Journal articles on the topic 'Pile-rock interface'

The interface roughness between pile and rock in rock-socketed pile can influence its bearing mechanism largely. At present the numerical simulation, which simulates the interface roughness with changing the surface shape or interface friction coefficient, is used to study the interface roughness’ influence on pile’s bearing mechanism. It can reveal the pile bearing mechanism in some degree; however, there are some defects and limitations in simulation because of its assumptions and simplifications. Based on the pile foundation of Tian-xing-zhou Bridge, the model test is conducted to study the interface roughness’ influence on rock-socketed pile bearing mechanism. In the model test, the surface of model piles are made different ranging from smooth to rough, and the bed rock is simulated with mixture of sand and plaster, the rock-soil overlain the bed rock is simulated with silty sand, the pile is simulated with organic glass rod according to similarity principle respectively. The results show that load-settlement curves grow more gently, the ultimate bearing capacity is bigger, the proportion of point resistance is lower, and the shaft resistance is bigger which reaches more than 70% of total loading as the surface of pile is rougher. The conclusions are useful to deciding the length of pile foundation in Tian-xing-zhou Bridge.

This paper proposed a method for analysis of a drilled pile under vertical load at the crest of rock slope. Based on wedge theory, a modified model of normal stiffness of socket wall affected by the slope is obtained. Analyze the shear behaviors of the pile-rock interface, an analytical solution of load transfer of pile at the crest of rock slope is obtained. To evaluate the accuracy of the new method, this method is compared with the results of finite difference analysis. Finally, the method is used to analyze the effect of slope, pile, and rock properties on the unit side resistance and axial force.

This paper investigates the skin friction transfer characteristics of the rock-socketed section of a rock-socketed pile resting on thick sediment by conducting in situ core-drilling tests and static loading tests. Test results show that when using the impact hole-forming method in weakly cemented soil, a layer of sediment is deposited at the pile bottom. Due to the existence of sediment, when the load reaches a certain value, sudden and large subsidence is observed. This indicates that the end resistance does not contribute to the bearing capacity. Thus, it is not appropriate to consider both end resistance and side resistance in the existing design method of a rock-socketed pile. The bearing capacity of a single rock-socketed pile should be determined according to the side resistance of the soil layer and rock-socketed section only. Numerical analysis is performed to determine the deformation and load-carrying capacity of the pile and the distribution of friction on the sides of the rock-socketed segment. Under a given applied load, small settlement is observed when socketed thickness and rock strength are relatively large. The distribution of side friction of the socketed segment along the vertical direction shows a double-peak saddle shape. When the socketed thickness and rock strength are relatively smaller, the lower peak is higher than the upper peak, and conversely, when the socketed thickness and rock strength are relatively larger, the lower peak is smaller than the upper peak. For a given applied load on the pile top, smaller socketed thickness results in larger settlement and side friction. Due to the thick layer of sediment, the axial force of the rock-socketed segment of the pile gradually decreases along the vertical direction from the applied load on the pile top to zero at the bottom. According to the mechanical properties at different shear stages, a function is derived for the complete constitutive model for a pile-rock interface. Analytical solutions for the friction of a single pile are obtained under the conditions of failure and elasticity deformation of the surrounding rock. Its load transfer equation is derived as well. Accordingly, an equation is proposed for calculating the bearing capacity of rock-socketed piles resting on sediment at the bottom.

To investigate the treatment effect of micro-piles on uplift deformation of red-bedded soft rock subgrade, an in-situ static load test of slurry injected steel pipe micro-piles with different length was carried out, the uplift bearing capacity and deformation characteristics of micro-piles were analyzed, and the load transfer function of pile lateral friction resistance was modified with the consideration of pile length. A numerical simulation method considering the variable shear stiffness at the pile-soil interface was established, and the inversion of the relevant material parameters was carried out based on the in-situ test results. Through numerical simulation, the effect of single piles with different pile lengths and group piles with different pile spacing on the treatment of the uplift deformation of the subgrade was investigated. Finally, the anti-uplift design method of micro-piles in red-bedded soft rock was proposed. The results show that the uplift bearing capacity increased nonlinearly with the increase in pile length, and the variation curve of pile lateral friction resistance with pile-soil relative displacement showed a hardened type. The predicted pile lateral friction resistance shows a good correlation with the measured result; all the correlation coefficients were greater than 0.81. The uplift deformation of subgrade without piles was radially distributed with the maximum value of 5.12 mm as the center. A single micro-pile with a length of 7 m or a rectangular array of group piles with a length of 7 m and a spacing of 3D could effectively decrease the maximum uplift deformation to less than 4.0 mm, which can meet the requirement of specification. Thus, the micro-piles could be used for controlling the uplift deformation of red-bedded soft rock subgrade, and this study can provide a reference for anti-uplift design in the distributed area of red-bedded soft rock.

Construction operations in cold regions may encounter frozen geomaterials. In construction, it is important to understand the processes by which geomaterials fail under common loading conditions to avoid accidents and work efficiently. In this work, an artificial frozen soil–rock mixture was used for uniaxial compression and indirect tension loading analysis to investigate macroscopic failure patterns and soil–rock interface crack evolution mechanisms. To further understand and compare the meso-mechanical failure mechanisms of the soil–rock interface, we used two types of rock block particles with different surface roughness for fabricating frozen artificial soil–rock mixtures. Acoustic emission (AE), ultrasonic plus velocity (UPV), and digital microscopy were utilized here to obtain the sample deformation response and analyze the morphology of the soil–rock interface. The results were as follows. From the perspective of macroscopic observation, bulging deformations and short tension cracks represent the main failure pattern under compression, and a tortuous tension crack in the center of the disk is the main failure pattern under indirect tension. From the perspective of microscopic observation, the soil–rock interface will evolve into a soil–rock contact band for the sample containing a rough rock block. The strength of the soil–rock contact band is obviously larger than that of the soil–rock interface. Three main failure patterns of the soil–rock interface were observed: a crack path through the accurate soil–rock interface, a crack path through the envelope of the rough rock block, and a crack path passing through the rough rock block. The experimental results could provide a reference for foundation engineering, especially in pile foundation engineering in cold regions.

A detailed manufacturing procedure of a synthetic soft rock is presented, as well as its applications on the laboratory experiments of socketed piles. With the homogeneity and isotropy of the simulated soft rock, the influence of different variables on the bearing performance could be investigated independently. The constituents, cement, gypsum powder, river sand, concrete-hardening accelerator, and water, were mixed to form the specimens. Both uniaxial and triaxial compressive tests were conducted to investigate the stress-strain behavior of the simulated soft rock. Additionally, the simulated soft rock specimens were used in model pile tests and simple shear tests of the pile-rock interface. Results of the simulated soft rock in both the uniaxial and triaxial compressive tests are consistent with those of natural soft rocks. The concrete-hardening accelerator added to the mixtures improves the efficiency in laboratory investigations of soft rock specimens with a curing time of 7 days. The similarities between the laboratory tests and the field observations provide convincing evidence to support its suitability in modeling the behavior of soft rocks.

The self-balanced loading test is a state-of-art pile testing method, but its suitability to pile bearing capacity determination in transformer substation engineering in mountainous and hilly areas is not yet clear. In this study, a two-dimensional axisymmetric numerical model is established by the PLAXIS software to simulate the behavior and bearing mechanism of shallow rock-socketed short piles based on the self-balanced loading test. The model is first validated by simulating the field tests of two adjacent piles under self-balanced loading. Then the influence factors of the load-displacement curves of piles are analyzed. Thereafter, the mechanical mechanism of the self-balanced loading tests is simulated and compared with the conventional static loading tests. It is observed that the rock modulus, rock-socketed depth of piles, and burial depth of the Osterberg Cell affect the load-displacement significantly, but the cohesion of the rocks affects little. Moreover, compared with the conventional static loading tests, the shear stress of the pile-soil interface distributes less uniformly under self-balanced loading conditions. On this basis, a bearing capacity computation method of shallow rock-socketed short piles based on the self-balanced loading test is proposed.

A technical solution for tidal turbine foundation in granite seabed consists of grouted steel piles. The piles would be subjected to cyclic loading due to the severe service conditions. The mechanical behaviour at the interface between the pile and the surrounding media is one of the key points that determine the bearing capacity of the foundation system. Experimental research work has been carried out in the laboratory to study the grouted pile-to-rock connection (GPRC) and focused more precisely on the pile to grout connection when the pile is equipped with shear-keys that enhance the interface capacity. Monotonic and cyclic shear tests were performed using a specific direct shear test device (BCR3D), allowing application of sample confining conditions close to the in-situ conditions, namely constant normal stiffness conditions. Cyclic tests - either under one way or two-way shear loading application - were performed on several samples, under both constant volume and various constant stiffness boundary conditions. This study has shown that the strength of the interface is highly dependent on the combination of mean load, cyclic amplitudes and number of cycles applied to the interface. Cyclic failure was observed with less than 30 cycles for two-way and one-way cyclic loading.

In the waterway construction projects of the upper streams of the Yangtze River, crushed mudstone particles are widely used to backfill the foundations of the rock-socketed concrete-filled steel tube (RSCFST) pile. The mudstone particles are prone to being crushed, which influences the mechanical properties of the soil and the interface between the soil and the steel cased on the RSCFST pile. The crushing of the particles will be aggravated by reciprocating shear of the interface when the pile experiences repeating lateral loads. The reciprocating shear of the interface may, therefore, weaken the bearing capacity of the pile. In this study, we develop a new apparatus to study the mechanical properties of the steel–soil interface under a reciprocating shear condition. With this apparatus, a set of large-scale direct shear experiments are carried out with two different boundary conditions, that is, a constant stress boundary and a constant stiffness boundary, respectively. Comparative experiments and parallel experiments are carried out to study the physical properties of steel–mudstone particle interface and the stability of the apparatus. Parallel experiments show that the instrument has good stability. The comparative experiment results also reveal the differences of the shear behaviors of the interface under two conditions. Analysis of the experiment results shows that the normal stiffness condition is closer to the real boundary condition when the soil–steel interface is cyclically sheared. The particle crushing and the attenuation of normal stress is the main reason causing the degrading of the interface.

Taking the deformation of row pile supporting structure of foundation pit in strata with rock-soil combination as the research target and taking an open cut metro deep foundation pit as an example, by in-site monitoring and numerical simulation, analyze the horizontal displacement of retaining piles and the change law of steel support axial force in the strata with rock-soil combination, and summarize the change law of row pile supporting structure in the process of excavation under the conditions of this strata, so that to provide experience and guidance for similar engineering design and construction. The results show that: the structure of foundation pit has obvious effects on deformation and internal force of supporting structure, the result obtained from numerical simulation fits well with the tendency of monitoring data changing. In which, the deformation of row pile supporting structure in the middle and upper part of soil strata is larger, the deformation of middle and lower part of soil strata is comparatively smaller, the lateral deformation of row piles to basement has a tendency of gradual decreasing by taking the interface of rock-soil as a boundary.

The mechanical properties of interface between soil-macadam aggregate and anti-sliding concrete pile are very important for the reinforcement design and safety evaluation of accumulative landslide in the reservoir area of Three Gorges. Soil-macadam aggregate is a complex geomaterial whose properties are totally different with soil or rock. Based on a practical landslide suffering the influence of reservoir water level change and seasonal rainfall, a series of direct shear tests are conducted to investigate the interface mechanical properties between soil-macadam aggregate and concrete pile. Accordingly, the relationship between shear strength parameters and water contents and macadam ratios is presented. The change characteristics of mechanical properties of interface are discussed. The results indicate that shearing strength, inner friction angle and cohesion decrease with less water content. However, as the increment of macadam ratios, the cohesion will decrease gradually, but the shear strength and inner friction angle of interface decrease firstly and then increase after a critical value, the change trend obeys parabolic relation.

AbstractThe development and construction of offshore wind farms requires the correct estimation of the friction that can be mobilised at the rock/grout interface. In conventional studies, the shear behaviour of a joint is usually investigated with laboratory tests under constant normal load/stress (CNL), however, in engineering practice, direct shear testing under constant normal stiffness (CNS) has been proved to be more realistic in the assessment of the development of the side shear resistance in rock grouted pile design. In this work, an extensive experimental campaign on the shear response of a weak carbonate rock (limestone) interface with grout is presented, in the frame of offshore wind turbines. First, basic mechanical testing is performed on the two interface materials in order to evaluate their mechanical properties. The output of these tests reveals not only the contrasting properties of the two interacting materials, but also the decreased response of the limestone in the presence of water. A series of monotonic shear tests (both under CNL and CNS conditions) on wet rough limestone/grout interfaces reveal the high impact of adhesion between the two materials to the mechanical response. Based on the monotonic results, a number of CNS shear tests under cyclic loading takes place, where different failure modes are observed dilatant and contractant response. The variability of the failure mode is strongly related not only to the adhesion created with the cast grout, but also to the limestone’s micro-structural heterogeneity that manifests already after consolidation. The post-shear morphological state of the interface is analysed, while the variability of the failure surface and the presence of water gouge creation do not allow a clear correlation of the morphologfy to the mechanical response. Overall, the response of this type of weak rock interface where the properties of the grout are significantly higher, is governed by the behaviour of the rock.

Prediction of rock socket shaft resistance is a complex problem. Conventional methods for predicting the peak shaft resistance are typically empirically related to unconfined compressive strength through the results of pile load tests. It is shown by reference to international pile socket databases that the degree of confidence which can be applied to these empirical methods is relatively low. Research at Monash University has been directed at understanding and then modelling the complex mechanisms of shear transfer at the interface between the socketed piles and the surrounding rock. Important factors that affect the strength of pile sockets have been identified in laboratory and numerical studies. With a knowledge of the effect of these factors, the reasons for the large scatter around traditional empirical correlations can be deduced. A computer program called ROCKET has been developed which encompasses all aspects of the Monash University rock socket research. This program has been used to develop design charts for rock-socketed piles based on unconfined compressive strength and a nondimensional factor which has been designated the shaft resistance coefficient (SRC). Implementation of the SRC method in design requires an estimate of the likely socket roughness to be made. Very few researchers or practitioners have measured socket roughness, so there is little available guidance in selection of appropriate values. Although many socket load tests are described in the technical literature, the physical parameter which is regularly missing is the socket roughness. With a knowledge of the shaft resistance, and an estimate of all other relevant parameters, the authors have been able to back-calculate the apparent socket roughness using the SRC method. Based on the back-calculated roughness data, socket roughness guidelines for use in analysis and design of rock sockets have been proposed. Using these roughness guidelines, it is shown that the SRC method is able to predict the scatter observed in previously published international load test databases.Key words: rock socket, drilled shaft, shaft resistance, roughness, shaft resistance coefficient.

Karst geological anomalies at pile locations significantly affect the bearing capacity and construction safety of the piles, posing a significant challenge for urbanization. Borehole geophysical methods are required to extend the detection range and identify karst voids that are at pole locations and near drilled boreholes. In this paper, we developed a near offset and small diameter single borehole ground penetration radar (GPR) prototype. A signal processing method combining complex signal analysis by Hilbert transform (HT) and medium filtering was suggested to differentiate the weak backscattered wave from borehole background noise. A controlled horizontal borehole experiment was used to demonstrate the applicability of the prototype and the advantages of the signal analysis method prior to application in a real project. The controlled test presented three typical wave events corresponding to a soil–rock interface, rock fractures, and karst voids. Field tests were conducted at a freeway bridge extension project in an urban karst area. Multiple karst voids, sinkholes, rock fractures, and integrated bedrock were identified by analysis of four typical detection scenarios. The remediation of the karst voids and a rotary bored piling with real-time steel casing construction strategy were designed based on the investigation results. The construction feedback demonstrates that single borehole radar detection is effective for the investigation of anomalies at pile locations in urban karst areas.

Abstract To study the influence of the nonlinear connection of pile and soil on the dynamic response characteristics of the pile foundation, this article proposes to study the dynamic response of the bridge pile foundation to the slope by combining the centrifugal shaking table test and OPENSEES open source finite element program. This article introduces the pressure-dependent multiyield surface model based on confining pressure. Through the inverse calculation of the similarity ratio of the centrifuge model test, the OPENSEES two-dimensional nonlinear finite element model of the pile group in the slope section can be established. The centrifuge shaking table test is to input the preset seismic wave horizontally at the bottom of the model box. The form of seismic wave is El Centro wave verification of two-dimensional finite element model of the pile group in slope section under earthquake. The reliability of the model is verified by comparing the test and calculated values of dynamic response (residual horizontal displacement and final bending moment) of the pile body under five different peak acceleration seismic wave loading conditions. In the dynamic response experiment of slope pile foundation, in the embedded part below the bedrock surface, the residual horizontal displacement of each pile body is zero. Constrained by the cap beam and tie beam, the displacement of the free section of the pile group at these two positions is basically the same. Through comprehensive analysis, the displacement of P1 and P2 piles is basically the same. The calculated value of the final bending moment of P1 and P2 piles shows the same change trend as the test value, and the test value is slightly larger than the calculated value. The relative errors of the maximum final bending moment of P1 pile under each loading condition are 7.4, 7.8, 12.6, 3.9, and 9.6%, respectively, and the relative errors of P2 pile are 4.6, 3.6, 12.5, 13.6, and 11.5%, respectively. The analysis relative error is caused by the elastic element used in the calculation of the pile body, which is different from the mechanical behavior of the simulated pile body material in the test. Dynamic response of slope site according to the existing centrifuge test results can be seen that the deformation at the slope shoulder of slope site is the most obvious under the earthquake. The inclined interface of soft and hard rock and soil layer will aggravate the dynamic response of the overburden layer on the slope, weakening its ability of seismic energy consumption.

[ID] Pondasi sebagai dasar bangunan harus mampu memikul seluruh beban bangunan dan beban lainnya, untuk diteruskan sampai kelapisan tanah atau batuan dibawahnya. Pemilihan jenis pondasi salah satunya disebabkan oleh jenis tanah dan jenis struktur atasnya, apakah termasuk konstruksi beban ringan atau beban berat, maka dari itu diperlukan stabilitas tanah itu sendiri agar mempunyai kapasitas dukung yang kuat. Tujuan dari penelitian ini menghitung kapasitas dukung aksial, kapasitas dukung lateral, penurunan, defleksi pondasi bored pile menggunakan metode statis dan elemen hingga 2D, menghitung tegangan geser efektif tanah dengan metode elemen hingga 2D yang kemudian membandingkan dengan beban bekerja dan syarat yang diizinkan. Dalam menganalisa beban bekerja pada bangunan dihitung menggunakan bantuan software Etabs v.9. Analisa kapasitas dukung pondasi bored pile tunggal menggunakan metode Aoki & Alancer, Schmertmaan & Nottingham, Begemaan, dan untuk menghitung kapasitas dukung pondasi bored pile (group) digunakan efisiensi kelompok tiang, sedangkan kapasitas lateral dan defleksi digunakan metode Broms dan penurunan pondasi bored pile tunggal menggunakan metode Dee Beer & Marten, untuk kelompok tiang menggunakan metode Vesic dan tegangan geser efektif tanah. Dan akan dilakukan analisa menggunakan elemen hingga 2D dengan bantuan software Plaxis 2D v.8.2. Dari hasil perhitungan dan persentase nilai terbesar kapasitas dukung (Qgall) pondasi bored pilegroup As I-39 dan As C-26 pada titik S-1 dengan metode Schmertmaan & Nottingham sebesar 128%, metode Begemaan sebesar 139% dan elemen hingga 2D sebesar 169% dan dinyatakan pondasi aman terhadap beban yang bekerja pada pile cap, sedangkan metode Aoki & Alancer sebesar 39%, dinyatakan tidak aman terhadap beban yang bekerja pada pile cap. Dan kapasitas beban lateralmetode Broms mampu memikul sebesar 167% dan elemen hingga 2D sebesar 105% dan dinyatakan aman terhadap beban horizontal yang bekerja. Sedang defleksi pondasi bored pile metode Broms sebesar 2,39 mm, elemen hingga 2D sebesar 3,46 mm, dan penurunan pondasi tunggal dengan metode Dee Beer & Marten sebesar 9,78 mm, elemen hingga 2D sebesar 36,40 mm dan pondasi bored pile group metode Vesic sebesar 21,87 mm dan elemen hingga 2D sebesar 16,78 mm, dapat dinyatakan defleksi dan penurunan memenuhi syarat yang diizinkan, dan tegangan geser efektif tanah tunggal tanpa interface dan dengan interface tidak memenuhi syarat yang diizinkan. [EN] Foundation, as the building basic must be able to carry the whole building load and other loads to be forwarded to the soil or rock layers underneath. Selection of the foundation type one caused by the type of soil and the type of structure above, whether included construction of a light load or a heavy load, therefore it needed the stability of the land itself in order to have a strong bearing capacity. The purpose of this studies are to calculate the axial bearing capacity, lateral bearing capacity, decreasing, and bored pile foundation deflection using static and 2D finite element method, and calculate effective shear stress of soil with 2D finite element method, then compare with the workload and terms are allowed. In analyzing the workload on buildings, the calculation using ETABS software v.9. Analysis of bearing capacity of single bored pile foundation use Aoki & Alancer, Schmertmaan & Nottingham, Begemaan method, and to calculate the bearing capacity of bored pile foundation (group) used the pile groups efficiency, while lateral capacity and deflection used Broms method and reduction single bored pile foundation used Dee Beer & Marten method, for pile group using Vesic method and effective shear stress of soil. And will be analyzed using 2D finite element with Plaxis 2D software v.8.2. From the calculation and the percentage of the bearing capacity greatest value (Qgall), bored pile group foundation As I-39 and As C-26 at S-1 point with Schmertmaan & Nottingham method amounted to 128%, Begemaan method amounted to 139% and the 2D finite element amounted to 169 % and foundation declared safe to the load on the pile cap, whereas Aoki and Alancer method amounted to 39%, declared unsafe to load on the pile cap. And the lateral load capacity Broms method capable of assuming at 167% and the 2D finite element about 105% and declared safe to horizontal workload. Bored pile foundation deflection with Broms method amounted to 2.39 mm, 2D finite element amounted to 3.46 mm, and a decrease in single foundation with Dee Beer & Marten method amounted to 9.78 mm, 2D finite element amounted to 36.40 mm and bored pile group foundation Vesic method amounted to 21.87 mm and 2D finite element amounted to 16.78 mm, it can be stated that deflection and decrease are eligible permitted, and effective shear stress of single soil with and without interface are ineligible permitted.

In this study, a three-dimensional finite element model was established to simulate the dynamic response of a large-scale steel-reinforced concrete composite high-pile wharf with a rock-socketed steel sheath. The model is based on the second phase of the Chongqing Orchard Harbor structure project in conjunction with the project “Research on the mechanism of interface damage and energy dissipation of the structure of the large-scale steel-reinforced concrete composite high-pile wharf in inland waters.” The stiffness of frame wharf is studied from the perspective of modal and transient dynamic analysis of structural dynamics. The distribution of the low-order modal frequency is more uniform. With the increase of the order, the modal frequency of the structure shows a periodical jump. The overall stiffness of the frame structure is larger with the steel sheath, and the longitudinal stiffness is less than the transverse stiffness. Under the action of transverse impact load, the members and joints of the steel-concrete structure exhibit synchronous mechanical response characteristics in the time domain. The peak values of displacement and stress of the structural joints occur 0.05 s after the peak value of the load-time history, and the peak value of reverse response of force occurs at 2.3 s, which is markedly smaller than the peak value of the response of load direction. Reducing the local positional stiffness of the load point is beneficial to improve the stress of the entire structure. The weak links of the frame structure appear at the joints of the members. Because of the hoop action of the steel sheath, the stress of the reinforced concrete pile core is more uniform. The peak value of the equivalent stress of the steel sheath member is generally larger than that of the reinforced concrete pile core, and the stress is highly concentrated at the joints of the steel tube longitudinal and transverse braces.

ABSTRACT In modern ooid-forming environments in the Caribbean, aerobic respiration of organic matter below the sediment–water interface drives an increase in pCO2 and a corresponding decrease in carbonate saturation state (Ω) that creates shallow sediment porewater that is neutral or slightly caustic to carbonate. The locus of ooid growth, therefore, is presumed to be in the water column during suspension, where supersaturation with respect to calcium carbonate is the norm. In the past, however, during conditions of low aqueous O2, high Ω, or low organic-matter input, the shallow sub-sediment marine burial environment was conducive to carbonate precipitation. Here we present petrographic and electron probe microanalyzer (EPMA) data from exquisitely preserved oolites through time that suggests that some ancient ooids may have grown within the sediment pile. We propose that each increment of ooid cortical growth originated as incipient isopachous marine cement formed during shallow burial within migrating ooid dunes. After a period of burial (∼ weeks to months), ooids were remobilized and rounded during bedload transport. This “bedform model” for ooid growth explains: 1) why ancient ooids are not limited by the precipitation–abrasion balance that appears to prohibit modern tangential Caribbean ooids from achieving grain sizes larger than coarse sand, 2) the radial crystal fabric that defines the internal structure of many ancient ooids, and 3) the first-order correlation of the abundance of large and giant ooids in the rock record to periods with predicted high porewater Ω. This model implies that photosynthetic microbes were unimportant for growth of large and giant ooid but it remains agnostic to the effect of other microbes. The physical and chemical milieu of modern marine ooid-forming environments is perhaps not the best analogue for ancient ooid-forming environments; this should be considered when using ancient ooids to reconstruct secular trends in ocean chemistry.

The stability and deformation characteristics of the pile foundation in the Karst region of the super big railway bridge Chaogou under different loading levels are analyzed using the FDM-software, FLAC3D. In the analyses the socketed depth of piles, the properties of soil and rock mass, the scale, space position and filling situation of the Karst caves and the features of the contact interfaces between piles and soil and rock mass were taken into account. The research results show that the original design of the pile foundation is safe and the safety coefficient is greater than 2. The bond strength of the contact surface between pile and soil and rock is a controlling factor for the stability of pile foundation. Therefore, injection after construction is suggested to be used when needed, in order to increase the bond strength of the contact surface. The research leads to a conclusion that the mechanisms and the characteristics of the rock socketed piles can be more clearly interpreted in numerical analyses by referring the principle of the interaction between piles and rock, pile foundation and Karst, resistance of both pile ends and sides.

The Soil Improved shearing displacement law is used to analyze Pile-soil interaction and this method can consider stratified foundation, but can’t consider pile-soil slip. An improved shearing displacement law analyzing pile-soil interaction was proposed in this article which could think over pile-soil slip on interfaces and interaction of pile-soil on stratified foundation. Rock and soil’s parameter is very crucial in geological engineering, the soil parameters were determined by parameter back analysis theory and the stress and deformation characteristic for vertical loading piles were analyzed by the improved shearing displaces law. These process was simulated by my own program. The calculation results show that the axial force of pile decreases with pile depth and the pile tip axial force is zero. The pile bottom resistance increases with load and the soil’s resistance increases with the relative displacement between pile and soil. But,the frictional resistance growth rate with displacement is different in different soil. The silt’s growth rate is minimum and the medium-fine sand mixed mucky soil is maximum. The pile frictional resistance increases with load and depth. It has greater directive significance for the pile design.

Abstract High pressure–low temperature metamorphic rocks from the late Paleozoic accretionary wedge exposed in central Chile (Pichilemu region) are characterized by a greenschist-blueschist lithological association with interbedded metasediments that reached peak burial conditions of ∼400 °C and 0.8 GPa during late Carboniferous times. We herein combine new extensive field observations, structural measurements, and geochemical and petrological data on vein and matrix material from Pichilemu transitional greenschist-blueschist facies rocks. The studied veins were first filled by albite, followed by quartz and calcite as well as glaucophane and winchite. Field, structural, and microscopic zoning patterns show that these rocks underwent a protracted sequence of prograde vein-opening events, which have been largely transposed to the main foliation before and during underplating in the basal accretion site near 25–30 km depth. While some of the earliest albite-filled vein sets may have formed after prograde breakdown of sub–greenschist facies minerals (<250 °C), our thermodynamic modeling shows that relatively minor amounts of fluid are produced in the subducted pile by dehydration reactions between 250 and 400 °C along the estimated geothermal gradient. It also confirms that the formation of interlayered blueschist and greenschist layers in Pichilemu metavolcanics is a consequence of local bulk composition variations, and that greenschists are generally not formed due to selective exhumation-related retrogression of blueschists. The early vein sets are a consequence of prograde internal fluid production followed by sets of hydrofractures formed at near-peak burial that are interpreted as a record of external fluid influx. We postulate that such a fractured sequence represents a close analogue to the high-Vp/Vs regions documented by seismological studies within the base of the seismogenic zone in active subduction settings.

AbstractRock-socket pile design predominantly depends on the shaft resistance to support the load at the serviceability state. However, due to limited understanding of the pile–rock interactions, the pile capacity is normally calculated using empirical correlations. In this study, the load-bearing mechanisms of rock-socketed piles were investigated through a miniaturised pile–load test setup in a soft synthetic rock. X-ray CT imaging and numerical discrete element modelling were used to investigate the micro-mechanics influencing the load-bearing mechanisms at the pile–rock interface. The numerical pile model was established based on suitable constitutive models capable of simulating the soft rock behaviour. The analysis of X-ray CT images at various displacements revealed three different interface mechanisms, namely sliding, local shearing and progressive shearing. The numerical model validated this observed micro-mechanics in the rock asperities through the evolution of damage and micro-cracks. Insights from the experimental and numerical results indicated that the height of the rock asperities significantly dictates the failure mode. Results also illustrated that the shaft load–displacement response primarily depends on the forces acting on the leading edges of the pile asperity. In particular, it was observed that the bottom leading edge carried a predominant portion of the shaft loads due to its connectivity with the rock at the base of the pile. Though negligible, the forces on the trailing edges provided valuable information on the contribution of residual shaft resistance by the debris at the interface. Moreover, the numerical studies revealed the different failure modes at the pile–rock interface. The discussions presented in this study provide novel insights into the load-bearing mechanisms of piles socketed in soft rocks, which will help to improve design guidelines in the future.

The wave transformation due to pile-rock porous structure in combination with vertical porous barrier is studied under oblique wave action. The pile-rock breakwaters consists of two rows of closely spaced piles and a rock core between them is effective in dissipating wave energy when compared with traditional rigid breakwaters due to its reduced deadweight of construction materials and additional stability. Three different cases of the vertical barrier configurations such as fully-extended barrier, bottom-standing barrier and surface-piercing barrier placed in front of the pile-rock porous structure are considered for the investigation. The numerical study is performed using the eigenfunction expansion and the associated orthogonal mode-coupling relations considering the continuity of pressure and velocity for the vertical barrier, seaward and leeward structural interfaces. The Darcy’s law is incorporated for the flow through porous media and the porosity factor of the structure is introduced using the complex porous effect parameter. The numerical results for the wave reflection, transmission and dissipation coefficient, wave force on front and rear side of porous structure along with the wave force on the barrier interface are evaluated for different hydraulic characteristics. The analysis is presented for varying structural porosity, angle of incidence, structural thickness, friction factor, length between vertical barrier and porous structure for the three different cconfigurations of vertical barrier. The numerical investigation performed in the present study will be useful for the design and analysis of the composite breakwater system to protect the offshore facility from high waves.

The determination of internal pile reactions is critical to designing and assessing the structural performance of deep foundations. Internal shear and moment profiles strongly depend on lateral pile-soil interaction, which in turn depends on pile and soil stiffnesses as well as the stiffness contrast between soft and stiff strata, such as occurs at a soil/rock interface. At zones of strong geomaterial stiffness contrast, Winkler-spring-type analyses predict abrupt changes in the internal pile reactions for laterally-loaded foundation elements. In particular, the sudden deamplification of internal moments when transitioning from a soft to stiff layer is accompanied by amplification of pile shear. This “shear spike” can result in bulky transverse reinforcement designs for drilled shaft rock sockets that pose constructability challenges due to reinforcement congestion, increasing the risk of defective concrete on the outside of the cage. This paper presents an experimental research program of three large-scale, instrumented drilled shafts with simulated rock sockets constructed from concrete. Each shaft had a different transverse reinforcement design intended to bound the amplitude of the predicted amplified shear demand, with a particular emphasis on performance of shafts with shear resistance less than the predicted demand and below the code minimum. Test results suggested that the shafts experienced a flexure-dominated failure irrespective of the transverse reinforcement detailing.

In this article, a centrifuge shaking table model test of anchored stabilizing piles for strengthening landslides was established, and the dynamic response characteristics of the pile–anchor–slope under earthquake action were analyzed. On this basis, combined with the fuzzy gray relational analysis and the rank-sum ratio method, the correlation between the amplification of the acceleration response of the heterogenous slope and the dynamic response of the support structure was explored. Based on the obtained results, relevant suggestions for engineering design were proposed. The results showed that the seismic amplification of the complex soil–rock slope reinforced by the pile–anchor structure was not uniform and the amplification coefficient had strong variability. Among them, the amplification coefficient of the slope, dynamic earth pressure, and dynamic bending moment of the pile near the connection of the pile–anchor cable continued to increase; the correlation between the seismic amplification and the seismic behavior of the pile–anchor structure is different at different positions of the slope. The measurement points with a higher comprehensive ranking of correlation are mainly concentrated in the pile–anchor connection, the middle of the slope, and the high-angle soil–rock interface. It is related to the geometric characteristics of the model and the high seismic amplification of the slope; for the pile–anchor connection part and the high-angle soil–rock structure surface of the slope, the shock absorption measures and grouting strength of the anchor cable’s anchoring section should be considered in the engineering design.

Of Motivational Art “Live to be outstanding.” What is new media in the age of the ‘rock ‘n’ roll life coach’ Anthony Robbins? There is no need to be ‘spectacular’ anymore. The Situationist critique of the ‘spectacle’ has worn out. That would be my assessment of the Robbins Age we now live in. Audiences are no longer looking for empty entertainment; they need help. Art has to motivate, not question but assist. Today’s aesthetic experience ought to awaken the spiritual side of life. Aesthetics are not there for contemplation only. Art has to become (inter)active and take on the role of ‘coaching.’ In terms of the ‘self mastery’ discourse, the 21st Century artist helps to ‘unleash the power from within.’ No doubt this is going to be achieved with ‘positive energy.’ What is needed is “perverse optimism” (Tibor Kalman). Art has to create, not destroy. A visit to the museum or gallery has to fit into one’s personal development program. Art should consult, not criticize. In order to be a true Experience, the artwork has to initiate through a bodily experience, comparable to the fire walk. It has to be passionate, and should shed its disdain for the viewer, along with its postmodern strategies of irony, reversal and indifference. In short: artists have to take responsibility and stop their silly plays. The performance artist’s perfect day-job: the corporate seminar, ‘trust-building’ and distilling the firm’s ‘core values’ from its ‘human resources’. Self-management ideology builds on the 80s wave of political correctness, liberated from a critical negativism that only questioned existing power structures without giving guidance. As Tony says: “Live with passion!” Emotions have to flow. People want to be fired up and ‘move out of their comfort zone.’ Complex references to intellectual currents within art history are a waste of time. The art experience has to fit in and add to the ‘personal growth’ agenda. Art has to ‘leverage fears’ and promise ‘guaranteed success.’ Part therapist, part consultant, art no longer compensates for a colourless life. Instead it makes the most of valuable resources and is aware of the ‘attention economy’ it operates in. In order to reach such higher plains of awareness it seems unavoidable to admit and celebrate one’s own perverse Existenz. Everyone is a pile of shit and has got dirty hands. Or as Tibor Kalman said: “No one gets to work under ethically pure conditions.” (see Rick Poynor’s <http://www.undesign.org/tiborocity/>). It is at that Zizekian point that art as a counseling practice comes into being. Mapping the Limits of New Media To what extent has the ‘tech wreck’ and following scandals affected our understanding of new media? No doubt there will also be cultural fall-out. Critical new media practices have been slow to respond to both the rise and the fall of dotcommania. The world of IT firms and their volatile valuations on the world’s stock markets seemed light years away from the new media arts galaxy. The speculative hey-day of new media culture was the early-mid 90s, before the rise of the World Wide Web. Theorists and artists jumped eagerly at not-yet-existing and inaccessible technologies such as virtual reality. Cyberspace generated a rich collection of mythologies. Issues of embodiment and identity were fiercely debated. Only five years later, with Internet stocks going through the roof, not much was left of the initial excitement in intellectual and artistic circles. Experimental technoculture missed out on the funny money. Over the last few years there has been a steady stagnation of new media culture, its concepts and its funding. With hundreds of millions of new users flocking onto the Net, the arts could no longer keep up and withdrew to their own little world of festivals, mailing lists and workshops. Whereas new media arts institutions, begging for goodwill, still portray artists as working at the forefront of technological developments, collaborating with state of the art scientists, the reality is a different one. Multi-disciplinary goodwill is at an all time low. At best, the artist’s new media products are ‘demo design’ as described by Peter Lunenfeld in Snap to Grid. Often it does not even reach that level. New media art, as defined by its few institutions, rarely reaches audiences outside of its own subculture. What in positive terms could be described as the heroic fight for the establishment of a self-referential ‘new media arts system’ through a frantic differentiation of works, concepts and traditions, may as well be classified as a dead-end street. The acceptance of new media by leading museums and collectors will simply not happen. Why wait a few decades anyway? The majority of the new media art works on display at ZKM in Karlsruhe, the Linz Ars Electronica Center, ICC in Tokyo or the newly opened Australian Centre for the Moving Image are hopeless in their innocence, being neither critical nor radically utopian in approach. It is for that reason that the new media arts sector, despite its steady growth, is getting increasingly isolated, incapable of addressing the issues of today’s globalized world. It is therefore understandable that the contemporary (visual) arts world is continuing the decades old silent boycott of interactive new media works in galleries, biennales and shows such as Documenta. A critical reassessment of the role of arts and culture within today’s network society seems necessary. Let’s go beyond the ‘tactical’ intentions of the players involved. This is not a blame game. The artist-engineer, tinkering away on alternative human-machine interfaces, social software, or digital aesthetics has effectively been operating in a self-imposed vacuum. Over the last few decades both science and business have successfully ignored the creative community. Even worse, artists have actively been sidelined in the name of ‘usability’. The backlash movement against web design, led by usability guru Jakob Nielsen, is a good example of this trend. Other contributing factors may have been fear of corporate dominance by companies such as AOL/Time Warner and Microsoft. Lawrence Lessig argues that innovation of the Internet itself is in danger. In the meanwhile the younger generation is turning its back from new media arts questions and operates as anti-corporate activists, if at all engaged. Since the crash the Internet has rapidly lost its imaginative attraction. File swapping and cell phones can only temporarily fill the vacuum. It would be foolish to ignore this. New media have lost their magic spell; the once so glamorous gadgets are becoming part of everyday life. This long-term tendency, now in a phase of acceleration, seriously undermines the future claim of new media altogether. Another ‘taboo’ issue in new media is generationalism. With video and expensive interactive installations being the domain of the ‘68 baby boomers, the generation of ‘89 has embraced the free Internet. But the Net turned out to be a trap for them. Whereas real assets, positions and power remains in the hands of the ageing baby boomers, the gamble of its predecessors on the rise of new media did not materialize. After venture capital has melted away, there is still no sustainable revenue system in place for the Internet. The slow working education bureaucracies have not yet grasped the new media malaise. Universities are still in the process of establishing new media departments. But that will come to a halt at some point. The fifty-something tenured chairs and vice-chancellors must feel good about their persistent sabotage. ‘What’s so new about new media anyway? Technology was hype after all, promoted by the criminals of Enron and WorldCom. It’s enough for students to do a bit of email and web surfing, safeguarded within a filtered and controlled intranet…’ It is to counter this cynical reasoning that we urgently need to analyze the ideology of the greedy 90s and its techno-libertarianism. If we don’t disassociate new media quickly from that decade, if we continue with the same rhetoric, the isolation of the new media sector will sooner or later result in its death. Let’s transform the new media buzz into something more interesting altogether – before others do it for us.The Will to Subordinate to Science The dominant wing of Western ‘new media arts’ lacks a sense of superiority, sovereignty, determination and direction. One can witness a tendency towards ‘digital inferiority’ at virtually every cyber-event. Artists, critics and curators have made themselves subservient to technology – and ‘life science’ in particular. This ideological stand has grown out of an ignorance that cannot be explained easily. We’re talking here about a subtle mentality, almost a taboo. The cult practice between ‘domina’ science and its slaves the new media artists is taking place in backrooms of universities and art institutions, warmly supported by genuinely interested corporate bourgeois elements – board members, professors, science writers and journalists – that set the technocultural agenda. Here we’re not talking about some form of ‘techno celebration.’ New media art is not merely a servant to corporate interests. If only it was that simple. The reproach of new media arts ‘celebrating’ technology is a banality, only stated by outsiders; and the interest in life sciences can easily be sold as a (hidden) longing to take part in science’s supra-human ‘triumph of logos,’ but I won’t do that here. Scientists, for their part, are disdainfully looking down at the vaudeville interfaces and well-meant weirdness of biotech art. Not that they will say anything. But the weak smiles on their faces bespeak a cultural gap light years wide. An exquisite non-communication is at hand here. Performance artist Coco Fusco recently wrote a critique of biotech art on the Nettime mailinglist (January 26, 2003). “Biotech artists have claimed that they are redefining art practice and therefore the old rules don't apply to them.” For Fusco bioart’s “heroic stance and imperviousness to criticism sounds a bit hollow and self-serving after a while, especially when the demand for inclusion in mainstream art institutions, art departments in universities, art curricula, art world money and art press is so strong.” From this marginal position, its post-human dreams of transcending the body could better be read as desires to transcend its own marginality, being neither recognized as ‘visual arts’ nor as ‘science.’ Coco Fusco: “I find the attempts by many biotech art endorsers to celebrate their endeavor as if it were just about a scientific or aesthetic pursuit to be disingenuous. Its very rhetoric of transcendence of the human is itself a violent act of erasure, a master discourse that entails the creation of ‘slaves’ as others that must be dominated.” OK, but what if all this remains but a dream, prototypes of human-machine interfaces that, like demo-design, are going nowhere? The isolated social position of the new media arts in this type of criticism is not taken into consideration. Biotech art has to be almighty in order for the Fusco rhetoric to function. Coco Fusco rightly points at artists that “attend meetings with ‘real’ scientists, but in that context they become advisors on how to popularize science, which is hardly what I would call a critical intervention in scientific institutions.” Artists are not ‘better scientists’ and the scientific process is not a better way of making art than any other, Fusco writes. She concludes: “Losing respect for human life is certainly the underbelly of any militaristic adventure, and lies at the root of the racist and classist ideas that have justified the violent use of science for centuries. I don't think there is any reason to believe that suddenly, that kind of science will disappear because some artists find beauty in biotech.” It remains an open question where radical criticism of (life) science has gone and why the new media (arts) canon is still in such a primitive, regressive stage. Links http://www.undesign.org/tiborocity/ Citation reference for this article Substitute your date of access for Dn Month Year etc... MLA Style Lovink, Geert. "Fragments on New Media Arts and Science" M/C: A Journal of Media and Culture< http://www.media-culture.org.au/0308/10-fragments.php>. APA Style Lovink, G. (2003, Aug 26). Fragments on New Media Arts and Science. M/C: A Journal of Media and Culture, 6,< http://www.media-culture.org.au/0308/10-fragments.php>