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1.
边坡落石灾害的颗粒流模拟方法 总被引：5，自引：0，他引：5
落石是边坡的一种常见的动力地质灾害。基于颗粒流理论,提出了落石灾害的二维的可视化模拟方法。通过颗粒流中不同参数的ball单元的组合模拟了各种形状和特性的落石体;通过wall单元的组合模拟坡面;选择ball-ball和ball-wall的接触刚度模型、粘结模型和滑移模型等接触本构模型来反映落石运动过程中落石岩块内部各部分和落石与坡面作用行为;实现了边坡落石灾害的二维可视化模拟。模型模拟出落石的自由落体、弹跳、滑动和滚动等运动形式、运动过程岩块的崩解;得到了落石的运动速度、位移等运动学参数。工程实例初步验证了该方法的可行性、合理性。 相似文献
2.
Yi-Long Chang Tsung-Hsien Chen Meng-Chia Weng 《Rock Mechanics and Rock Engineering》2012,45(5):851-862
This study proposes a modified eccentric circle model to simulate the rolling resistance of circle particles through the distinct element method (DEM) simulation. The proposed model contains two major concepts: eccentric circle and local rotational damping. The mass center of a circular particle is first adjusted slightly for eccentricity to provide rotational stiffness. Local rotational damping is adopted to dissipate energy in the rotational direction. These associated material parameters can be obtained easily from the rolling behavior of one rod. This study verifies the proposed model with the repose angle tests of chalk rod assemblies, and the simulated results were satisfactory. Simulations using other existing models were also conducted for comparison, showing that the proposed model achieved better results. A landslide model test was further simulated, and this simulation agreed with both the failure pattern and the sliding process. In conclusion, particle rolling simulation using the proposed model appears to approach the actual particle trajectory, making it useful for various applications. 相似文献
3.
将二维均质土坡作为平面应变问题,假定滑动面是一个圆弧,将滑弧圆心与半径转变为后缘剪入点、坡脚剪出点和过后缘点滑弧切线与x轴的交点等3个点的横坐标,然后以这3个参数为变量,给定合理的取值区间,应用黄金分割法搜索二维边坡的最小稳定系数及相应的临界滑动面。进一步假定均质土坡的三维空间滑动面为一旋转椭球体,旋转椭球体的竖向中轴面和二维的圆弧面一致,给定椭球体不同的水平轴半径值,采用以上二维滑动面搜索方法可求出不同水平半径所对应的三维最小稳定系数及相应的椭球面。结果表明：边坡的三维稳定系数没有极小值,但有极限值;对于横向延伸长的无限边坡,三维稳定系数逼近二维稳定系数,当旋转椭球长轴与短轴之比大于3时,二者很接近,边坡稳定性可简化为二维来分析;对于受地形、地下水等条件约束的短边坡,三维效应明显,在考虑实际边界条件的情况下按三维来分析。 相似文献
4.
A GIS-based logistic regression model in rock-fall susceptibility mapping along a mountainous road: Salavat Abad case study, Kurdistan, Iran 总被引：1，自引：0，他引：1
This study describes the application of logistic regression to rock-fall susceptibility mapping along 11?km of a mountainous road on the Salavat Abad saddle, in southwest Kurdistan, Iran. To determine the factors influencing rock-falls, data layers of slope degree, slope aspect, slope curvature, elevation, distance to road, distance to fault, lithology, and land use were analyzed by logistic regression analysis. The results are shown as rock-fall susceptibility maps. A spatial database, which included 68 sites (34 rock-fall point cells with value of 1 and 34 no rock-fall point cells with value of 0) was developed and analyzed using a Geographic Information System, GIS. The results are shown as four classes of rock-fall susceptibility. In this study, distance to fault, lithology, slope curvature, slope degree, and distance to road were found to be the most important factors affecting rock-fall. It was concluded that about 76?% of the study area can be classified as having moderate and high susceptibility classes. Rock-fall point cells were used to verify results of the rock-fall susceptibility map using success curve rate and the area under the curve. The verification results showed that the area under the curve for rock-fall susceptibility map is 77.57?%. The results from this study demonstrated that the use of a logistic regression model within a GIS framework is useful and suitable for rock-fall susceptibility mapping. The rock-fall susceptibility map can be used to reduce susceptibility associated with rock-fall. 相似文献
5.
斜坡滚石运动速度特征与坡表覆盖层特征、滚石形状、坡面角度、滚石质量等主要因素有关,选择不同坡表覆盖层,对不同形状、质量的滚石,采用低角度直线坡段设计正交试验（L27（34））,研究斜坡滚石滚动状态下速度特征。分析得到滚石斜坡运动影响因子排序:坡表特性X1、坡角X3、滚石形状X2、滚石质量X4。回归分析得出斜坡滚石运动估算速度公式:vc=-7.85X10.50+0.47X23.22+2.97X30.24,与试验实测值进行对比,得出相对误差为8.2%,相关系数为r=0.92。利用回归方程分析单因素的影响趋势,结果表明:坡表特征与速度有明显线性负相关关系、滚石形状与速度呈上凹型曲线、坡角与速度呈下凹型曲线的数学关系。通过现场试验,实测得到斜坡滚石速度计算简化修正公式v=v0+(L/2.45) vc,对比验证与实测结果吻合较好,证明了本文计算公式对于总体平直、角度局部变化的直线型斜坡的适用性和有效性。所得成果可估算斜坡滚石的速度与冲击能量,对滚石防治措施的选择有参考价值。 相似文献
6.
7.
块体理论在潜在崩塌体稳定性分析中的应用 总被引：3，自引：0，他引：3
随着国民经济的快速发展,公路、铁路、水利水电、矿山等工程建设的高陡岩质边坡越来越多,崩塌的问题就越来越突出。由于崩塌地质灾害给公路、铁路工程建设和运营安全造成严重的威胁,为了有效防止崩塌地质灾害的发生,保护人民生命财产的安全,文章提出在边坡工程地质调查基础上,采用块体理论,预测边坡潜在的崩塌范围。而块体理论是近年来发展和完善的一种适合于岩体稳定性分析的行之有效的工程分析方法。文章采用块体理论中的矢量分析法与赤平投影相结合的方法,用Matlab软件开发了相应的计算机程序,将其应用于潜在崩塌岩体的稳定性分析,可自动找出可动块体,为崩塌地质灾害的监测预报以及治理等提供了依据。 相似文献
8.
In recent years, blocks created by pressure grouting of cement into soil were used to reinforce slopes by targeting specific weak areas. A clear understanding of the block reinforcement mechanism is essential for the accurate evaluation of the stability of block-reinforced slopes and reasonable design of block layouts. A series of centrifuge model tests was conducted to investigate the bearing capacity and the full deformation and failure behavior of block-reinforced slopes, with a focus on the influence of block layouts on the reinforcement effect. A block reinforcement with a reasonable layout was confirmed to increase the stiffness and the ultimate bearing capacity of the slope. The block reinforcement significantly changed the failure mode to the complex disturbance and destruction from slippage failure in an unreinforced slope. The block reinforcement restrained the deformation localization around the blocks and thus prevented the development of the coupling effect between the deformation localization process and the failure process in an unreinforced slope during loading. Such a reinforcement mechanism could be used to explain why the block reinforcement increased the bearing capacity and changed the failure mode of the slope. The blocks exhibited significant motion along with the development of deformation localization in the slope during loading. The block reinforcement effect was significantly affected by the rotation of blocks, which was determined by the block layout. 相似文献
9.
土石混合体是由软弱的土颗粒与刚度较大、强度较高的块石混合而成,因此土石混合体边坡失稳时,其滑动面受块石-土形成的细观结构特征影响,导致边坡稳定性分析存在诸多困难。本文基于一典型的土石混合体边坡,建立颗粒离散元数值模型,通过室内试验标定土体细观参数,结合强度折减法分析土石混合体边坡与纯土体边坡破坏模式及滑面形态的差别。结果表明:块石的存在使得土石混合体边坡的接触力链分布极不均匀,块石的存在使接触力链形成闭环,增大了滑动面积,对边坡有加固作用;土石混合体边坡的滑面发展趋势总倾向于穿过块石间的缝隙,滑面的发展与块石分布状况相关联;当块石含量达到20%以上时,边坡稳定性显著提高;块石含量达到30%~50%时,滑坡以局部块体运动为主,无法形成连续的滑动面。研究成果可为土石混合体边坡的变形破坏机理分析提供依据与参考。 相似文献
10.
A new rock mass failure criterion for biaxial loading conditions 总被引：1，自引：0，他引：1
P. H. S. W. Kulatilake Jinyong Park Bwalya Malama 《Geotechnical and Geological Engineering》2006,24(4):871-888
To simulate brittle rocks, a mixture of glastone, sand and water was used as a model material. Thin galvanized sheets of thickness
0.254 mm were used to create joints in blocks made out of the model material. To investigate the failure modes and strength,
both the intact material blocks as well as jointed model material blocks of size 35.6 × 17.8 × 2.5 cm having different joint
geometry configurations were subjected to uniaxial and biaxial compressive loadings. A new intact rock failure criterion is
proposed at the 3-D level. This criterion is validated for biaxial loading through laboratory experimental results obtained
on intact model material blocks. Results obtained from both the intact and jointed model material blocks are used to develop
a strongly non-linear new rock mass failure criterion for biaxial loading. In this failure criterion, the fracture tensor
component is used to incorporate the directional effect of fracture geometry system on jointed block strength. The failure
criterion shows the important role, the intermediate principal stress plays on rock mass strength. 相似文献
11.
A discrete element code with impact model has been developed and calibrated to simulate the dynamic behavior of rock materials, with special regard to rock fragmentation upon impact during rock-fall analysis. The paper summarizes the discrete element code, the calibration algorithms developed to identify the model microparameters, and the impact model. Experimental work on drop tests is then used to validate the code on modeling impact fragmentation. It has been found that the developed discrete element code and impact model can reasonably simulate rock fragmentation in drop tests. The use of the discrete element code and impact model can provide good reference results in evaluating impact fragmentation in rock-fall analysis. 相似文献
12.
裂隙岩体一般块体理论初步 总被引：9，自引：0，他引：9
本文在前人工作的基础上提出了一种通用方法解决任意大小裂隙、任意形状工程岩体的岩石块体识别及稳定性计算问题。在这一方法中裂隙既可以是实测裂隙也可以是通过随机模拟方法生成的随机裂隙,工程岩体可以是任意由多面体组合成的形状,如复杂边坡或地下洞室,而且岩体和裂隙面可以是非均质的。这一通用过程被称为一般块体理论。它克服了关键块体理论(或楔形体法)中存在的弱点:即把裂隙假设为无限大的不连续面,因此无法预测岩石块体的数量和位置,而且一般只能识别出简单形状的凸形体。它在块体识别的同时将复杂的块体分解为几个简单的凸形块体,从而使复杂块体的几何描述、体积及重力计算、力学分析、可视化表示等一系列问题大大简化。在对一公路边坡的裂隙进行了详细观测之后,利用本文的方法进行了块体识别和稳定性分析,对本文的研究进行初步的验证。 相似文献
13.
边坡稳定性问题是川藏线工程建设面临的重要问题。野外调查发现基岩边坡失稳一般表现为块体塌落或滑动。基于岩体结构控制理论,作者以川藏线西藏境内宿瓦卡附近的人工高边坡为例,进行了块体边坡稳定性分析。对比现有理论方法的优缺点,采用坐标投影作图法及其计算机化程序CPH。坐标投影作图法是一种以正投影为基础,以分析岩体结构面的几何关系及由其切割出来的块体的稳定性为目的的图解方法。根据现场量测取得的数据,采用CPH程序确定了块体边坡的结构面方程,从而求出各结构面产状。在此基础上建立水平切面图,并求得各块体顶点坐标,计算出块体的表面积及体积。根据极限平衡理论,运用CPH程序进行块体稳定性分析,并求出块体的稳定性系数。通过分析可知,坐标投影作图法及其计算机化的CPH程序在块体边坡稳定性分析中有着很好的应用效果。 相似文献
14.
15.
《Geomechanics and Geoengineering》2013,8(2):107-111
The stability of eccentrically loaded strip footings on slopes was investigated using the method of finite element analysis based on the theory of elasto-plasticity. The analysis was done for two different soils involving three levels of slope angle, six footing locations, and two levels of load eccentricity plus central vertical loading. The strip footing analysed was a 3-ft (0.9 m) wide reinforced concrete footing embedded to a depth of 3 ft (0.9 m). The analysis focused on footing settlement, plastic yielding of soil, and ultimate bearing capacity. The results of analysis show that the influence of load eccentricity on footing pressure vs. footing centre settlement is negligibly small. However, the progressive soil yielding and ultimate bearing capacity are greatly affected by load eccentricity. Furthermore, the effect of load eccentricity differs considerably with the load location relative to the footing centre and slope crest. The ultimate bearing capacity for the eccentric load located on the slope side is significantly greater than that for the load located on the other side of the footing centre. For a 2(H): 1(V) slope in silty clay, the effect of slope on footing stability decreases with increasing footing location from slope crest as would be expected, and diminishes when the footing is located from the crest at about 5-times the footing width. 相似文献
16.
A fractal fragmentation model for rockfalls 总被引：1，自引：0，他引：1
The impact-induced rock mass fragmentation in a rockfall is analyzed by comparing the in situ block size distribution (IBSD) of the rock mass detached from the cliff face and the resultant rockfall block size distribution (RBSD) of the rockfall fragments on the slope. The analysis of several inventoried rockfall events suggests that the volumes of the rockfall fragments can be characterized by a power law distribution. We propose the application of a three-parameter rockfall fractal fragmentation model (RFFM) for the transformation of the IBSD into the RBSD. A discrete fracture network model is used to simulate the discontinuity pattern of the detached rock mass and to generate the IBSD. Each block of the IBSD of the detached rock mass is an initiator. A survival rate is included to express the proportion of the unbroken blocks after the impact on the ground surface. The model was calibrated using the volume distribution of a rockfall event in Vilanova de Banat in the Cadí Sierra, Eastern Pyrenees, Spain. The RBSD was obtained directly in the field, by measuring the rock block fragments deposited on the slope. The IBSD and the RBSD were fitted by exponential and power law functions, respectively. The results show that the proposed fractal model can successfully generate the RBSD from the IBSD and indicate the model parameter values for the case study. 相似文献
17.
Failure mechanism in an extremely slow rock slide at Bitchu-Matsuyama castle site (Japan) 总被引：1，自引：1，他引：1
One of the specific problems related to historical structures is the fact that they are prone to damage caused by even very
small deformations acting over a long period of time, such as creep or extremely small rock displacements. If any damage has
already occurred, the determination of the rock slope failure mechanism is one of the prerequisites for successful mitigation
technique selection. In this study a medieval castle in central Japan, suffering damage caused by deformation of the rock
mass in the subgrade of the castle, was investigated using a combination of field investigation, high-precision monitoring
and physical modeling experiments. Using these techniques an attempt to determine the failure mechanism of the rock slope
was made. Based on the field investigation a toe-slope failure seemed to be the main triggering factor activating the deformations
in the upper slope area, right below the defense walls of the castle. The displacement monitoring of the surface rock blocks
revealed a slumping failure with the backward rotational component prevailing over the sliding in the immediate vicinity of
the castle wall. This was in accordance with the expectations obtained from the structural analysis of the rock mass carried
out during the field investigation. The displacements obtained during the rock block monitoring, especially from the crack
gauges, were not sufficient for drawing a satisfactory conclusions about the failure mechanism of the blocks located in the
central part of the slope. Therefore, the failure mechanisms of rock blocks inferred from their displacements obtained from
the monitoring were correlated with the results of modeling experiments carried out on the scaled slope model. The physical
modeling revealed a possibility of toppling failure of rock blocks in the central area of the slope caused mainly by block
interlocking, which was supported by the data from surface tilt meters installed additionally in the field. Furthermore, the
possibility of the occurrence of forward and backward rock block rotations in the same sliding body at given conditions was
supported by the physical modeling experiments. 相似文献
18.
Experimentally gained parameters,decisive for rock fall analysis 总被引：5，自引：0，他引：5
Summary This paper presents the methodology adopted for assessing experimental parameters relevant to computer rockfall analyses and describes the data gathered from several in situ rockfall tests carried out by ISMES and ENEL CRIS during recent years.Through the calculation of block velocities during their fall from and onto slopes of various geometry, and the measurement of the run-out distances, heights of bounce and the geometric characteristics of blocks, the following experimental parameters were studied: Restitution Coefficient, Rolling Friction Coefficient, dispersion of trajectories, effect of block geometry on its fall, and efficiency of a ditch, at the bottom of a slope, for arresting fallen blocks. 相似文献
19.
The study investigates the possibility to incorporate fracture intensity and block geometry as spatially continuous parameters in GIS-based systems. For this purpose, a deterministic method has been implemented to estimate block size (Bloc3D) and joint frequency (COLTOP). In addition to measuring the block size, the Bloc3D Method provides a 3D representation of the shape of individual blocks. These two methods were applied using field measurements (joint set orientation and spacing) performed over a large field area, in the Swiss Alps. This area is characterized by a complex geology, a number of different rock masses and varying degrees of metamorphism. The spatial variability of the parameters was evaluated with regard to lithology and major faults. A model incorporating these measurements and observations into a GIS system to assess the risk associated with rock falls is proposed. The analysis concludes with a discussion on the feasibility of such an application in regularly and irregularly jointed rock masses, with persistent and impersistent discontinuities. 相似文献
20.
基于传统块体理论对不连续岩体的稳定分析是建立在不连续面贯穿所研究岩体的假定基础上的，而实际的岩体不连续而长度是有限的。因此，本文将随机概率模型张块体理论，研究了三峡永久船闸边坡关键块体的肖落概率和块体的大小及分布密度，结果表明该方法具有重要的工程实用价值。 相似文献