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1
Liu, Weiqin, Qilu Zou, Yaqiang Zhang, Yong Nie, and Xuemin Song. "Research on Structural Collapse of a Containership under Combined Bending–Torsion by Oblique Waves." Journal of Marine Science and Engineering 12, no. 3 (March 1, 2024): 444. http://dx.doi.org/10.3390/jmse12030444.
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Large waves cause a great number of collapsed-ship accidents, resulting in the loss of many lives and properties. It has been found that most of these collapses are caused by encountering oblique waves. As a result, the ship structure experiences a complex collapse under combined bending and torsion. This paper utilizes a numerical hydroelasto-plastic approach, coupling CFD (Computational Fluid Dynamics) with the nonlinear FEM (Finite-Element Method), to study the structural collapse of a containership in oblique waves. First, a 4600 TEU containership was selected to study its collapse mechanism under oblique waves. Second, a hydroelasto-plastic numerical coupling of CFD and nonlinear FEM is used to co-calculate the wave loads and structural collapse of containership. The hydrodynamic model is constructed and used to solve wave loads in the CFD solver, and a nonlinear FEM model of containership with finer meshes is also modeled to solve the structural collapses, including plasticity and buckling. Third, several oblique-wave cases involving heading angles of 120°, 135°, 150°, and 180° are determined and calculated. Typical cases are discussed for time-domain stress histories and collapsed courses. Finally, the influence of oblique-wave parameters on structural collapse is discussed, and the collapse mechanism of containerships under the action of oblique waves is obtained, which provides a new understanding of ship structure design.
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Kim, Hayong, Moonsu Jo, and Jingul Joo. "Simulation of Dam Collapse Caused by Earthquakes." Journal of the Korean Society of Hazard Mitigation 23, no. 5 (October 31, 2023): 183–89. http://dx.doi.org/10.9798/kosham.2023.23.5.183.
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The occurrence of earthquakes on the Korean Peninsula has been increasing in recent years. However, current emergency action plans for dam and reservoir failures only consider scenarios related to flooding but ignore dam collapses caused by earthquakes. In this study, we simulated dam collapses caused by earthquakes. We focused on the Chungju Dam watershed located in the upper reaches of the Namhan River and analyzed the dam collapse and downstream impacts using the DAMBRK model. We compared the downstream impacts of dam collapse caused by earthquakes with those caused by the PMF. When the dam collapsed because of an earthquake, the estimated peak flood discharge downstream was 44.9%-86.7% of that of the PMF scenario. Similarly, the simulated peak water level downstream when the dam collapsed due to an earthquake was 64.4%-96.9% of that of the PMF scenario. These results indicate that dam collapses caused by seismic events, even in the absence of rainfall, can lead to significant damage downstream. Therefore, future emergency action plans for dams should consider the potential for dam failures caused by earthquakes.
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Mohamadi, Bahaa, Timo Balz, and Ali Younes. "Towards a PS-InSAR Based Prediction Model for Building Collapse: Spatiotemporal Patterns of Vertical Surface Motion in Collapsed Building Areas—Case Study of Alexandria, Egypt." Remote Sensing 12, no. 20 (October 12, 2020): 3307. http://dx.doi.org/10.3390/rs12203307.
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Buildings are vulnerable to collapse incidents. We adopt a workflow to detect unusual vertical surface motions before building collapses based on PS-InSAR time series analysis and spatiotemporal data mining techniques. Sentinel-1 ascending and descending data are integrated to decompose vertical deformation in the city of Alexandria, Egypt. Collapsed building data were collected from official sources, and overlayed on PS-InSAR vertical deformation results. Time series deformation residuals are used to create a space–time cube in the ArcGIS software environment and analyzed by emerging hot spot analysis to extract spatiotemporal patterns for vertical deformation around collapsed buildings. Our results show two spatiotemporal patterns of new cold spot or new hot spot before the incidents in 66 out of 68 collapsed buildings between May 2015 and December 2018. The method was validated in detail on four collapsed buildings between January and May 2019, proving the applicability of this workflow to create a temporal vulnerability map for building collapse monitoring. This study is a step forward to create a PS-InSAR based model for building collapse prediction in the city.
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Zhao, Jinlan, Ke Tong, Junjie Lei, Xiaoliang Bai, Dongfeng Li, Zhaoxi Shen, Tingting Qu, and Xiaolong Li. "Failure Analysis of Tubing Collapse in a Gas Well." Mathematical Problems in Engineering 2023 (December 1, 2023): 1–12. http://dx.doi.org/10.1155/2023/8702719.
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The tubing used in a gas well rarely collapses and fails during applying annulus pressure. In this study, the failure causes of tubing collapse were analyzed by means of data verification, macroscopic observation, magnetic particle inspection, physical and chemical inspection, optical microscopy, and tubing collapse test. Mechanical analysis of the string and full-scale physical simulation test simulating downhole working conditions. Finally, the verification analysis of the collapse test is carried out by the finite element analysis (FEA). The results showed that (1) the physical dimension, physical and chemical properties, and collapse resistance of this batch of tubing met the requirements of the tubing ordering technical standard. (2) Assuming that the well packer slip was unsealed and could slide freely, the mechanical theoretical analysis of collapsed tubing string and collapse test under simulated working condition load was carried out, which reproduced the load when the tubing collapsed. It can be seen from this that the packer did fail. (3) The FEA calculation results showed that when the external pressure was greater than 30.75 MPa, it would inevitably lead to collapse failure in case of packer unsealed. In conclusion, the root cause for the collapse failure of the 105th underground tubing string was that the packer lost its sealing function, resulting in an abnormal axial load. While under the action of external pressure, the tubing was overloaded and collapsed. It is recommended to carry out verification tests on the material performance of packer slip, the dimensional changes of packer tool outer diameter and inner diameter under actual well conditions, the creep behavior of packer seal, and the performance of shear pin under actual working conditions, especially in the well containing H2S, so as to prevent the pressure leakage of gas well annulus caused by packer unsealing and the reoccurrence of such downhole string collapse accidents. The first collapse test under simulated working condition load is conducted in this paper. Analyzing the collapse failure work and putting forward suggestions to effectively prevent similar failures from happening again are of great significance to the oilfield.
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Ashraf, Fahmidah U., and Madeleine M. Flint. "Analysis of Peak Flow Distribution for Bridge Collapse Sites." Water 12, no. 1 (December 21, 2019): 52. http://dx.doi.org/10.3390/w12010052.
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Bridge collapse risk can be evaluated more rigorously if the hydrologic characteristics of bridge collapse sites are demystified, particularly for peak flows. In this study, forty-two bridge collapse sites were analyzed to find any trend in the peak flows. Flood frequency and other statistical analyses were used to derive peak flow distribution parameters, identify trends linked to flood magnitude and flood behavior (how extreme), quantify the return periods of peak flows, and compare different approaches of flood frequency in deriving the return periods. The results indicate that most of the bridge collapse sites exhibit heavy tail distribution and flood magnitudes that are well consistent when regressed over the drainage area. A comparison of different flood frequency analyses reveals that there is no single approach that is best generally for the dataset studied. These results indicate a commonality in flood behavior (outliers are expected, not random; heavy-tail property) for the collapse dataset studied and provides some basis for extending the findings obtained for the 42 collapsed bridges to other sites to assess the risk of future collapses.
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Kremer, Kyle, Claire S. Ye, Sourav Chatterjee, Carl L. Rodriguez, and Frederic A. Rasio. "The Role of “black hole burning” in the evolution of dense star clusters." Proceedings of the International Astronomical Union 14, S351 (May 2019): 357–66. http://dx.doi.org/10.1017/s1743921319007269.
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AbstractAs self-gravitating systems, dense star clusters exhibit a natural diffusion of energy from their innermost to outermost regions, leading to a slow and steady contraction of the core until it ultimately collapses under gravity. However, in spite of the natural tendency toward “core collapse,” the globular clusters (GCs) in the Milky Way exhibit a well-observed bimodal distribution in core radii separating the core-collapsed and non-core-collapsed clusters. This suggests an internal energy source is at work, delaying the onset of core collapse in many clusters. Over the past decade, a large amount of work has suggested that stellar black holes (BHs) play a dynamically-significant role in clusters throughout their entire lifetimes. Here we review our latest understanding of BH populations in GCs and demonstrate that, through their dynamical interaction with their host cluster, BHs can naturally explain the distinction between core-collapsed and non-core-collapsed clusters through a process we call “black hole burning.”
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Marsudi, Dianita Ratna Kusumastuti, Nursetiaji Pamungkas, Dedi Budi Setiawan, Primasiwi Harprastanti, and Marton. "Study of Structural Analysis of Damaged Concrete Beams Strenghted with Carbon Fiber Reinforced Polymer." International Journal of Advances in Scientific Research and Engineering 08, no. 04 (2022): 29–39. http://dx.doi.org/10.31695/ijasre.2022.8.4.4.
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It is necessary to repair the cracks in the concrete structure to prevent further damage that can lead to the collapse of the structure. Repairs can restore and increase the strength of structural elements so that they are able to withstand the load in accordance with the design load, finally further decisions can be made for the next function. The results of the flexural strength test of K-150 collapsed concrete beams 100% able to withstand a load of 58 kN, K-250 collapsed 100% able to withstand a load of 64.33 kN, K-150 coated with CRFP tensile part collapsed 100% able to withstand a load of 82 kN, K -250 is coated with CRFP, the tensile part collapses 100% able to withstand a load of 91.67 kN, the quality of K-250 collapses 60% is able to withstand a load of 39.17 kN. K-250 strength concrete beam collapsed 60% maximum CRFP repair able to withstand a load of 87.67 kN. For testing of concrete beams with f'c quality of 20.71 MPa, 100% collapse with a maximum average of 29.00 MPa. The flexural strength of the concrete beam with f'c quality is 20.71 MPa, 60% collapse with an average load of 19.00 MPa. For the flexural strength of the f'c 20.71 MPa concrete beam, improvements were made to be able to withstand an average load of 52.86 MPa. Analysis of the test results by increasing the area and CRFP can increase the bearing capacity of concrete blocks. If in a construction work there is a doubt from the user about the portal being built, then CRFP can increase its flexural strength.
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Lei, B., W. Ding, X. Huang, and Q. Zhang. "Analysis of tunnel collapse disasters during operation and exploration of disaster damage mechanisms." IOP Conference Series: Earth and Environmental Science 1333, no. 1 (May 1, 2024): 012049. http://dx.doi.org/10.1088/1755-1315/1333/1/012049.
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Abstract Highway tunnel collapse during the operation period is a serious threat to the stability of tunnel operation. Thus, it is important to investigate the disaster-causing mechanism to prevent the occurrence of disasters. In this paper, based on 155 cases of domestic and foreign highway tunnel collapses during operation, we statistically analyze the causes of the collapses and the year of occurrence, and we explore the disaster-causing mechanism of tunnel collapses through numerical simulation. Tunnel collapses in operation period are affected by geological factors, lining factors, and accidental factors. The primary causes of tunnel collapses are determined to be the post-lining cavity, lining crack expansion, and fire. A single factor cannot lead to tunnel collapse, and the probability of collapse increases under the coupling of multiple factors. Through a numerical simulation method, the evolution mechanism of tunnel collapse caused by the post-lining cavity is analyzed, which lays the foundation for establishing the tunnel collapse prediction model and qualitative risk assessment system of highway tunnel collapse.
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Laffin, Matthew K., Charles S. Zender, Melchior van Wessem, and Sebastián Marinsek. "The role of föhn winds in eastern Antarctic Peninsula rapid ice shelf collapse." Cryosphere 16, no. 4 (April 13, 2022): 1369–81. http://dx.doi.org/10.5194/tc-16-1369-2022.
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Abstract. Ice shelf collapse reduces buttressing and enables grounded glaciers to contribute more rapidly to sea-level rise in a warming climate. The abrupt collapses of the Larsen A (1995) and B (2002) ice shelves on the Antarctic Peninsula (AP) occurred, at least for Larsen B, when long-period ocean swells damaged the calving front and the ice shelf was inundated with melt lakes that led to large-scale hydrofracture cascades. During collapse, field and satellite observations indicate föhn winds were present on both ice shelves. Here we use a regional climate model and machine learning analyses to evaluate the contributory roles of föhn winds and associated melt events prior to and during the collapses for ice shelves on the AP. Föhn winds caused about 25 % ± 3 % of the total annual melt in just 9 d on Larsen A prior to and during collapse and were present during the Larsen B collapse, which helped form extensive melt lakes. At the same time, the off-coast wind direction created by föhn winds helped melt and physically push sea ice away from the ice shelf calving fronts that allowed long-period ocean swells to reach and damage the front, which has been theorized to have ultimately triggered collapse. Collapsed ice shelves experienced enhanced surface melt driven by föhn winds over a large spatial extent and near the calving front, whereas SCAR inlet and the Larsen C ice shelves are affected less by föhn-wind-induced melt and do not experience large-scale melt ponds. These results suggest SCAR inlet and the Larsen C ice shelves may be less likely to experience rapid collapse due to föhn-driven melt so long as surface temperatures and föhn occurrence remain within historical bounds.
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Yang, Xiaoning, Brian W. Stump, and W. Scott Phillips. "Source mechanism of an explosively induced mine collapse." Bulletin of the Seismological Society of America 88, no. 3 (June 1, 1998): 843–54. http://dx.doi.org/10.1785/bssa0880030843.
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Abstract Mining explosions and collapses, in addition to earthquakes, may trigger the future Comprehensive Test Ban Treaty (CTBT) monitoring system. Many shallow, spontaneously occurring mine collapses have implosional source mechanisms that might provide a physical basis to discriminate them from explosions. In this study, an explosively induced mine collapse was investigated. The collapse occurred immediately after the support pillars of a 320-m-deep underground mine opening were destroyed by explosives. It had an Lg body-wave magnitude (mbLg) of 2.8. We analyzed free-surface ground-motion data (within 1200 m) from the collapse by waveform forward modeling and time-dependent source moment-tensor inversion. The results indicate that the source mechanism of the collapse can be represented by a horizontal opening and closing crack. The time functions of the diagonal source moment-tensor components are similar to that of a spall source accompanying an underground explosion. A unique source characteristic of the induced collapse is that, unlike spontaneous collapses, the induced collapse initiated as a tensile crack. Because of the initially expansive source characteristic, this kind of induced mine collapses may pose some difficulties to the seismic discrimination problem. Despite the similarities between the induced mine collapse and underground explosions, the collapse has a more band-limited source spectrum and seems to be more efficient in shear and surface-wave generation.
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Lobkina, Valentina. "Analysis of Roof Collapse Cases Caused by Snow Loads in Russia (2001–2021)." Sustainability 13, no. 24 (December 8, 2021): 13580. http://dx.doi.org/10.3390/su132413580.
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Cases of building decay and structural damage caused by the impact of snow loads are registered every year throughout the world. Such destruction not only results in property loss, but also leads to human losses. A database on 266 cases of roof collapse caused by snow loads in Russia for the period from 2001 to 2021 was collated for this study. The data were analyzed by date and place of collapse, building data, and number of victims. The analysis showed that civilian buildings are the most vulnerable, comprising 78% of the total number of collapses, followed by industrial buildings with 15% and agricultural buildings with only 7%. The relationships between roof shape, roofing material, number of floors, and type of collapsed building were determined. The data processing results showed that low-rise residential buildings (one to two floors) with a gable roof covered with fiber cement should be considered the most vulnerable. A linear relationship was revealed between a collapse area of more than 150 m2 and the cumulative number of collapse cases. The obtained results have practical application for rating building vulnerability to natural hazards and assessing the risk of emergencies associated with snow loads.
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Yang, Tengtian. "Investigation on Disaster Mechanism of Diversion Tunnel Induced by Gripper TBM in Hydrokarst Erosion Stratum and Engineering Measures." Buildings 14, no. 3 (February 27, 2024): 625. http://dx.doi.org/10.3390/buildings14030625.
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In gripper tunnel boring machine (TBM) tunneling through complex geological formations, the safe and efficient recovery from large-scale collapses remains a formidable challenge. In this study, we investigate the causes of a 1246 m3 collapse that occurred during the gripper TBM tunneling in the diversion tunnel in Xinjiang, China. Various techniques including TSP seismic waves, CFC advanced water exploration, laboratory point load tests and packer permeability tests were employed for thorough research. The examination discloses that the water softening in biotite-quartz schist in fractured zones contributes significantly to the loosening and dislocation of rock layers along joints. The gripper TBM’s cutterhead exacerbates this process through cutting action and vibrations, causing large-scale instability and eventual rock mass collapse. To tackle this engineering problem, we propose a three-step treatment scheme comprising “Reinforcement-Backfill-Re-excavation”. Furthermore, we propose a technique to handle TBM collapses by creating a “protective shell” within the cavity. The safety and feasibility of these proposed solutions were thoroughly validated through numerical simulations. Also, we utilized the Hoek-Brown theory and Rostami prediction formula to establish recommended values for the total thrust and total torque of the TBM during the collapsed section. The proposed treatment scheme and estimated parameters were successfully applied, resulting in a comprehensive solution from collapse handling to tunneling. This study offers valuable details on effectively managing large-scale collapses in gripper TBM tunneling, which can be useful for similar tunnel engineering and improve safety and efficiency.
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Luo, Jing, Weilin Xu, Jun Deng, Yanwei Zhai, and Qi Zhang. "Experimental Study on the Impact Characteristics of Cavitation Bubble Collapse on a Wall." Water 10, no. 9 (September 15, 2018): 1262. http://dx.doi.org/10.3390/w10091262.
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As a hydrodynamic phenomenon, cavitation is a main concern in many industries such as water conservancy, the chemical industry and medical care. There are many studies on the generation, development and collapse of cavitation bubbles, but there are few studies on the variation of the cyclic impact strength on walls from the collapse of cavitation bubbles. In this paper, a high-speed dynamic acquisition and analysis system and a pressure measuring system are combined to study the impact of a cavitation bubble generated near a wall for various distances between the cavitation bubble and the wall. The results show that (1) with the discriminating criteria of the impact pressure borne by the wall, the critical conditions for the generation of a micro-jet in the collapse process of the cavitation bubbles are obtained, and therefore collapses of cavitation bubbles near the wall are mainly divided into primary impact area collapses, secondary impact area collapses and slow release area collapses; (2) it can be seen from the impact strength of the cavitation bubble collapse on the wall surface that the impact of cavitation bubbles on the wall surface during the first collapse decreases as γ (the dimensionless distance between the cavitation bubble and the wall) increases, but the impact of the second collapse on the wall surface increases first and then decreases sharply. When γ is less than 1.33, the impact on the wall surface is mainly from the first collapse. When γ is between 1.33 and 2.37, the impact on the wall surface is mainly from the second collapse. These conclusions have potential theoretical value for the utilization or prevention and control technologies for cavitation erosion.
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Siddiq, Jibril Abubakar, and Professor Li Xianyi. "Challenges under Collapse of Building in Nigeria and Way to Improve It." International Journal for Research in Applied Science and Engineering Technology 10, no. 5 (May 31, 2022): 213–19. http://dx.doi.org/10.22214/ijraset.2022.42021.
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Abstract: Building collapse in Nigeria is alarming and indeed has become a subject of great concern. For the past 10 years an overwhelming number of buildings have collapsed in Nigerian rural and urban cities, with about 77% rise from the previous decade. The incidence of building failures and collapses has become major issues of concern in the development of Nigeria as the losses in terms of lives and properties are now becoming very alarming. This study provides critical reasoning and contributions regarding structural failures observed in Nigeria. To address this problem, The study aimed at exploring major causes of building collapse in Nigeria with a view of establishing effective way of solving the problem. The primary data that will be used if from the Questionnaires and field observations while secondary data will be obtained from textbooks, newspapers and Journal articles . This significant of this paper is to use building information modeling BIM to improve full project visualization, reduced construction collapse, cost, increased productivity, safer construction, better building and information analysis. Keywords: Building Information Modelling, construction, industry, management project.
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Thorson, James T., Trevor A. Branch, and Olaf P. Jensen. "Using model-based inference to evaluate global fisheries status from landings, location, and life history data." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 4 (April 2012): 645–55. http://dx.doi.org/10.1139/f2012-016.
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Assessing fishery collapses worldwide is hindered by the lack of biomass data for most stocks, leading to the use of landings-based proxies or the assumption that existing stock assessments are globally representative. We argue that the use of sparse assessments to evaluate fishery status requires model-based inference because assessment availability varies spatially and temporally, and we derive a model that extrapolates from assessment results to available landings, life history, and location data. This model uses logistic regression to classify stocks into different prediction bins and estimates the probability of collapse in each using cross-validation. Results show that landings, life history, and location are informative to discriminate among different probabilities of collapse. We find little evidence that regions with fewer assessments have a greater proportion of collapsed stocks, while acknowledging weak inferential support regarding regions with one or fewer assessments. Our extrapolation suggests that 4.5%–6.5% of stocks defined by landings data are collapsed, but that this proportion is increasing. Finally, we propose a research agenda that combines stock assessment and landings databases while overcoming limitations in each.
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Makoond, Nirvan, Andri Setiawan, Manuel Buitrago, and Jose M. Adam. "Arresting failure propagation in buildings through collapse isolation." Nature 629, no. 8012 (May 15, 2024): 592–96. http://dx.doi.org/10.1038/s41586-024-07268-5.
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AbstractSeveral catastrophic building collapses1–5 occur because of the propagation of local-initial failures6,7. Current design methods attempt to completely prevent collapse after initial failures by improving connectivity between building components. These measures ensure that the loads supported by the failed components are redistributed to the rest of the structural system8,9. However, increased connectivity can contribute to collapsing elements pulling down parts of a building that would otherwise be unaffected10. This risk is particularly important when large initial failures occur, as tends to be the case in the most disastrous collapses6. Here we present an original design approach to arrest collapse propagation after major initial failures. When a collapse initiates, the approach ensures that specific elements fail before the failure of the most critical components for global stability. The structural system thus separates into different parts and isolates collapse when its propagation would otherwise be inevitable. The effectiveness of the approach is proved through unique experimental tests on a purposely built full-scale building. We also demonstrate that large initial failures would lead to total collapse of the test building if increased connectivity was implemented as recommended by present guidelines. Our proposed approach enables incorporating a last line of defence for more resilient buildings.
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Sciorio, Romualdo, Raquel Herrer Saura, K. Joo Thong, Marga Esbert Algam, Susan Jane Pickering, and Marcos Meseguer. "Blastocyst collapse as an embryo marker of low implantation potential: a time-lapse multicentre study." Zygote 28, no. 2 (January 13, 2020): 139–47. http://dx.doi.org/10.1017/s0967199419000819.
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SummarySpontaneous blastocyst collapse during in vitro embryo development has been suggested as a novel marker of embryo quality. Therefore, the aim of this multicentre study was to carry out a retrospective multicentre analysis to investigate the correlation between blastocyst collapse and pregnancy outcome. Here, 1297 intracytoplasmic sperm injection (ICSI)/in vitro fertilization (IVF) fresh cycles, with an elective single blastocyst transfer (eSET) were included in this study. Embryos were cultured individually in 6.0% CO2, 5.0% O2, 89.0% N2, using single step medium (GTLTM VitroLife, Sweden) or sequential medium (CookTM, Cook Medical, Australia) and selected for transfer using standard morphological criteria. With the use of time-lapse monitoring (TLM), blastocysts were analyzed by measuring the maximum volume reduction and defined as having collapsed, if there was ≥ 50% volume reduction from the expanded blastocyst and the collapse event. Following embryo replacement, each blastocyst was retrospectively allocated to one of two groups (collapsed or not collapsed). Here, 259 blastocysts collapsed once or more during development (19.9%) and the remaining 1038 either contracted minimally or not collapsed (80.1%). A significantly higher ongoing pregnancy rate (OPR) of 51.9% (95% CI 48.9–59.9%) was observed when blastocysts that had not collapsed were replaced compared with cycles in which collapsed blastocysts were transferred 37.5% (95% CI 31.6–43.4%). This study suggests that human blastocysts that collapse spontaneously during development are less likely to implant and generate a pregnancy compared with embryos that do not. Although this is a retrospective study, the results demonstrated the utility of collapse episodes as new marker of embryo selection following eSET at blastocyst stage.
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Tan, Fei, Wufeiyu Tan, Feifei Yan, Xin Qi, Qinghua Li, and Zhikai Hong. "Model Test Analysis of Subsurface Cavity and Ground Collapse Due to Broken Pipe Leakage." Applied Sciences 12, no. 24 (December 19, 2022): 13017. http://dx.doi.org/10.3390/app122413017.
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Urban ground collapse is a common geological disaster characterized by its invisible nature, particularly in China, and results in significant socioeconomic losses and even loss of life. Underground pipeline breakage is the most common factor leading to urban ground collapses. Hence, it is essential to study how different types of pipeline breakages initiate the collapse mechanism. In this study, an indoor model test was conducted to directly observe the process of collapse due to broken pipe leakage. A broken pipe was put into a model box and tested by an experimental device. The results showed that among the different pipeline breakage types, vertical damage had the greatest influence on the degree of cavity development and ground collapse. Similarities were observed in the patterns of cavity evolution development and the extent of ground collapse as well, further revealing the significance of the cavity evolution process in predicting ground collapses.
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Yong, Kang. "Mechanical Test on Pipe Collapse under External Pressure." Advanced Materials Research 291-294 (July 2011): 1255–58. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.1255.
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Many factors result in pipe collapses under certain external pressure. The relations among them have been studied by the pipe collapse tests. This pepper focused on the test analyses of steel pipe collapse resistance. Those include a pipe collapse pressure test under external pressure and illustrate both test and preparing theoretical analysis, and results of the collapse pressure with the effects on the tendency of ovality. In addition to various pipe collapse data and mechanical test methods, this study will offer a summary of the findings for the further intention of theories researches.
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Wang, Yan, Yong Jun Liu, and Tai Bin Wang. "A Summary Review of Progressive Collapse of Reinforced Concrete Frame Structure under Fire." Advanced Materials Research 1065-1069 (December 2014): 2315–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.2315.
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In recent years, many progressive collapse accidents have occurred at home and abroad, due to the progressive collapses of a structure that often disproportion between initial damages and large collapses, these accidents caused significant casualties and serious economic losses. This paper first analyzes the research background and the definition of progressive collapse, then contrasts China with Britain, the United States, Europe and other countries for theory research status, specification research status, engineering and simulation research status, prevention measures of progressive collapse. Compared with other countries I have found that if our country introduced a comprehensive related design specifications, some progressive collapse accidents can be avoided or ease. So there will be plenty of work to be done in our country.
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KOLESÁROVÁ, ANNA. "COLLAPSED INPUT-BASED AGGREGATION." International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 09, no. 02 (April 2001): 217–28. http://dx.doi.org/10.1142/s0218488501000752.
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Collapsed input-based aggregation leading to constrained aggregation operators is discussed. Constrained aggregation operators eliminating a non–distinguishing evaluation are studied. Moreover, collapse invariant aggregation operators are defined and a complete characterization of symmetric collapse invariant aggregation operators, which are independent of the position of the collapsed input, is given. Several examples are included.
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Galvis, Francisco A., Eduardo Miranda, Pablo Heresi, Héctor Dávalos, and Jorge Ruiz-García. "Overview of collapsed buildings in Mexico City after the 19 September 2017 (Mw7.1) earthquake." Earthquake Spectra 36, no. 2_suppl (July 30, 2020): 83–109. http://dx.doi.org/10.1177/8755293020936694.
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An intraslab normal-faulting earthquake struck the central region of Mexico on 19 September 2017, leading to the collapse of 44 buildings in Mexico City. After the earthquake, the authors collected information in situ and through social media about the collapsed buildings, which was statistically processed to identify the causes of their collapse. This article presents the main collapse statistics, which revealed that 64% of the collapsed buildings had between 1 and 5 stories, 61% had a seismic-force-resisting system based on reinforced concrete columns with flat slabs, 57% experienced a soft-story mechanism, 91% were built before 1985, 43% were located at the corner blocks, and 10% exhibited pounding with neighboring buildings. The spatial distribution of the collapsed buildings and the recorded ground motion features suggest that short- and medium-period buildings having well-known vulnerabilities were particularly prone to collapse under amplified high-frequency seismic waves typical of intraslab normal-faulting earthquakes, such as the 2017 Puebla–Morelos earthquake.
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Chen, Huanxia, Junqi Fan, and Jingmao Xu. "Analysis and Experimental Study on the Stability of Large-Span Caverns’ Surrounding Rock Based on the Progressive Collapse Mechanism." Applied Sciences 14, no. 13 (July 7, 2024): 5929. http://dx.doi.org/10.3390/app14135929.
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The collapse failure of rock surrounding caverns involves a progressive collapse process. Based on the nonlinear Hoek–Brown failure criterion and the upper limit theorem, the whole process curve of the progressive collapse of the surrounding rock of a large-span cavern is outlined in this paper. The progressive collapse process of the surrounding rock of the large-span cavern is experimentally studied using an independently developed visualized large-span-cavern geomechanical model test device with variable angles. The results show that, through theoretical calculation and model tests, the surrounding rock at the top of the large-span cavern undergoes three collapses. Under the condition of rock mass and the shape of the cavern, the larger the span of the cavern, the more times the surrounding rock collapses; with the increase in surrounding rock pressure, the first collapse occurs in the middle part of the arch roof. When the overlying load reaches a certain level, the arch foot becomes the weakest part, and the rock undergoes shear failure along the arch foot, gradually extending upwards, accompanied by multiple collapses, forming a progressive collapse process. The theoretical calculation results of this paper are basically consistent with the scope of the model test, and the research results can provide a basis for the construction and support design of the large-span cavern.
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Anosike, Nwabueze Michael. "VIEWS OF CONSTRUCTION PROFESSIONALS’ ON THE CAUSES AND REMEDIES OF BUILDING COLLAPSE IN NIGERIA." International Journal of Engineering Technologies and Management Research 8, no. 6 (July 6, 2021): 68–85. http://dx.doi.org/10.29121/ijetmr.v8.i6.2021.976.
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The collapse of building has been an issue of great concern to all and sundry in Nigeria and yet these buildings are major contributors to the development of any nation. Therefore, when a building collapses, it fails to render the functions which it should perform to the people and the government. A building is regarded as collapsed if the whole structure or part thereof has fallen down and therefore cannot serve the purpose for which it was intended. When building collapses, it generates deep emotional reactions from every segment of the population constituting great losses to the country in terms of physical, human and material resources. Therefore, the aim of this research is to assess the opinion of construction professionals who are perceived as critical stakeholders on the causes as well as to proffer remedies to curb the menace. The case study is Owerri municipal council, Imo State, Nigeria. A well-structured four-point Scale questionnaire was drawn and administered to 250 selected sampled respondents to elicit data. Out of that the 250 respondents, 193 representing 77% valid respondents were retrieved and utilized in the study analysis. The analysis revealed that all critical construction stakeholders were implicated as contributors towards the incidences of building collapse. The study recommends among others that, Government, professionals’ as well as other critical stakeholders should adhere strictly to their statutory roles in order to curb the menace of building collapse in Nigeria.
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Wang, Hui Min, and Hua Jun Guo. "Collapse Cause Analysis and Treatment Research of West Slope Tunnel." Applied Mechanics and Materials 470 (December 2013): 954–57. http://dx.doi.org/10.4028/www.scientific.net/amm.470.954.
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Abstract: West Slope Tunnel's surrounding rock is broken. A positive step method is used in the reconstruction process of collapsed West Slope Tunnel. During tunnel construction process, heavy rain cause a landslide failure of tunnel (Located in DK51+175- DK51+195). The mainly collapsed area is located in the position of DK51+180. According to collapsing, we executed the settlement observation, cross-section deformation detection and upper crack observation.When collapse settlement is basically stable, the collapse is segmented to settle. The previous board of Secondary lining for the collapse need to add steel reinforcement and tunnel collapse cavity backfill C30 concrete. When concrete strength is expected ,it need to be excavated and must keep the core soil. The advanced small pipe is needed to stabilize the soil before the excavation section. In invasion of secondary lining collapse, girdle previous Primary Support and reform Primary Support.. Add I16 steel frame where necessary. We must strengthen the tunnel monitoring to ensure the safety during tunnel construction process.
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Cheng, X. S., G. Zheng, Y. Diao, T. M. Huang, C. H. Deng, D. Q. Nie, and Y. W. Lei. "Experimental study of the progressive collapse mechanism of excavations retained by cantilever piles." Canadian Geotechnical Journal 54, no. 4 (April 2017): 574–87. http://dx.doi.org/10.1139/cgj-2016-0284.
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An increasing number of catastrophic progressive collapses of deep excavations have occurred throughout the world. However, the research on progressive collapse mechanisms is limited. In this paper, two categories of model tests were conducted to investigate the mechanism of partial collapse (sudden failures of certain retaining piles) and progressive collapse. The model test results show that partial collapse can cause a sudden increase in the bending moments of adjacent piles via an arching effect. The load-transfer coefficients are defined to be equal to the peak increase ratios of the maximum bending moments in adjacent piles (peak moments caused by collapse over the values before the collapse). When the maximum load-transfer coefficient is larger than the bearing capacity safety factor of the piles, the partial failure will lead to progressive collapse. The influential factors of the progressive collapse mechanism, such as the partial collapse extent, excavation depth, and capping beam, were also investigated. During progressive collapse, the previous failed pile could cause new stress arching; simultaneously, the soil behind certain nearest intact piles could become loosened and destroy the arch springing of the stress arching, causing the progressive collapse to cease gradually.
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Yao, Chuangchuang, Lingjing Li, Xin Yao, Renjiang Li, Kaiyu Ren, Shu Jiang, Ximing Chen, and Li Ma. "Study on the Identification, Failure Mode, and Spatial Distribution of Bank Collapses after the Initial Impoundment in the Head Section of Baihetan Reservoir in Jinsha River, China." Remote Sensing 16, no. 12 (June 20, 2024): 2253. http://dx.doi.org/10.3390/rs16122253.
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After the initial impoundment of the Baihetan Reservoir in April 2021, the water level in front of the dam rose about 200 m. The mechanical properties and effects of the bank slopes in the reservoir area changed significantly, resulting in many bank collapses. This study systematically analyzed the bank slope of the head section of the reservoir, spanning 30 km from the dam to Baihetan Bridge, through a comprehensive investigation conducted after the initial impoundment. The analysis utilized UAV flights and ground surveys to interpret the bank slope’s distribution characteristics and failure patterns. A total of 276 bank collapses were recorded, with a geohazard development density of 4.6/km. The slope gradient of 26% of the collapsed banks experienced an increase ranging from 5 to 20° after impoundment, whereas the remaining sites’ inclines remained unchanged. According to the combination of lithology and movement mode, the bank failure mode is divided into six types, which are the surface erosion type, surface collapse type, surface slide type, bedding slip type of clastic rock, toppling type of clastic rock, and cavity corrosion type of carbonate rock. It was found that the collapsed banks in the reservoir area of 85% developed in the reactivation of old landslide deposits, while 15% in the clastic and carbonate rock. This study offers guidance for the next phase of bank collapse regulations and future geohazards prevention strategies in the Baihetan Reservoir area.
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Liu, Chien. "A theory of norm collapse." Rationality and Society 32, no. 2 (May 2020): 119–43. http://dx.doi.org/10.1177/1043463120921255.
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How a social norm emerges has been studied extensively. However, how a norm collapses has rarely been addressed in the literature. In this article, extending the theories of norm emergence by Coleman and Axelrod, I propose a theory of norm collapse. This theory specifies one micro mechanism and macro–micro–macro process through which a norm likely decays and eventually collapses. Then, as a test, I use computer simulation to simulate the process of the norm emergence and collapse. The result of the computer simulation demonstrates that the proposed theory has internal logical consistency. Finally, I conclude by discussing some implication of this research.
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Luo, Tian. "Analysis of Seismic Collapse-Resistant Influencing Factors of RC Frame Structure." Highlights in Science, Engineering and Technology 51 (May 16, 2023): 50–56. http://dx.doi.org/10.54097/hset.v51i.8237.
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The RC frame structure is widely applied in China due to its flexible layout and good anti-collapse capacity during an earthquake. However, a lot of RC frame structures collapsed in the strong earthquake zone during the Wenchuan earthquake. The collapse resistance of the RC frame structures during an actual earthquake is inconsistent to the designed seismic collapse resistance in a project. So the collapse resistance of reinforced concrete (RC) frame structures during an earthquake and its influencing factors are a hot research topic in the field of earthquake engineering. Based on the research results of scholars in recent years, this paper briefly discusses the evaluation criteria of structural collapse, the structural collapse mechanism during a real earthquake and the influence of nonstructural components. Finally, the influencing factors are summarized in terms of design methods, plastic hinges and nonstructural members, which have certain reference significance for the seismic collapse resistance design.
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Moede, John D. "Medical Aspects of Urban Heavy Rescue." Prehospital and Disaster Medicine 6, no. 3 (September 1991): 341–48. http://dx.doi.org/10.1017/s1049023x00038784.
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The concept of Urban Heavy Rescue is gaining increasing recognition within the emergency response community. Urban Heavy Rescue has come to denote the unique demands for special equipment and personnel as the result of structural collapse. Recent earthquakes in California, the Philippines, and Soviet Armenia as well as the building collapses in Brownsville, Texas, and New York City provided excellent demonstrations of the concept of specialized structural collapse teams. These events even have prompted the Federal Emergency Management Agency (FEMA) to establish a National Urban Search and Rescue System of special task forces trained in victim location and extrication from collapsed structures. This system will comprise an immediate federal response mechanism for assisting first responders in such activities. The National Search and Rescue System was based on post-event evaluations that pointed out a need not only for more applicable equipment and trained personnel, but also for the timely placement of the these resources.
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Ma, Xuetong, Qipeng Li, Hao Zhang, Debin Gao, Jiao Long, and Zhengzheng Li. "Prediction of Reservoir Bank Collapse Based on the Limit Equilibrium Theory." Advances in Civil Engineering 2023 (June 13, 2023): 1–9. http://dx.doi.org/10.1155/2023/9050873.
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The prediction of reservoir bank collapse width is a unique problem encountered in the construction of hydropower projects. Existing empirical graphic methods are based on the final state of bank collapse and can be used to predict only bank collapse width, and they thus do not adequately reflect the characteristics of the bank collapse process. To solve this problem, a prediction model for bank collapse width based on the limit equilibrium theory was established, and the key parameters and bank collapse process of the model were analyzed. The results reveal the necessity of selecting a reasonable underwater accumulation rate when predicting the bank collapse width using the limit equilibrium theory. At a constant ratio of water depth to bank slope height, the underwater accumulation rate increases with increasing bank slope height, with a linear relationship between them. In contrast, the bank slope angle has little impact on bank collapse width. Specifically, it mainly affects the width of the first bank collapse but has little effect on the width of subsequent bank collapses. With an increase in the bank slope angle, the bank collapse width fluctuates and rises. The prediction model of bank collapse width based on the limit equilibrium theory can better explain the time-dependent behavior of bank collapse. The research results are of high significance for the prediction of loess bank collapse.
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Reznik, Petro, Mohamd Almohamad, and Vladyslav Tenesesku. "ANALYSIS OF CONSTRUCTIVE SOLUTIONS OF THE EXISTING BUILDINGS OF THE HOUSING FUND OF THE KHARKIV CITY ON THE SUBJECT OF THEIR PERFORMANCE AS A CONSEQUENCE OF THE INFLUENCE OF COMBAT ACTIONS." Collection of Scientific Works of the Ukrainian State University of Railway Transport, no. 201 (September 30, 2022): 41–56. http://dx.doi.org/10.18664/1994-7852.201.2022.267755.
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The article examines the main structural solutions of existing residential buildings inthe city of Kharkiv and analyzes their working capacity from the point of view of resistance toexplosive effects and, as a result, progressive collapse. It is known that progressive collapse ischaracteristic of extreme (emergency) cases, when due to destruction of a responsible element of thestructure as a result of a gas explosion, ammunition bursts, climatic cataclysms, transport collapses,etc a part of the building or the entire structure collapses. It is noted that every year, the interest ofthe world scientific community in the issues of progressive collapse is growing, because,unfortunately, the number of cases of avalanche-like collapse of buildings of various types isincreasing. This was facilitated by already known cases of collapses of various objects, such as theRonan Point residential building (Great Britain) in 1968 or the buildings of the World Trade Center(USA) in 2011, or the very recent case of the collapse of a residential building in Surfside (USA) in2021. At the same time, it is noted that domestic regulations do not yet specify the methodology forcalculating buildings before progressive collapse, and the existing methods of experimental andnumerical analysis still need to be refined. Unfortunately, the list of such objects is increasing, andtoday, Ukraine has added to it numerous destroyed buildings as a result of ongoing hostilities on itsterritory. Therefore, for our country in the current conditions, the issue of ensuring the future stability of all buildings, and in particular, the housing stock against progressive collapse, is an urgent issue.On the basis of the analysis of the constructive solutions of the housing development in the city ofKharkiv, the type of buildings that, according to the authors of the article, has the greatest resource,is singled out, and brief recommendations are given for its increase in the future.
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Scott Phillips, W., D. Criag Pearson, Xiaoning Yang, and Brian W. Stump. "Aftershocks of an explosively induced mine collapse at White Pine, Michigan." Bulletin of the Seismological Society of America 89, no. 6 (December 1, 1999): 1575–90. http://dx.doi.org/10.1785/bssa0890061575.
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Abstract We recorded an explosively induced, 320-m-deep mine collapse and subsequent aftershocks at White Pine, Michigan, using an array of 12 seismic stations, sited within 1 km of surface ground zero. The collapse, which followed the rubblizing of a 2 × 104 m2 panel of a room-and-pillar copper mine, was induced to facilitate leaching operations. The explosions produced little seismic energy; however, fracturing and collapse stages produced large signals that were observed at distances up to 900 km, yielding a magnitude (mbLg) of 2.8. Previous work showed the initial collapse to be an expanding seismic source, interpreted as an opening tensile crack, opposite to the implosional character most often observed for natural mine collapses (Yang et al., 1998). We counted over 4000 aftershocks; their occurrence rate followed the modified Omori law: rate = 560 (time − 0.01)−1.3, with time in hours. Based on P-wave polarities, we identified events of shear-slip, implosional, and tensile character in the aftershock sequence. For shear-slip events, we found stress drops of 1 bar or less, seismic moments of 1015−1017 dyne cm, (Mw−0.8−0.5) and source radii of 10-50 m. Corner frequencies for implosional events were relatively low, an indication that the collapsed cavity played a role in the source process. This caused implosional events to separate from other events in source parameter plots, providing a technique for classifying events of unknown type. We obtained locations of 135 aftershocks using P- and S-wave data. The aftershock zone was less than 100-m thick, situated just above and along the western, mined edge of the collapsed mine panel. Implosional events occurred at the bottom of the active volume, while shear-slip events were distributed throughout. Shear-slip focal mechanisms indicated thrusting along north-striking planes, consistent with the high, eastwest regional compressive stress, coupled with a local decrease in vertical stress. The inferred deficit of vertical stress above the western panel edge following collapse indicated that overburden load shifted preferentially to the surrounding, unmined areas, consistent with lower-than-predicted stresses measured in the first row of intact pillars.
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Reznik, Рetro, Sergiy Grebenchuk, Roman Koreniev, and Vitaliy Bondarenko. "Research of the specific steel shells progressive collapse prevention." ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 1, no. 52 (July 5, 2019): 58–64. http://dx.doi.org/10.26906/znp.2019.52.1676.
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The article deals with coatings in the form of the specific steel shells. After a detailed analysis certain number of accidentsand collapses, these collapses can be classified as “progressive” collapse. The main purpose of the article is the developmentof design algorithms for evaluation of the stress-strain state and preventing the progressive collapse of the specific steelshells. The method of prevention progressive collapse has been developed in the form of a constructive modernization.The comparative finite-element analysis of the strained-strain state of the specific shells original models, models of discretecontinualribbed shells (with constructive upgrading) and models of solid ribbed shells has been carried out. From the analysisresults it can be concluded that the proposed modernization method can be considered as one of the possible options forpreventing progressive collapses and increasing the bearing capacity of specific steel shells.
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Wang, Yi Xuan, and Lei Huang. "Research on Numerical Model for Earthquake Induced Progressive Collapse of High-Rise Buildings." Applied Mechanics and Materials 716-717 (December 2014): 223–26. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.223.
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Progressive collapse is defined as the collapse of the whole building due to local weak stories or weak zones. In this paper, collapse should theoretically be avoided for any building under any earthquake, it is necessary to study the collapse behavior of buildings to acquire a better understanding of the collapse mechanism and to find efficient methods to prevent it. The collapse process highly depends on the feature of the whole structural system, so numerical simulation becomes a major method to study it. Based on the finite element method, by selecting the appropriate cell death and cell contact algorithm criterion can better simulate the structure collapsed in an earthquake under the continuity of the whole process of destruction, to help understand the causes and mechanism of structural damage. The real buildings are analyzed to study the failure mechanism of the structure. The models proposed are reasonable to study the seismic collapse mechanism of high-rise buildings.
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Halevi, Goni, Belinda Wu, Philipp Mösta, Ore Gottlieb, Alexander Tchekhovskoy, and David R. Aguilera-Dena. "Density Profiles of Collapsed Rotating Massive Stars Favor Long Gamma-Ray Bursts." Astrophysical Journal Letters 944, no. 2 (February 1, 2023): L38. http://dx.doi.org/10.3847/2041-8213/acb702.
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Abstract Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows—jets—that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to propagate through and break out of. Most previous studies have used simple power laws or pre-collapse models for massive stars. However, the relevant stellar profile for lGRB models is in fact that of a star after its core has collapsed to form a compact object. To self-consistently compute such a stellar profile, we use the open-source code GR1D to simulate the core-collapse process for a suite of low-metallicity rotating massive stellar progenitors that have undergone chemically homogeneous evolution. Our models span a range of zero-age main-sequence (ZAMS) masses: M ZAMS = 13, 18, 21, 25, 35, 40, and 45M ☉. All of these models, at the onset of core-collapse, feature steep density profiles, ρ ∝ r −α , with α ≈ 2.5, which would result in jets that are inconsistent with lGRB observables. We follow the collapses of four of the seven models until they form black holes (BHs) and the other three models until they form proto-neutron stars (PNSs). We find, across all models, that the density profile outside the newly formed BH or PNS is well represented by a flatter power law with α ≈ 1.35–1.55. Such flat density profiles are conducive to the successful formation and breakout of BH-powered jets and are, in fact, required to reproduce observable properties of lGRBs. Future models of lGRBs should be initialized with shallower post-collapse stellar profiles, like those presented here, instead of the much steeper pre-collapse profiles that are typically used.
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Boissonnat, Jean-Daniel, Siddharth Pritam, and Divyansh Pareek. "Strong collapse and persistent homology." Journal of Topology and Analysis 15, no. 01 (April 12, 2021): 185–213. http://dx.doi.org/10.1142/s1793525321500296.
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In this paper, we introduce a fast and memory efficient approach to compute the Persistent Homology (PH) of a sequence of simplicial complexes. The basic idea is to simplify the complexes of the input sequence by using strong collapses, as introduced by Barmak and Miniam [DCG (2012)], and to compute the PH of an induced sequence of reduced simplicial complexes that has the same PH as the initial one. Our approach has several salient features that distinguishes it from previous work. It is not limited to filtrations (i.e. sequences of nested simplicial subcomplexes) but works for other types of sequences like towers and zigzags. To strong collapse a simplicial complex, we only need to store the maximal simplices of the complex, not the full set of all its simplices, which saves a lot of space and time. Moreover, the complexes in the sequence can be strong collapsed independently and in parallel. We also focus on the problem of computing persistent homology of a flag tower, i.e. a sequence of flag complexes connected by simplicial maps. We show that if we restrict the class of simplicial complexes to flag complexes, we can achieve decisive improvement in terms of time and space complexities with respect to previous work. Moreover we can strong collapse a flag complex knowing only its 1-skeleton and the resulting complex is also a flag complex. When we strong collapse the complexes in a flag tower, we obtain a reduced sequence that is also a flag tower we call the core flag tower. We then convert the core flag tower to an equivalent filtration to compute its PH. Here again, we only use the 1-skeletons of the complexes. The resulting method is simple and extremely efficient. As a result and as demonstrated by numerous experiments on publicly available data sets, our approach is extremely fast and memory efficient in practice. Finally, we can compromise between precision and time by choosing the number of simplicial complexes of the sequence we strong collapse.
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Liao, Chia Wen, and Tsung Lung Chiang. "Analysis of Collapse Behavior for Demolition of Brick Walls." Applied Mechanics and Materials 166-169 (May 2012): 2765–68. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2765.
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Brick wall collapses contributing to occupational fatalities constantly happen to construction-related workers. The number of workers involved in brick wall collapse accidents is more than that in other accident types. The brick wall collapse accidents accounted for 93% of the structure collapse cases, and about 64% of brick wall collapse cases are in connection with demolition of brick walls. In order to find out the major risks of demolition of brick walls, this article examines occupational accident statistics and case reports from the Northern Region Inspection Office of the Council of Labor Affairs of Taiwan. Discontinuous Deformation Analysis (DDA) is employed to discuss the collapse behavior for demolition of brick walls. A procedure during the demolition of brick walls is suggested for the purpose of safety.
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Gajic, Aleksandar. "Jared Diamond and Peter Turchin: Two contemporary theories of social collapse." Zbornik Matice srpske za drustvene nauke, no. 146 (2014): 85–104. http://dx.doi.org/10.2298/zmsdn1446085g.
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Theories of social collapse are not only the views that characterize ?societies deep in crisis?, but rather an expression of lack of belief in prosperity and central importance of the civilization in which we live. These theories follow processes of degradation of human societies, the decline of civilization`s powers and the loss of its cultural values resulting in their complete disappearance. This paper defines the subject of study and provides an overview of the history of these theories and their contemporary types by taking the main causes of collapse criteria as the basis for theory building. After the review of contemporary multi-factor analysis of collapse, mainly within the science of complex systems, full attention is focused on two atypical, yet very productive, contemporary theories of social collapse that are elaborated in detail: Jared Diamond`s theory, which studies social collapses by observing relations of other variables that can lead to collapse with environmental problems as central; and Peter Turchin`s theory which, revitalizing with modern scientific achievements Ibn Khaldun`s classical theory of ?asabia? (group feeling, spirit of community), sees social collapses as a consequence of the decline of cohesion provided by asabia. The final part of the work gives a critical review of these two theories and their relation with classical theories of social collapse (primarily those of Arnold Toynbee) and points to their mutual productive complementarity.
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GONZALEZ-AVILA, SILVESTRE ROBERTO, EVERT KLASEBOER, BOO CHEONG KHOO, and CLAUS-DIETER OHL. "Cavitation bubble dynamics in a liquid gap of variable height." Journal of Fluid Mechanics 682 (June 21, 2011): 241–60. http://dx.doi.org/10.1017/jfm.2011.212.
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We report on an experimental study of cavitation bubble dynamics within sub-millimetre-sized narrow gaps. The gap height is varied, while the position of the cavitation event is fixed with respect to the lower gap wall. Four different sizes of laser-induced cavitation bubbles are studied using high-speed photography of up to 430,000 frames per second. We find a strong influence of the gap height, H, on the bubble dynamics, in particular on the collapse scenario. Also, similar bubble dynamics was found for the same non-dimensional gap height η = H/Rx, where Rx is the maximum radius in the horizontal direction. Three scenarios are observed: neutral collapse at the gap centre, collapse onto the lower wall and collapse onto the upper wall. For intermediate gap height the bubble obtains a conical shape 1.4 < η < 7.0. For large distances, η > 7.0, the bubble no longer feels the presence of the upper wall and collapses hemispherically. The collapse time increases with respect to the expansion time for decreasing values of η. Due to the small scales involved, the final stage of the bubble collapse could not be resolved temporally and numerical simulations were performed to elucidate the details of the flow. The simulations demonstrate high-speed jetting towards the upper and lower walls and complex bubble splitting for neutral collapses.
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Orihuela-Pinto, Bryam, Agus Santoso, Matthew H. England, and Andréa S. Taschetto. "Reduced ENSO Variability due to a Collapsed Atlantic Meridional Overturning Circulation." Journal of Climate 35, no. 16 (August 15, 2022): 5307–20. http://dx.doi.org/10.1175/jcli-d-21-0293.1.
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Abstract Atlantic meridional overturning circulation (AMOC) collapses have punctuated Earth’s climate in the past, and future projections suggest a weakening and potential collapse in response to global warming and high-latitude ocean freshening. Among its most important teleconnections, the AMOC has been shown to influence El Niño–Southern Oscillation (ENSO), although there is no clear consensus on the tendency of this influence or the mechanisms at play. In this study, we investigate the effect of an AMOC collapse on ENSO by adding freshwater in the North Atlantic in a global climate model. The tropical Pacific mean-state changes caused by the AMOC collapse are found to alter the governing ENSO feedbacks, damping the growth rate of ENSO. As a result, ENSO variability is found to decrease by ∼30% due to weaker air–sea coupling associated with a cooler tropical Pacific and an intensified Walker circulation. The decreased ENSO variability manifests in ∼95% less frequent extreme El Niño events and a shift toward more prevalent central Pacific El Niño than eastern Pacific El Niño events, marked by a reduced ENSO nonlinearity and asymmetry. These results provide mechanistic insights into the possible behavior of past and future ENSO in a scenario of a much weakened or collapsed AMOC. Significance Statement The Atlantic meridional overturning circulation (AMOC) has collapsed in the past and a future collapse due to greenhouse warming is a plausible scenario. An AMOC shutdown would have major ramifications for global climate, with extensive impacts on climate phenomena such as El Niño–Southern Oscillation (ENSO), which is the strongest source of year-to-year climate variability on the planet. Using numerical simulations, we show that an AMOC shutdown leads to weaker ENSO variability, manifesting in 95% reduction in extreme El Niño events, and a shift of the ENSO pattern toward the central Pacific. This study sheds light on the mechanisms behind these changes, with implications for interpreting past and future ENSO variability.
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Majumdar, Arnab, Zoltán Hantos, József Tolnai, Harikrishnan Parameswaran, Robert Tepper, and Béla Suki. "Estimating the diameter of airways susceptible for collapse using crackle sound." Journal of Applied Physiology 107, no. 5 (November 2009): 1504–12. http://dx.doi.org/10.1152/japplphysiol.91117.2008.
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Airways that collapse during deflation generate a crackle sound when they reopen during subsequent reinflation. Since each crackle is associated with the reopening of a collapsed airway, the likelihood of an airway to be a crackle source is identical to its vulnerability to collapse. To investigate this vulnerability of airways to collapse, crackles were recorded during the first inflation of six excised rabbit lungs from the collapsed state, and subsequent reinflations from 5, 2, 1, and 0 cmH2O end-expiratory pressure levels. We derived a relationship between the amplitude of a crackle sound at the trachea and the generation number ( n) of the source airway where the crackle was generated. Using an asymmetrical tree model of the rabbit airways with elastic walls, airway vulnerability to collapse was also determined in terms of airway diameter D. During the reinflation from end-expiratory pressure = 0 cmH2O, the most vulnerable airways were estimated to be centered at n = 12 with a peak. Vulnerability in terms of D ranged between 0.1 and 1.3 mm, with a peak at 0.3 mm. During the inflation from the collapsed state, however, vulnerability was much less localized to a particular n or D, with maximum values of n = 8 and D = 0.75 mm. Numerical simulations using a tree model that incorporates airway opening and closing support these conclusions. Thus our results indicate that there are airways of a given range of diameters that can become unstable during deflation and vulnerable to collapse and subsequent injury.
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Allsop, William, Tom Bruce, and Adrian Pearson. "ORPHAN BREAKWATERS: COLLAPSE AND TRANSMISSION REDUCTION." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 53. http://dx.doi.org/10.9753/icce.v36.structures.53.
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In the past, many coastal towns or villages constructed harbours for trade and/or fishing. These were protected by breakwaters, commonly rubble mounds to low-water, surmounted by vertical walls of dressed stone blocks (later concrete) with rubble core. Now, 100-150 years later, many such harbours have little or no income to maintain or repair their breakwaters, but meantime, the areas protected have been adopted for commercial and residential purposes, at increased risk of flooding if the 'orphan' breakwater were to collapse, Hampshire et al. (2013). Even after collapse, some wave reduction will however still be afforded by the relict structure. Tests by Allsop et al (2017) have modelled the collapse of several simplified breakwaters, and measured levels of wave transmission over the collapsed structures. This paper extends that work with more analysis of collapsed crest levels, and hence of likely wave transmission.
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Xie, Kai Zhong, Guang Qiang Chen, and Li Lin Wei. "A Damage Model for Collapse-Mechanism of Long-Span and High-Pier Continuous Rigid Frame Bridges." Advanced Materials Research 219-220 (March 2011): 1431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.219-220.1431.
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Collapse-mechanism analysis can simulate that bridges enter strong elasto-plastic and large displacement response and collapses phase, so that it is very important for the seismic design of bridges. In this paper, a damage model of reinforced concrete is introduced, and dynamic response and collapse of long span and high-pier continuous rigid frame bridge during strong earthquake is studied with damage model of reinforced concrete by the explicit dynamic analysis code (LS-DYNA). The simulation results indicate the development of the concrete elements from cracking to failure and the bridge from part collapse to the whole collapse of the bridge are studied. The damage and collapse mechanisms during strong earthquake are given of Long Span and High-pier Continuous Rigid Frame Bridges. References are provided for seismic analysis of this kind of bridges.
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Abdel-Wanis, Mohamed El-Sayed, Mohamed Tharwat Mahmoud Solyman, and Nahla Mohamed Ali Hasan. "MRI PATTERN OF VERTEBRAL FRACTURES DUE TO OSTEOPOROSIS, INFECTION, AND MALIGNANT TUMORS." Journal of Musculoskeletal Research 13, no. 02 (June 2010): 57–63. http://dx.doi.org/10.1142/s0218957710002491.
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No previous studies discussed the significance of the MRI pattern of vertebral collapse in differentiation between vertebral compression fractures due to malignancy, osteoporosis, and infections. MRI was used in the evaluation of 152 atraumatic vertebral compression fractures in 80 patients: 85 malignant, 34 osteoporotic, and 33 infective. Central collapse of the fractured vertebral body was the commonest pattern in malignant fractures (57 vertebrae, 67%), followed by uniform collapse (21 vertebrae, 24.7%), then anterior wedging (5 vertebrae, 5.9%), and finally posterior wedging (2 vertebrae, 2.4%). In osteoporotic fractures, anterior wedging was the commonest pattern (18 vertebrae, 53%), followed by central collapse (11 vertebrae, 32.3%), then uniform collapse (4 vertebrae, 11.8%), and finally posterior wedging (1 vertebra, 2.9%). In vertebral compression fractures due to spinal infection, anterior wedging was the commonest pattern (20 vertebrae, 60.6%), followed by uniform collapse (12 vertebrae, 36.4%), while only one vertebra (3%) was centrally collapsed. Central collapse of the vertebral body is highly suggestive of malignant compression fracture while anterior vertebral wedging is highly suggestive of a benign compression fracture.
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M. Ismail, Abdirachid. "The final phase of state collapse : the trap of playing chess." Journal of Somali Studies 7, no. 2 (December 1, 2020): 9–25. http://dx.doi.org/10.31920/2056-5682/2020/7n2a1.
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How do states destroy themselves and become "collapsed states" or "bankrupt states"? After having observed and analyzed the devolution of some countries towards collapse, we took note of at least two factors which are not well documented in literature but which are nevertheless decisive in the collapse of a state.
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Pavlík, Václav, and Ladislav Šubr. "The hunt for self-similar core collapse." Astronomy & Astrophysics 620 (December 2018): A70. http://dx.doi.org/10.1051/0004-6361/201833854.
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Context. Core collapse is a prominent evolutionary stage of self-gravitating systems. In an idealised collisionless approximation, the region around the cluster core evolves in a self-similar way prior to the core collapse. Thus, its radial density profile outside the core can be described by a power law, ρ ∝ r−α. Aims. We aim to find the characteristics of core collapse in N-body models. In such systems, a complete collapse is prevented by transferring the binding energy of the cluster to binary stars. The contraction is, therefore, more difficult to identify. Methods. We developed a method that identifies the core collapse in N-body models of star clusters based on the assumption of their homologous evolution. Results. We analysed different models (equal- and multi-mass), most of which exhibit patterns of homologous evolution, yet with significantly different values of α : the equal-mass models have α ≈ 2.3, which agrees with theoretical expectations, the multi-mass models have α ≈ 1.5 (yet with larger uncertainty). Furthermore, most models usually show sequences of separated homologous collapses with similar properties. Finally, we investigated a correlation between the time of core collapse and the time of formation of the first hard binary star. The binding energy of such a binary usually depends on the depth of the collapse in which it forms, for example from 100 kT to 104 kT in the smallest equal-mass to the largest multi-mass model, respectively. However, not all major hardenings of binaries happened during the core collapse. In the multi-mass models, we see large transfers of binding energy of ∼104 kT to binaries that occur on the crossing timescale and outside of the periods of the homologous collapses.
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Dong, Shuning, Hao Wang, and Wanfang Zhou. "Characterization and Remediation of Karst Collapse Columns for Mining Safety and Environmental Protection: A Case Study in Renlou Coal Mine, China." Environment and Natural Resources Research 8, no. 2 (May 25, 2018): 128. http://dx.doi.org/10.5539/enrr.v8n2p128.
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Karst collapse columns are unique collapse structures in karst terranes. Coal mining in China has exposed numerous such features of tens of meters in diameter and hundreds of meters in height. Hydraulically conductive collapses functioned as groundwater pathways between underground workings and aquifers, resulting in water inrushes during coal mining. Over the last 60 years, water inrushes through these collapses have caused fatalities, economic losses, and degradation in the environment. Determination of locations and hydrogeological characteristics of the karst collapse columns are essential in preventing water inrush incidents through them. Advanced geophysical prospecting, directional drilling, aquifer testing and accompanied dye tracing are effective approaches to detecting and characterizing these structures. Five geophysical techniques consisting of both surface and underground geophysical surveys and directional drilling of three exploratory boreholes up to 986 m deep identified a concealed collapse feature of more than 135 m high in Renlou Coal Mine, China. The roof of the collapse feature was at approximately 785 m deep, and there was an open void of 1.5 - 2 m high at the top. Geotechnical properties, results from packer testing and tracer testing, monitoring of potentiometric pressures, and geochemical fingerprinting suggested that this collapse column was hydraulically conductive and still actively developing. Water in the confined thin-bedded limestone and Ordovician limestone aquifer that either overlies or underlie coal seams could flow into the underground working areas if this feature were not identified in advance but encountered during mining. A grouting program was designed and implemented to construct a water plug in the collapse that effectively cut off the hydraulic connections from the aquifers to the underground workings. Successful construction of the water plug in the collapse was confirmed by performance monitoring of the aquifers.
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Ding, Yanzhi, Qiangyong Zhang, Wen Xiang, Xinrui Lyu, and Longyun Zhang. "Sensitivity Analysis of Mechanical Parameters of Collapse Roof of Carbonate Rock Deep Buried Oilfield." Energies 16, no. 10 (May 17, 2023): 4141. http://dx.doi.org/10.3390/en16104141.
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Carbonate rock oilfields account for two-thirds of proven marine carbonate oilfield reserves, which are the primary way to increase future oil and gas energy reserves. Cave collapses occur during the process of oil reservoir development, seriously affecting oil production. In order to reveal the collapse failure mechanism of carbonate karst caves and predict whether the fracture cave type oil reservoir will collapse before drilling, a binary depth reduction method for determining the critical collapse depth of karst caves is proposed based on the Tahe fracture cave type oil reservoir. The sensitivity of karst cave collapses to multiple factors is analyzed, and a prediction formula for the critical collapse depth of karst caves with changes in the deformation modulus, the internal friction angle, and the cohesion is established through multiple regression analysis. By calculating and analyzing the numerical values of a large number of operating conditions under different mechanical parameters, the failure process, failure mode, and the change law of collapse depth during the Tahe oilfield destruction process were obtained. We used the established formula for predicting the collapse depth of karst caves to predict and analyze the actual distribution of karst caves in the Tahe oilfield. The calculation and analysis results showed that in the karst cave failure mode characterized by vertical shear failure, the cohesive force is the most sensitive factor affecting cave collapse, followed by the internal friction angle. The deformation modulus is hardly sensitive to the influence of the karst collapse. Through the geomechanical model test, the result verified the accuracy and reliability of the calculation results. The research results will provide necessary theoretical support for the large-scale safe extraction of deep petroleum resources, increase oil production in China, and have important theoretical significance and engineering application value.
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Hasegawa, Kazuhiro, Ko Kitahara, Toshiaki Hara, Ko Takano, Haruka Shimoda, and Takao Homma. "Evaluation of lumbar segmental instability in degenerative diseases by using a new intraoperative measurement system." Journal of Neurosurgery: Spine 8, no. 3 (March 2008): 255–62. http://dx.doi.org/10.3171/spi/2008/8/3/255.
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Object In vivo quantitative measurement of lumbar segmental stability has not been established. The authors developed a new measurement system to determine intraoperative lumbar stability. The objective of this study was to clarify the biomechanical properties of degenerative lumbar segments by using the new method. Methods Twenty-two patients with a degenerative symptomatic segment were studied and their measurements compared with those obtained in normal or asymptomatic degenerative segments (Normal group). The measurement system produces cyclic flexion–extension through spinous process holders by using a computer-controlled motion generator with all ligamentous structures intact. The following biomechanical parameters were determined: stiffness, absorption energy (AE), and neutral zone (NZ). Discs with degeneration were divided into 2 groups based on magnetic resonance imaging grading: degeneration without collapse (Collapse[−]) and degeneration with collapse (Collapse[+]). Biomechanical parameters were compared among the groups. Relationships among the biomechanical parameters and age, diagnosis, or radiographic parameters were analyzed. Results The mean stiffness value in the Normal group was significantly greater than that in Collapse(−) or Collapse(+) group. There was no significant difference in the average AE value among the Normal, Collapse(−), and Collapse(+) groups. The NZ in the Collapse(−) was significantly higher than in the Normal or Collapse(+) groups. Stiffness was negatively and NZ was positively correlated with age. Stiffness demonstrated a significant negative and NZ a significant positive relationship with disc height, however. Conclusions There were no significant differences in stiffness between spines in the Collapse(−) and Collapse(+) groups. The values of a more sensitive parameter, NZ, were higher in Collapse(−) than in Collapse(+) groups, demonstrating that degenerative segments with preserved disc height have a latent instability compared to segments with collapsed discs.