oldman and Dinosaur Park formations, and (ii) the establishment of a southerly tilt in the Alberta Basin leading to the southeastward migration of the Dinosaur Park Formation elastics. In the northern portion of the basin, relatively lower rates of subsidence, combined with periods of isostatic rebound in the foredeep, resulted in the southeastward migration of Dinosaur Park Formation elastics as sediment input exceeded accommodation space. In the southern portion of the basin, relatively higher rates of subsidence and little isostatic rebound acted to trap coarse-grained Oldman Formation elastics in the foredeep and may have led to periods of sediment starvation in more distal portions of the basin. An inferred lower depositional slope associated with the Dinosaur Park Formation (relative to the Oldman Formation) is thought to have resulted from gradual loading of the basin as Dinosaur Park Formation elastics migrated southeastward or some form of tectonically induced subsidence.
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Ghosh, Abhinandan. "Understanding basement fracture architecture in Padra Field, South Cambay Basin, India, through full-azimuth imaging." Leading Edge 38, no. 4 (April 2019): 262–67. http://dx.doi.org/10.1190/tle38040262.1.
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Detection and characterization of fractures in reservoirs is of great importance for maximizing hydrocarbon productivity and recovery efficiency. Fractures play an important role in the producibility of unconventional reservoirs such as basement reservoirs. Basement reservoirs are typically found within metamorphic and igneous rock underlying a sedimentary basin, where faulting and tectonic uplift has led to creation of a fracture network. For fracture characterization, integration of information from seismic and nonseismic data such as cores and/or formation microimaging (FMI) logs is essential. Various seismic attributes such as coherency and curvature that are derived from reflection seismic data have been used for more than a decade to detect faults and fractures. In advanced seismic fracture detection technology, automatic fault extraction (AFE) from diffraction seismic data (discontinuity volume) more effectively detects finer scale features in seismic data. We demonstrate the utility of this methodology with an application to seismic data from the Padra Field, South Cambay Basin, India, where the basaltic Deccan Trap forms the basement, and hydrocarbons are produced from basement fractures. Diffraction imaging was applied during processing of the full-azimuth 3D-3C seismic data that cover this field. Using wavefield decomposition in the subsurface local angle domain, separate reflection (specular) and diffraction data volumes were produced. The high-resolution specular stack data imaged a prominent reflector well below the trap top, which is not visible in conventional seismic reflection data. Diffraction stack data also provided higher resolution fault definition and enhanced imaging of spatially consistent geological discontinuities. Subsequent application of the AFE technique to diffraction-imaged data yielded sharp and crisp definition of faults and fractures. We also performed velocity variation with azimuth analysis of 3D angle-azimuth reflection gathers to generate a fracture orientation map. Both sets of results were validated by fractures detected in FMI logs from wells in the field.
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Peters, Shanan E. "Macrostratigraphy and Its Promise for Paleobiology." Paleontological Society Papers 14 (October 2008): 205–31. http://dx.doi.org/10.1017/s1089332600001698.
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Macrostratigraphy is the study and statistical analysis of sediment packages that formed continuously at a specified scale of temporal resolution and that are bound by gaps recognizable at that same scale. The temporal ranges of gap-bound packages, compiled separately for different geographic locations, permit area-weighted, survivorship-based measures of rock quantity and spatio-temporal environmental continuity to be measured. Analytical basin fill models suggest that the parameters controlling sedimentation and sequence stratigraphic architecture, such as base level and sediment supply, can be detected quantitatively by macrostratigraphy.Macrostratigraphic analysis of the marine sedimentary rock record in the United States at a temporal resolution of ~106 years reproduces most of the well-known Sloss sequences, but it also identifies two prominent megasequences, the Paleozoic and Modern megasequences, which are separated by a Permian-Triassic discontinuity and Phanerozoic minimum in rock quantity. Many short- and long-term features of the macroevolutionary history of marine animals are reproduced by macrostratigraphy, including 1) many patterns in genus richness, 2) patterns in rates of genus extinction and, to a lesser degree, rates of origination, and 3) patterns of extinction selectivity and the shifting relative richness of Sepkoski's Paleozoic and Modern evolutionary faunas. The extent to which macrostratigraphy reproduces the macroevolutionary history of marine animals transcends what is expected by geologically-controlled sampling biases. Instead, the processes which control the spatio-temporal dynamics of shelf sedimentation, including expansions and contractions of shallow epicontinental seas, have probably exerted a consistent influence on the macroevolutionary history of marine animals. Exploring the common cause hypothesis by putting fossils back into rocks and rocks into a new quantitative framework for physical environmental change holds considerable promise for paleobiology.
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Masihi, Mohsen, Peter R. King, and Peyman R. Nurafza. "Connectivity Prediction in Fractured Reservoirs With Variable Fracture Size: Analysis and Validation." SPE Journal 13, no. 01 (March 1, 2008): 88–98. http://dx.doi.org/10.2118/100229-pa.
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Summary Uncertainty in geometrical properties of fractures, when they are considered as the conductive paths for flow movement, affects all aspects of flow in fractured reservoirs. The connectivity of fractures, embedded in low-permeability zones, can control fluid movement and influence field performance. This can be analyzed using percolation theory. This approach uses the hypothesis that the permeability map can be split into either permeable (i.e., fracture) or impermeable (i.e., matrix) portions and assumes that the connectivity of fractures controls the flow. The analysis of the connectivity based on finite-size scaling assumes that fractures all have the same sizes. However, natural fracture networks involve a relatively wide range of fracture lengths, modeled by either scale-limited laws (e.g., log normal) or power laws. In this paper, we extend the applicability of the percolation approach to a system with a distribution of size. For scale-limited distributions, we use the hypothesis seen in the literature that the connectivity of fractures of variable size is identical to the connectivity of fractures of the same size whose length is given by an appropriate effective length. It is then necessary to define the percolation probability based on the excluded area arguments. In this research work, we also validate the applicability of this idea to fracture networks having a uniform, Gaussian, exponential, and log-normal length distribution. However, in the case of the power-law length distribution, we have found that the scaling parameters (e.g., correlation length exponent) have to be modified. The main contribution is to show how the critical exponents vary as a function of the power-law exponent. To validate the approach, we used outcrop data of mineralized fractures (vein sets) exposed on the southern margin of the Bristol Channel basin. We show that the predictions from the percolation approach are in good agreement with the results calculated from field data with the advantage that they can be obtained very quickly. As a result, they may be used for practical engineering purposes and may aid decision-making for real field problem. Introduction Many hydrocarbon reservoirs are naturally fractured. The conventional approach to investigate the impact of geological uncertainties on reservoir performance is to build a detailed reservoir model using available geophysical and geological data, upscale it, and then perform flow simulation. In fractured reservoirs, this can be done by using equivalent continuum models (i.e., dual porosity), discrete network models, or a combination of both [see Warren and Root (1963), Quenes and Hartley (2000), and Dershowitz et al. (2000)]. The nature of fluid flow in fractured reservoirs of low matrix permeability depends strongly on the spatial distribution of the conductive natural fractures. We use the term "fracture" to mean any discontinuity within a rock mass that developed as a response to stress. Fractures exist on various length scales from microns to kilometres. They appear as tensile (e.g., joints or veins) or shear (e.g., faults) and can act as hydraulic conductors or barriers to flow movement. Conductive fractures may be connected in a complicated manner to form a complex network. The connectivity of such networks is a crucial parameter in controlling flow movement, which in turn depends on the geometrical properties of the network such as fracture orientation, spacing, or length distribution.
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Tomás, R., A. Riquelme, M. Cano, J. L. Pastor, J. I. Pagán, J. L. Asensio, and M. Ruffo. "Evaluación de la estabilidad de taludes rocosos a partir de nubes de puntos 3D obtenidas con un vehículo aéreo no tripulado." Revista de Teledetección, no. 55 (June 23, 2020): 1. http://dx.doi.org/10.4995/raet.2020.13168.
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<p>In this work, a methodology proposed for the semiautomatic identification of discontinuities and the later kinematic and stability analyses is described through its application to a rocky railway line cutting. Image acquisition has been performed using a six-rotors unmanned aerial vehicle for their subsequent photogrammetric restitution by means of the digital technique Structure from Motion (SfM) by means of the software Agisoft Metashape that provides a 3D point cloud. From this 3D point cloud, four discontinuity sets (J<sub>1</sub>, J<sub>2</sub>, J<sub>3</sub> and J<sub>4</sub>) affecting the cutting have been identified using the open source software Discontinuity Set Extractor (DSE). Finally, kinematic and stability analyses of the potential block failures controlled by the discontinuities identified in the cutting. The results show three potential wedge and planar failures that have been qualitatively validated trough the geometric analysis of the 3D point cloud.<em></em></p>
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Riquelme, A., R. Tomás, M. Cano, J. L. Pastor, and L. Jordá-Bordehore. "Extraction of discontinuity sets of rocky slopes using iPhone-12 derived 3DPC and comparison to TLS and SfM datasets." IOP Conference Series: Earth and Environmental Science 833, no. 1 (August 1, 2021): 012056. http://dx.doi.org/10.1088/1755-1315/833/1/012056.
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Fergusson, C. L., and P. A. Cawood. "Structural history of the metamorphic sole of the Bay of Islands Complex, western Newfoundland." Canadian Journal of Earth Sciences 32, no. 5 (May 1, 1995): 533–44. http://dx.doi.org/10.1139/e95-045.
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Displacement of the Early Ordovician ophiolitic Bay of Islands Complex was accompanied by the development of a metamorphic sole in underlying accreted gabbro, mafic pillow lava, pelite, and psammite. The metamorphic sole contains up to 130 m of amphibolite, underlain by up to 80 m of mafic and pelitic–psammitic schist, which, in turn, overlies chlorite-bearing rocks that overlie mudstone-matrix mélange. A major foliation, locally mylonitic and (or) isoclinally folded, is pervasively developed in the greenschists and amphibolites. An extension lineation is widely developed and plunges north in amphibolite and trends east–west in greenschist, consistent with a changing direction of thrust transport from northerly to westerly as the mantle wedge cooled over time. Shear sense criteria in greenschist facies pelitic–psammitic schist indicate thrusting towards the west. In the southwestern Blow-Me-Down massif, two sets of folds postdate development of accretion-related S-L fabrics and resulted in a substantial widening of the metamorphic sole. Late disruption by foliation-parallel, low-angle extensional and steep faults have excised parts of the metamorphic sole, resulting in a marked discontinuity of units along strike. Extensional faults were induced by gravitational spreading as the Coulomb thrust wedge, containing the ophiolite, metamorphic sole, and underlying mélange unit, became supercritical. This was probably due to a combination of two factors: (1) development of a substantially weakened basal mélange layer and (2) lowering of the basal slope of the wedge as it was thrust over the Ordovician slope onto the shelf.
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Lowe, C., and G. Ranalli. "Density, temperature, and rheological models for the southeastern Canadian Cordillera: implications for its geodynamic evolution." Canadian Journal of Earth Sciences 30, no. 1 (January 1, 1993): 77–93. http://dx.doi.org/10.1139/e93-007.
Full textAbstract:
Two-dimensional density, temperature, and rheological models are constructed for a 350 km northeast-trending transect of the southeastern Canadian Cordillera. All models highlight several major physical differences between foreland and hinterland lithosphere. Significant features of the density model are the presence of an anomalously low-density (3.10 × 103 kg∙m−3) layer, with a maximum thickness of 12 km, beneath the Moho in the hinterland; the similar densities of the Monashee Terrane and the cratonic crust of the foreland; and an increase in crustal thickness beneath the Southern Rocky Mountain Trench. The temperature model shows steeper gradients and higher Moho temperatures beneath the hinterland than beneath the foreland. In the rheological model the hinterland is characterized by a thin, brittle, upper crust beneath which the entire lithosphere is hot, weak, and ductile. In contrast, the foreland is composed of a thick, brittle, upper crust, with an additional brittle zone in the upper mantle. The Moho is a large strength discontinuity beneath the foreland, and the total lithospheric strength there is an order of magnitude larger than in the hinterland. The models are constrained and supported by geological mapping and a number of independent geophysical data sets. Palinspastic cross sections, together with paleotemperature and paleopressure information, are used to generate a time series of one-dimensional paleorheological profiles at a number of times during deformation. This sequence of profiles indicates that the foreland and hinterland have been rheologically distinct since pre-Late Cretaceous times. The profiles are used to clarify the geodynamic evolution of the area and to explain why deformation remained thin skinned in the foreland whereas in the hinterland the entire lithosphere was deformed.
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Chian, Deping, François Marillier, Jeremy Hall, and Garry Quinlan. "An improved velocity model for the crust and upper mantle along the central mobile belt of the Newfoundland Appalachian orogen and its offshore extension." Canadian Journal of Earth Sciences 35, no. 11 (November 1, 1998): 1238–51. http://dx.doi.org/10.1139/e98-042.
Full textAbstract:
New modelling of wide-angle reflection-refraction data of the Canadian Lithoprobe East profile 91-1 along the central mobile belt of the Newfoundland Appalachian orogen reveals new features of the upper mantle, and establishes links in the crust and upper mantle between existing land and marine wide-angle data sets by combining onshore-offshore recordings. The revised model provides detailed velocity structure in the 30-34 km thick crust and the top 30 km of upper mantle. The lower crust is characterized by a velocity of 6.6-6.8 km/s onshore, increasing by 0.2 km/s to the northeast offshore beneath the sedimentary basins. This seaward increase in velocity may be caused by intrusion of about 4 km of basic rocks into the lower crust during the extension that formed the overlying Carboniferous basins. The Moho is found at 34 km depth onshore, rising to 30 km offshore to the northeast with a local minimum of 27 km. The data confirm the absence of deep crustal roots under the central mobile belt of Newfoundland. Our long-range (up to 450 km offset) wide-angle data define a bulk velocity of 8.1-8.3 km/s within the upper 20 km of mantle. The data also contain strong reflective phases that can be correlated with two prominent mantle reflectors. The upper reflector is found at 50 km depth under central Newfoundland, rising abruptly towards the northeast where it reaches a minimum depth of 36 km. This reflector is associated with a thin layer (1-2 km) unlikely to coincide with a discontinuity with a large cross-boundary change in velocity. The lower reflector at 55-65 km depths is much stronger, and may have similar origins to reflections observed below the Appalachians in the Canadian Maritimes which are associated with a velocity increase to 8.5 km/s. Our data are insufficient for discriminating among various interpretations for the origins of these mantle reflectors.
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ΛΕΚΚΑΣ, Ε. Λ., Σ. Γ. ΛΟΖΙΟΣ, and Γ. Δ. ΔΑΝΑΜΟΣ. "Geological and tectonic structure of the area between Aigaleo and Parnitha Mt. (Attica, Greece) and their importance to antiseismic planning." Bulletin of the Geological Society of Greece 34, no. 1 (January 1, 2001): 19. http://dx.doi.org/10.12681/bgsg.16939.
Full textAbstract:
The September 7,1999 earthquake sequence hit the northwestern part of the basin of Athens (area between Aigaleo and Parnis Mt.), causing a large number of deaths and injuries, as well as extensive damage to structures. The major area represents a small basin which is covered by thick post-alpine formations, which are extended talus cones and, to a lesser extent, neogene lacustrine and fluvial deposits. The latter have been blanketed by the talus and the alluvial deposits at the north of the area. The basin is flanked by a hill range, where the non-metamorphic alpine carbonates of the "Sub-Pelagonian" Unit and an allocthonous tectonic melange that belongs to the "Athenian nappe" outcrop. The talus cones, with a thickness that ranges from a few m. to 100 m., contain frequent lateral transitions alternations of cohesive or semi-cohesive scree and loose deposits -sand, pebbles, gravel, clay, etc. The alluvial deposits consist of clay, red soils and conglomerates is clay matrix and have a thickness between a few m. and 20-30 m. The rieogene deposits comprise relatively compacted phacies of marls, marly limestones, clays and conglomerates. The alpine formations of both the autochton and the allocthon consist largely of carbonate rocks (limestones and marbles) and, to a lesser extend, of clastic deposits (sandstones, shales, schists, and graywackes). The main tectonic feature in the area is the contact between the two alpine units, located at the eastern margin. Besides this tectonic discontinuity, numerous other faults were located, either at the basin flanks, or within the postalpine formations. All these faults determined by a large number of boreholes. They are neotectonic structures that belong to two sets, one with NNW-SSE strike and 60°-80° WSWward or ESE-ward dips, and a second one with ESE-WNW strike and 60°-80° northerly or southerly dips. In fact, these faults are directly related to the creation and evolution of the small neogene basin, which is now buried under the talus scree and the alluvial deposits. It is a complex structure, since it incorporates smaller-scale horsts and grabens. The whole picture is in good accordance with the one we get from the greater area. The damage is located within a broad, NNE-SSW trending zone that covers the central and eastern parts of the area. The correlation of this picture with the geological and structural data from the studied area showed that the most serious damage took place on loose foundation formations, which were either the unconsolidated members of the talus cones, or the alluvial deposits. However, this was not the only factor that affected the damage distribution, since the heaviest damage was located (i) along the trace of the tectonic contact between the two alpine units, (ii) at the areas with higher fault density, usually close to the basin margins, but also locally within the basin. These faults were not reactivated in the September earthquake, but "channeled" the seismic energy into specific zones, which also holds, at a larger scale, for the greater meizoseismal area. Hanging wall effects, effects of sedimentary basins, basin edge effects and focusing effects are also probably to have played a significant part, at the locations where the fault geometry and the basin structure performed as reflectors, magnifying the effects of shaking and thus maximizing the strong ground motion values. Besides, the fact that the heaviest damage is located at the central and eastern part of the basin, where the fault fabric is denser and the faults better expressed, is not accidental.
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Yan, Jianhua, Jianping Chen, Jiewei Zhan, Shengyuan Song, Yansong Zhang, Mingyu Zhao, Yongqiang Liu, and Wanglai Xu. "Automatic identification of rock discontinuity sets using modified agglomerative nesting algorithm." Bulletin of Engineering Geology and the Environment 81, no. 6 (May 10, 2022). http://dx.doi.org/10.1007/s10064-022-02724-w.
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Chamlagain, Deepak, and Vishnu Dangol. "Landslide hazard evaluation in and around the Ilam Hydropower Project, Eastern Nepal Himalaya." Journal of Nepal Geological Society 27 (December 1, 2002). http://dx.doi.org/10.3126/jngs.v27i0.32009.
Full textAbstract:
The paper describes the results of the engineering geological and landslide hazard evaluation studies carried out in and around the Ilam Hydropower Project, eastern Nepal. Various types of mass wasting phenomena such as gully erosion, bank undercutting, and landslides are observed along the Mai Khola, Puwa Khola and road corridors. Gully erosion and bank undercutting are common on the slopes adjacent to streams and gullies. Most of the landslides are located on the slopes of 25° to 40° whereas large rock falls are found on the slopes, which are steeper than 40°. South-facing dip slopes contain large landslides while north-facing slopes seem to be relatively stable. The population of translational slide is dominant in the study area and is found mostly on soil having a depth of 3-6 m. Most of the rock falls are confined in schistose gneiss and highly fractured quartzite. Generally, three sets of joints govern the failure pattern of rockslides. The main triggering factors for mass movement of the area are high intensity of rainfall, rock discontinuities, steep topography, poor vegetation and river scouring. Land use pattern of the area has also equally contributed to initiate the mass movements in the area. The high hazard zones for rock slopes were confined to the steep dip slopes with highly fractured rocks whereas soil slope hazard is confined to fault zones and south facing slope. The soil slope was found to be more hazardous than the rock slope. The main causative factors for the landslide hazard in the study area are steep slope, rock discontinuity, land use pattern, soil depth and rainfall.