极限平衡法与FLAC-3D模拟方法在边坡稳定分析中的对比研究

发布时间：2018-04-13 02:13

本文选题：滑坡体 + 稳定分析　；参考：《昆明理工大学》2015年硕士论文

【摘要】：极限平衡法和FLAC-3D数值模拟是目前常用的两种边坡稳定性分析方法,具有相应的特点及有待完善之处。本文借助绘图软件和有限元分析软件解决了FLAC-3D直接建模的困难,结合工程实例进行对比研究,明晰了两种方法的误差机制,并提出了结合运用、互相验证、接力计算的设想。极限平衡理论的误差主要来源于：简化了边坡土体中力的作用方式和作用位置；滑体条分数量的随意性较大；圆弧滑动面仅与均质土坡相符,其它滑动面又带有一定的随机性和主观因素。研究实例中的滑动面由经验给出,导致多数剖面上的滑动面与计算结果不吻合,滑动面也并非像极限平衡法指定的那样,严格处于第四系滑坡堆积层和全-强风化泥岩层的岩层分界面上。运用极限平衡法研究边坡稳定性时,建议选择多种不同的模型计算同一个对象,然后用所有计算结果来求平均值,如此可望减小单一模型造成的误差。FLAC-3D数值模拟技术偏重于岩土体的应力和应变分析,与边坡变形、破坏的实际过程更为相符,但单元网格的划分精细程度,同样会影响模拟结果的准确性。该软件可以在三维层面上研究岩土对象,能充分考虑设定范围内的岩层展布情况及岩层之间的变形协调,保持了实际地质的结构特征,因此较之二维分析更为准确、直观。FLAC-3D展示的剖面塑性应变增量云图,很清晰地显示出边坡的可能滑动面以及滑动周界,甚至可给出不同区域的量化位移。对潜在滑坡体进行三维数值模拟的困难在于：建模过程复杂、计算过程冗长,所消耗的时间远远超过极限平衡法。建议借助于绘图软件GoCAD提取点数据,在Surfer中进行插值,并在ANSYS中建立三维边坡网格模型,最后借助插件实现模型转换,将模型导入FLAC-3D进行赋值计算。在对边坡工程进行稳定性分析时,建议结合前述两种方法的优点,互相验证、接力计算。例如：可先用FLAC-3D进行数值模拟,得出边坡的可能滑动面,然后用极限平衡法求其稳定系数与剩余下滑力,如此可望获得更为准确的分析结论。
[Abstract]:Limit equilibrium method and FLAC-3D numerical simulation are two commonly used slope stability analysis methods, which have the corresponding characteristics and need to be improved.In this paper, drawing software and finite element analysis software are used to solve the difficulty of FLAC-3D direct modeling. The error mechanism of the two methods is clarified by comparing with engineering examples, and the assumption of combining application, mutual verification and relay calculation is put forward.The error of the limit equilibrium theory mainly comes from: simplifying the action mode and position of the force in the slope soil; the random number of slider sections; the arc sliding surface is only consistent with the homogeneous soil slope.Other sliding surfaces also have some randomness and subjective factors.The slip surface in the study example is given by experience, which results in that the sliding surface on most sections does not agree with the calculated results, and the sliding surface is not as specified by the limit equilibrium method.It is strictly on the boundary of the Quaternary landslide accumulation layer and the fully weathered mudstone layer.When the limit equilibrium method is used to study slope stability, it is suggested to select several different models to calculate the same object, and then use all the results to find the average value.It is expected to reduce the error caused by a single model. FLAC-3D numerical simulation technology is more suitable for the stress and strain analysis of rock and soil, which is more consistent with the actual process of slope deformation and failure.It also affects the accuracy of the simulation results.The software can study the geotechnical objects on the three-dimensional level, and can fully consider the distribution of the strata and the deformation coordination between the strata within a given range, thus maintaining the structural characteristics of the actual geology, so it is more accurate than the two-dimensional analysis.The incremental plastic strain cloud diagram of section displayed by visual. FLAC-3D clearly shows the possible sliding surface and the slip boundary of the slope, and even gives the quantitative displacement of different regions.The difficulty of 3D numerical simulation of potential landslide is that the modeling process is complicated, the calculation process is long, and the time consumed is far more than the limit equilibrium method.It is suggested to interpolate the data in Surfer with the help of drawing software GoCAD, and establish a 3D slope mesh model in ANSYS. Finally, the model is transformed by plug-in, and the model is imported into FLAC-3D to calculate the value.In the stability analysis of slope engineering, it is suggested that the advantages of the two methods be combined to verify each other and calculate the relays.For example, the possible sliding surface of slope can be obtained by numerical simulation with FLAC-3D, and then the stability coefficient and residual sliding force can be calculated by the limit equilibrium method, which is expected to obtain a more accurate analytical conclusion.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.2

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