基于三维有限差分法的小湾拱坝施工步模拟及极限承载分析

CONSTRUCTION PROCESS SIMULATION AND ULTIMATE BEARING CAPACITY ANALYSIS OF XIAOWAN ARCH DAM BY 3D FINITE DIFFERENCE METHOD

为深入研究高拱坝的破坏机制及安全度,有必要对小湾拱坝这一典型工程的极限承载能力进行重点分析。基于FLAC3D显式有限差分算法,精确模拟小湾拱坝分步施工的全过程;在此基础上利用超载法和强度储备系数法,基于带拉破坏Drucker-Prager和Mohr-Coulomb两种准则,对比分析探讨高拱坝在极限承载过程中破坏机制及其渐进破坏模式;结合破坏区的具体形态,联合采用塑性区贯通、位移突变等方法,评价其整体安全度;分析两准则下高拱坝安全度存在显著差异的原因,指出在评价拱坝的极限承载力方面Mohr-Coulomb准则要优于Drucker-Prager准则;最后,还对材料参数剪胀角、抗拉强度进行了敏感性分析,从中得到一些有益的结论。

To study the final failure mechanism of high arch dam and its safety factor,it's necessary to deeply analyze the ultimate bearing capacity of Xiaowan arch dam which is a typical project. Based on the three dimensional explicit three dimensional finite difference method of FLAC3D,this article accurately simulates the process of the dam construction and water storage.On that base,by using the strength accumulation coefficient method and over loading coefficient method,the ultimate bearing capacity results of Drucker-Prager criterion and Mohr-Coulomb criterion which are all with a tension cutoff are analyzed and compared with each other. Combined with the specific failure deformation,by methods of observing the connected plastic zone in the evolutionary process and recording the sudden change of the dam displacement,the gradual failure mode and the final safety factor of Xiaowan arch dam are found. The reason why the safety factors are significantly different under the two criterions is analyzed,it’s also proposed that the Mohr-Coulomb criterion is better than the Drucker-Prager criterion in the evaluation of the ultimate bearing capacity of arch dam. Finally,a sensitivity analysis on the dilatancy angle and tensile strength is made,and some useful conclusions are found.