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1.
A residual soil slope in Singapore that failed on two occasions, in 1989 and 1991, was reanalysed using two (2D) and three-dimensional (3D) slope stability analyses. The geometry of the slope in 1989 differed from that in 1991. The 2D and 3D slope stability analyses on the slope that failed in 1989 showed that the average shear strength parameters of the residual soils are representative of the slope and the factors of safety obtained from 2D slope stability analyses are not necessarily more conservative than 3D slope stability analyses. The analyses also showed that the slope failed in 1989 due to rising groundwater table. The analyses of the slope in 1991 showed that the slope experienced shallow failure due to the high groundwater table. Analyses of the slope after lowering of groundwater table by horizontal drains showed that the factor of safety of the slope has improved tremendously. The differences in factors of safety for 2D and 3D slope stability analyses are greater for low groundwater table as compared with those for high groundwater table. The results illustrated how 3D slope stability analyses have become less daunting to perform and can be incorporated into routine slope designs. 相似文献
2.
《Geomechanics and Geoengineering》2013,8(3):159-173
The behaviour of the Pleistocene Osaka clays at Kansai International Airport Phase 1 island is investigated by FEM analyses using an elasto-viscoplastic constitutive model which replicates the destruction processes occurring in the microstructure of the clay. Excellent predictions are obtained by 2D analyses carried out using the actual soil profile and the characteristic values of soil parameters, confirming the validity of the methods proposed for characterizing and modelling structured clays. Unlike 1D analyses, where partially effective drainage layers occur, 2D analyses do not require arbitrary pre-definition of the model drainage scenario and of the ‘equivalent’ permeability of interlayered clays to account for macrostructure. In these conditions, 1D analyses must be validated with reference to 2D or 3D prototype analyses and/or well documented experience of comparable work. Once thus validated, 1D analyses are used to investigate the relative merits of possible measures (relief wells, preloading, lightweight fill) aimed at reducing in-service settlement. For future reclamation works at sites where structured clays extend to great depth, filling with lightweight material shows the greatest promise, but it is unlikely to remove the need for designing the superstructure to accommodate the inevitable settlement, which requires accurate prediction. 相似文献
3.
Konstantina Papadopoulou Alexandros Sofianos 《Geotechnical and Geological Engineering》2016,34(6):1877-1887
Some basic factors which influence the behaviour of the anchored retaining structures are investigated and 2D analyses with three dimensional ones are compared. The parametric analysis under 2D conditions focuses on the influence of significant factors such as the normalized embedded depth of the wall, the resistance of the anchors, the free tendon length, the earth pressure coefficient at rest and the flexibility of the system, on the behaviour of the retaining structure. The analyses are performed in two groups for two representative soil types named S1 (weathered weak rock) and S2 (very stiff clay). Qualitative as well as quantitative conclusions are derived from the analyses concerning the influence of the above mentioned factors, mainly on the safety factor as well as on the displacements. The 3D analyses are carried out for various ratios L/H, where L is the length and H the height of the slope. Several trends are confirmed from the results concerning the influence of the above-mentioned factors. It is concluded that the triaxal conditions strongly affect the safety factor, as well as the distribution of horizontal and vertical displacements, mainly in the cases where the ratios L/H ≤ 2. Some serious deviations between 2D and 3D analyses are pointed out and the physical explanation of these differences is given for several cases. 相似文献
4.
William G. Pariseau 《国际地质力学数值与分析法杂志》1981,5(4):429-447
A simple algorithm (PILLR) for obtaining by two-dimensional analysis thee essential results that would be obtained in an actual three-dimensional finite element analysis of stress about mine pillars in flat-laying stratified rock is presented. A series of comparisons between the distributions of the local factor of safety calculated from the results of three-dimensional analysis and that obtained in the PILLR two-dimensional analyses for pillars of length/width ratio ranging from 0.33 to 8.0 shows the algorithm to be quite effective. The average vertical stress over the horizontal mid-plane of the pillar in the PILLR two-dimensional analyses is always within 0.5 per cent of the exact average; the local safety factor distribution is always within 10 per cent of the three-dimensional result. The ratio of the computer core x time product for the 2D' to 3D analyses is approimately 1/150. Additional improvements ard possible, although with the current PILLR algorithm 3D analyses require less than 1 minute for execution. This fact makes technically sound 3D mine pillar design analyses economically feasible on a routine basis. 相似文献
5.
煤矿采区三维地震资料解释中的切片技术及其应用 总被引：3，自引：1，他引：3
长期以来,煤矿采区三维地震勘探资料解释的工作流程与二维地震勘探基本相同,三维地震资料相对二维地震资料所具有的许多解释方面的优越性未能有效发挥出来,人机联作的过程相对简单.在三维地震勘探获取的三维数据体基础上,可做进一步的运算和分析,提取速度、振幅、频率、相位等相关信息,并利用等时切片、层拉平切片、断层切片、面块切片、方差体、相干体等各种技术,有效解释小构造、小褶曲及岩性方面的信息. 相似文献
6.
In this paper the results of 2D FE analyses of the seismic ground response of a clayey deposit, performed adopting linear visco-elastic and visco-elasto-plastic constitutive models, are presented. The viscous and linear elastic parameters are selected according to a novel calibration strategy, leading to FE results comparable to those obtained by 1D equivalent-linear visco-elastic frequency-domain analyses. The influence of plasticity on the numerical results is also investigated, with particular reference to the relation between the hysteretic and viscous damping effects. Finally, different boundary conditions, spatial discretisation and time integration parameters are considered and their role on the FE results discussed. 相似文献
7.
This study uses data from Mao-Luo-Hsi Bridge to model the bridge structure and a set of developed alarm and action values
to formulate guidelines for bridge maintenance and seismic hazard prevention. The bridge model is improved by incorporating
on-site ambient vibration measurement to perform modal analyses. Dynamic analyses of the bridge are implemented using the
established 3D model subjected to uniform loading and seismic force, with or without consideration of soil interaction with
the structure. The maximum displacements for different sections of the bridge are compared, and statistical regression analyses
are used to explore their correlation. Information for bridge safety assessment is proposed, which can mitigate loss of property
and lives due to bridge failure. Regression analyses of the maximum displacements between abutments D and E of the considered
bridge in the axial, horizontal, and vertical directions under various seismic intensities are conducted, giving R
2 values of 0.9462, 0.9352, and 0.9010, respectively. The developed maintenance guidelines are reliable since all parameters
from regression analyses have a 95% confidence interval excluding the zero value. The bridge alarm value and action value
are determined for this bridge site at earthquake intensity scales of 4 and 5, respectively. 相似文献
8.
A series of two-dimensional (2D) and three-dimensional (3D) finite element analyses using the Hardening Soil (HS) model were carried out to investigate the influences of soil properties, wall stiffness, excavation length, excavation depth, clay thickness at the base of the excavation and wall embedment depth, on the maximum wall deflection induced by braced-excavation. The results show that the 3D maximum wall deflections are generally much smaller than those for 2D. Comparisons were also made with other commonly used semi-empirical charts. Based on the finite element results in this study, a simple wall deflection equation was developed for estimating the maximum wall deflection that takes the 3D effects into consideration through different ratios of excavation length over excavation width. 相似文献
9.
《地学前缘(英文版)》2018,9(6):1657-1664
A long slope consisting of spatially random soils is a common geographical feature. This paper examined the necessity of three-dimensional(3 D) analysis when dealing with slope with full randomness in soil properties. Although 3 D random finite element analysis can well reflect the spatial variability of soil properties, it is often time-consuming for probabilistic stability analysis. For this reason, we also examined the least advantageous(or most pessimistic) cross-section of the studied slope. The concept of"most pessimistic" refers to the minimal cross-sectional average of undrained shear strength. The selection of the most pessimistic section is achievable by simulating the undrained shear strength as a 3 D random field. Random finite element analysis results suggest that two-dimensional(2 D) plane strain analysis based the most pessimistic cross-section generally provides a more conservative result than the corresponding full 3 D analysis. The level of conservativeness is around 15% on average. This result may have engineering implications for slope design where computationally tractable 2 D analyses based on the procedure proposed in this study could ensure conservative results. 相似文献
10.
我国CO2捕集与封存的技术路线探讨 总被引：10，自引：0，他引：10
地球温暖化问题已引起全球的密切关注,CO2是促成地球温暖化的主要因素。为了缓解地球温室效应,将大气温室气体浓度稳定在一个安全的水平上,必须减少CO2排放。CO2捕集与封存（CCS）是一种新型岩土工程,具有规模大、潜力大、成本较低、技术成熟度较高、与化石能源结构相容性好等特点,被认为可能具有较高减排贡献度,能够降低综合减排成本和减缓能源结构转变带来的经济冲击。国外已投入了很大的研发资金并且制定了研发路线。中国的研究才刚刚起步,尚未制定开发路线。根据大量调查分析,提出了中国中长期CCS研发技术路线。 相似文献
11.
12.
Impact of range‐parallel sediment transport on 2D thermo‐mechanical models of mountain belts: Application to the Kyrgyz Tien Shan 
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下载免费PDF全文 Evolving mountain belts dynamics is very sensitive to surface processes. The surface processes affect tectonics by enhancing crust exhumation and thermal weakening, and depositing soft yet cold sediments in surrounding basins. While 2D plane strain models approximate cylindrical tectonic structures well, simple 1D mass transfer cannot capture erosion–sedimentation complexity. The Eastern Kyrgyz Tien Shan, where structures, basins and exhumation rates are well constrained, is used here to illustrate this issue. Thermo‐mechanical models demonstrate that 1D transport cannot adjust both basin geometry and Apatite Fission Track exhumation ages. When out‐of‐plane sediment transfer is considered, the amount of evacuated sediment delays or accelerates the formation of new faults, affecting the relative timing of exhumation. For our case study, lateral drainage must evacuate 80% of the sediments to match the geological constraints, which is consistent with other source to sink analyses. This indicates that lateral drainage should not be neglected in regional 2D models. 相似文献
13.
The rock mass structure determines the possible unstable blocks that can induce rock fall phenomena. The stability analyses
must therefore be based on an accurate geo-structural survey. In this work, the stability conditions of several steep slopes
along a motorway in the Far East have been evaluated through key block analysis based on traditional surveys and on laser
scanner acquisitions. Discontinuity orientations and positions on the rock face are derived from the point cloud in order
to perform the reconstruction of the rock mass and to identify blocks in the slope. Results obtained from both the traditional
and the new method is in good agreement. Stability analyses have been performed for evaluating the kinematic feasibility of
different failure mechanisms. The rock block shapes and volumes are computed by performing 2D and 3D analyses whereas the
failure mechanisms are examined using the key block method. Parametrical analyses have been carried on to evaluate the influence
of slope angle variation. DEM models have also been set up. The relative hazard is determined by statistically evaluating
the kinematical feasibility of different failure mechanisms. Hazard mapping has been utilized to identify the best methodology
for risk mitigation. 相似文献
14.
Variscan deformation in the Palæozoic foreland of the Moroccan Anti-Atlas is characterised by its heterogeneous character and its dampening effect towards the Tindouf Basin. Structural analyses shows three sequential episodes of deformation, D1, D2 and D3, displayed at different levels of observation. The first episode D1, which was observed for the first time in the western Anti-Atlas Hercynian Belt provides clear evidence for tangential tectonic deformation operating before the major phase of folding. It corresponds to an early event of ‘thin-skin tectonics’, which develops a composite schistosity related to ductile horizontal pure shearing. It is considered that D1 was responsible for the first folding of the sedimentary sequences associated with several imbricated thrust sheets with vergence to the east. The second episode, D2, represents the major phase of north-northeast-southwest Variscan folding. The D3 episode was more discrete, of brittle type and marked by subequatorial sinistral kink-bands.This D1 tangential event, in the western Anti-Atlas, Morocco, represents a typical structural domain as part of the tectonic evolution during Variscan-Appalachian collision. 相似文献
15.
《地学前缘(英文版)》2022,13(3):101367
New samples returned by China Chang’e-5 (CE-5) mission offer an opportunity for studying the lunar geologic longevity, space weathering, and regolith evolution. The age determination of the CE-5 samples was among the first scientific questions to be answered. However, the precious samples, most in the micrometer size range, challenge many traditional analyses on large single crystals of zircon developed for massive bulk samples. Here, we developed a non-destructive rapid screening of individual zirconium-containing particle for isotope geochronology based on a Micro X-ray fluorescence analysis (µXRF). The selected particles were verified via scanning electron microscopy (SEM), 3D X-ray microscopy (XRM), and focused ion beam scanning electron microscopy (FIB-SEM) techniques, which showed that zirconium-bearing minerals with several microns were precisely positioned and readily suitable for site-specific isotopic dating by second ion mass spectrometry (SIMS). Such protocol could be also applicable in non-destructively screening other types of particles for different scientific purposes. We therefore proposed a correlative workflow for comprehensively studying the CE-5 lunar samples from single particles on nanometer to atomic scales. Linking various microscopic and spectromicroscopic instruments together, this workflow consists of six steps: (1) single-particle selection with non-destructive µXRF technique, (2) 2D/3D morphological and structural characterization with a correlative submicron 3D XRM and nanoscale resolution FIB-SEM imaging methods, (3) SEM analysis of the surface morphology and chemistry of the selected particle, (4) a series of microscopic and microbeam analyses (e.g., SEM, electron probe microanalysis, and SIMS) on the cross-section of the selected particle to obtain structural, mineralogical, chemical, and isotopic features from the micron to nanometer scale, (5) advanced 2D/3D characterization and site-specific sample preparation of thin foil/tip specimens on a microregion of interest in the selected particle with FIB-SEM technique, and (6) comprehensive analyses on the FIB-milled specimens at nanometer to atomic scale with synchrotron-based scanning transmission X-ray microscopy, analytic transmission electron microscopy, and atom probe tomography. Following this technical roadmap, one can integrate multiple modalities into a uniform frame of multimodal and multiscale correlated datasets to acquire high-throughput information on the limited or precious terrestrial and extraterrestrial samples. 相似文献
16.
近几年,建立水利水电三维地质模型成为地质工作者分析工程地质现象和掌握岩土体结构规律的一种新的有用手段。在CATIA软件的基础上,利用Visual Basic.net编程开发了适用于水利水电行业的三维地质建模平台,系统介绍了该三维地质建模平台,该平台包括覆盖层、地质层、水文层、模型分析、模型剖切、有限元分析等基本模块,结合三维地质建模软件提出了地质模型的覆盖层建模流程;针对建模过程中一些关键技术问题做了详细的分析研究,如原始数据处理、曲面分割、曲面缝合等。同时,该软件可实现对已建好的三维地质模型进行质量检测与修复,以保证地质模型的可靠性,最后利用该建模平台建立了某水电站的三维地质模型,利用平台的切割功能实现模型的任意位置、任意角度的二维剖切,以满足工程设计的需要。 相似文献
17.
Rajesh Singh Ravi Kumar Umrao T. N. Singh 《Journal of the Geological Society of India》2017,89(3):295-302
Slope instability is very common phenomenon, especially in tectonically active hills of the lesser Himalaya. The deformed, weathered and fragile rocks of the lesser Himalaya are often vulnerable under natural or anthropogenic influences. There were several cases of slope failure along highway sections in Uttarakhand Himalaya. The study was carried out along a highway section of NH-109. The factor of safety (FoS) is commonly most acceptable parameter that analyses the health of slopes. The two dimensional (2D) numerical analysis techniques are commonly used to obtain the FoS. It is observed that many times FoS obtained from 2D analysis techniques do not qualify the actual conditions and are usually lower in value as compared to ground conditions. This, in turn, increases the cost of remedial measures used for protection of slopes. This paper presents a comparative study of 2D and 3D numerical analysis based on the finite difference method (FDM) using fast Langrangian analysis of continua (FLAC) codes. The study indicates that there is no appreciable difference between FoS values obtained from 2D and 3D analysis based on the selected slope conditions. The difference ranges from 0.02 to 0.07 for analysed cases in uniform rock mass. The study also exhibits some of the important analytical observations and effects of variables on resultant FoS. 相似文献
18.
The water flow into a vertical drain under an embankment loading is axisymmetric problem and therefore, the vertical drain system must be converted into equivalent plane strain model. The matching is achieved by manipulating the drain spacing and/or soil permeability according to relatively simple rules. This paper investigates the verification of matching approaches by comparing 2D plane strain and 3D unit cell results when complex constitutive models are used in the finite element analyses. The numerical results showed that the match was found to be satisfactory but not perfect. A full-scale plane strain analysis is subsequently applied to an embankment case history taken from Haarajoki, Finland, stabilized vertical drains and compared with field measurements. 相似文献
19.
Hongwu Xu Yusheng Zhao Donald D. Hickmott Nina J. Lane Sven C. Vogel Jianzhong Zhang Luke L. Daemen 《Physics and Chemistry of Minerals》2013,40(10):799-810
To study the structural behavior of brucite at high temperature, we conducted in situ neutron diffraction experiments of a deuterated brucite powder sample, Mg(OD)2, in the temperature range 313–583 K. The sample was stable up to 553 K, above which it started to decompose into periclase (MgO) and D2O vapor. Rietveld analyses of the obtained data were performed using both single-site and three-site split-atom hydrogen models. Our results show that with increasing temperature, unit-cell parameter c increases at a rate ~7.7 times more rapidly than a. This large anisotropy of thermal expansion is primarily due to rapid increase in the interlayer thickness along the c-axis on heating. The amplitudes of thermal vibration for Mg, O, and D increase linearly with increasing temperature; however, the rate of the increase for the lighter D is much larger. In addition, D vibrates anisotropically with a higher magnitude within the (001) plane, as confirmed by our first-principles phonon calculations. On heating, the interatomic distances between a given D and its associated O and D from the adjacent [MgO6] layer increase, whereas the O–D bond length decreases. This behavior suggests weakened D···O and D···D interlayer interactions but strengthened O–D bonding with increasing temperature. 相似文献
20.
Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be
in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from
very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding
applications both on the hazard and on the vulnerability part of the risk. In order to shed some light on the question of
required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations
of models of different complexity both on the hazard and on the vulnerability side were tested in a case study. The different
models can be organized in a model matrix of different complexity levels: On the hazard side, the approaches/models selected
were (A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), (B) a mixed 1D/2D
hydraulic model with simplifying assumptions (LISFLOOD-FP) and (C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model
considering the built environment and infrastructure. On the vulnerability side, the models used for the estimation of direct
damage to residential buildings are in order of increasing complexity: (I) meso-scale stage-damage functions applied to CORINE
land cover data, (II) the rule-based meso-scale model FLEMOps+ using census data on the municipal building stock and CORINE
land cover data and (III) a rule-based micro-scale model applied to a detailed building inventory. Besides the inundation
depths, the latter two models consider different building types and qualities as well as the level of private precaution and
contamination of the floodwater. The models were applied in a municipality in east Germany, Eilenburg. It suffered extraordinary
damage during the flood of August 2002, which was well documented as were the inundation extent and depths. These data provide
an almost unique data set for the validation of flood risk analyses. The analysis shows that the combination of the 1D/2D
model and the meso-scale damage model FLEMOps+ performed best and provide the best compromise between data requirements, simulation
effort, and an acceptable accuracy of the results. The more detailed approaches suffered from complex model set-up, high data
requirements, and long computation times. 相似文献