基于非线性破坏准则的三维均质土坡极限分析研究

In the area of slope stability analysis, scholars and engineers generally used the linear Mohr-Coulomb failure criterion, and the slip surfaces of actual slopes are often assumed to be in plane-strain conditions. However, many researchers have found that the strength envelopes for almost all soils are not linear, and the actual slip surfaces of slopes are characteristic of three-dimensional (3D) space. At present, many scholars have carried out the assessments of the slope stability using nonlinear failure criteria. But, they ignored the influences of 3D effect, seismic excitation and pore water pressure on slope stability evaluation. Therefore, this project will utilize the tangential method to combine the nonlinear failure criteria into 3D rotational failure mechanisms. Then, considering the seismic excitation and pore water pressure, the upper-bound limit analysis for the stability of 3D slopes will be established. For several soil slope examples, comparisons of the slope stability with linear and nonlinear failure criteria will be made, to explore the influences of the nonlinear failure criteria on the evaluation of slope stability. The influences of 3D effect, seismic excitation and pore water pressure on the linear and nonlinear results will also be derived, to develop and perfect the slope stability analysis using nonlinear failure criteria. Moreover, for 3D homogeneous soil slopes, calculation and analysis will be conducted to further explore the effects of nonlinear parameters, seismic force and pore water pressure on the slope stability. A series of stability charts will be provided for easy evaluations of the stability of 3D homogeneous soil slopes. These results can give several suggestions for the slope engineering design and landslide reinforcements.

在边坡稳定性分析中，学者和工程师们普遍采用的是线性Mohr-Coulomb准则，且对实际边坡进行了平面应变假设。然而，大量学者发现了岩土介质的非线性强度特点，且实际边坡滑动面具有三维空间特性。针对已有的非线性破坏准则下边坡稳定性分析方法忽视了三维效应、地震作用和孔隙水压力的影响，本项目利用切线技术将非线性准则与三维转动破坏机制结合，建立地震作用和孔隙水压力下三维均质土坡的极限分析上限解法。基于几种黏土边坡算例，通过对比非线性与线性准则下边坡稳定性，探索非线性准则对边坡稳定性评价的意义，并揭示三维效应、地震作用和孔隙水压力对线性与非线性准则下边坡稳定性评价差异的影响规律，发展和完善非线性准则下边坡稳定性分析研究。针对三维均质土坡，探索非线性参数、地震作用、孔隙水压力对边坡稳定性的影响规律，并提供可快速评价三维均质土坡稳定性的稳定图表，为边坡工程设计和滑坡治理提供可靠的计算理论和参考依据。

大量研究表明：岩土体具有非线性强度特点，实际边坡滑动面具有三维空间特性。近年来，很多学者开展了非线性准则下二维边坡稳定性评价，但关于非线性与线性准则下边坡稳定性评价差异的研究较少。目前，非线性准则下三维边坡稳定性极限分析研究较少，三维效应、地震作用和孔隙水压力对边坡稳定性的影响有待进一步探索。针对目前研究不足，本项目利用切线技术将非线性准则与三维转动破坏机制结合，建立了考虑地震力和孔隙水压力的三维边坡极限分析上限解法。针对几种典型黏土边坡，通过非线性与线性准则下边坡稳定性的对比，发现：采用线性准则进行边坡稳定分析将会产生不可忽视的高估或低估，特别是对于三维效应明显的边坡；当边坡受到地震力或存在孔隙水压力时，非线性与线性准则下边坡稳定性差异将更为凸显。对于三维均质土坡，探究了非线性参数、三维效应和地震力对边坡稳定系数、等效Mohr–Coulomb参数和最危险滑动面的影响，结果表明：边坡越缓、三维效应越显著、地震力越小时，非线性参数对边坡稳定性的影响越明显；边坡滑动面的三维特性除了与边坡宽高比有关，还受到非线性参数和地震力的影响；等效Mohr–Coulomb参数主要与非线性参数有关。本项目绘制了一系列三维土质边坡的稳定图表，为边坡稳定性评价提供了参考。