基于强度折减法的三维边坡失稳判据

Instability criterion of three-dimensional slope based on strength reduction method

为了寻求基于强度折减法的三维边坡稳定分析的合理判据,依托珍珠坝边坡采用FALC3D对位移突变判据及塑性区贯通判据进行分析,并与ANSYS计算结果和二维极限平衡结果进行比较。结果表明:在采用强度折减法对三维边坡稳定分析时,位移突变判据根据总位移增量和折减系数关系曲线较易识别突变点且特征点选在边坡坡顶滑体上较为合理;针对塑性区贯通判据的不足,提出了以贯通率增量和折减系数曲线上的突变点来判别边坡稳定性。因此,三维边坡失稳判据的合理选用应遵循以下原则:建议在滑带明确的情况下采用塑性区贯通率增量突变判据,在滑带未知的情况下采用位移增量突变判据。

For the purpose of trying to find a reasonable criterion for stability analysis of three-dimensional slope based on strength reduction method, the displacement mutation criterion and the connectivity criterion of plastic zone are analyzed based on Zhenzhuba slope by FLAC3D; and then the results are compared with the ANSYS and two-dimensional limit equilibrium＇s ones. It is shown that, in the stability analysis of three-dimensional slope using strength reduction, mutations are easily identified in the curve between the increments of total displacement and reduction factors and reasonable feature points should be selected on the top of the slope for the displacement mutation criterion. Meanwhile, a modified criterion is put forward due to the shortcomings of the connectivity of plastic zone criterion. It is that the mutations, which are on the curve between the increments of penetration rate of the plastic zone and reduction factors, are used to judge the instability state of three-dimensional slope. So the reasonable choice of three-dimensional slope＇s instability criterion should be as follows. If the slip band is known clearly, the increments of penetration rate of the plastic zone criterion is suggested; if not, the displacement increment mutation criterion is suggested.