基于遍布节理模型的边坡稳定性强度折减法分析

Slope stability analysis by strength reduction method based on ubiquitous-joint model

采用非线性数值分析方法分析边坡稳定性问题时,强度折减法因其具有较多的优点而得到广泛应用。岩土体一般采用理想弹塑性模型,屈服准则为广义米赛斯准则。对于密集节理岩质边坡稳定性问题,采用遍布节理模型可同时考虑岩块和节理属性,更符合岩体状态及工程实际,认为岩体经强度折减后潜在破坏可能首先出现在岩体中或沿节理面或二者同时破坏。结合工程实例,基于遍布节理模型的强度折减法计算结果表明,潜在滑移面为折线型滑面,下部潜在滑移面倾角与节理面等效内摩擦角基本一致,上部潜在滑移面与岩体拉破坏相关;节理倾角与边坡安全系数、潜在滑动范围密切相关,陡倾角节理对边坡稳定性影响较小。通过对边坡失稳判据和边坡滑移面确定的探讨,认为以力或位移不收敛作为边坡失稳判据是适当的,而边坡的剪应变速率物理意义十分明确,适于作为边坡潜在滑移面的确定依据。

Due to the merits of strength reduction method, it has been broadly used in nonlinear numerical analysis of the slope stability, In general, the rock and soil are regarded as to be an idealized elastoplastic model; and Mises yield criterion is used, The stability analysis of densely jointed rock slopes using ubiquitous-joint model, the joint property can be considered as well as the rock, thus fitting better with the practical engineering, It is assumed that failure might occur first either in rock or along joint or in both during the rock strength reduction, According to a real engineering project and based on strength reduction method with ubiquitous-joint model, the calculation results show that the potential slip surface appears in style of a polygonal plane; and the dip angle of the potential slip near slope foot is similar to the equivalent friction angle of joint, while the potential slip near the top slope is related to tension failure of rock. The results also show that the dip angle of the joint determines the slope safety factor and the potential slip range. The steeper joint sets affect less the slope stability. Throughout the investigation of the slope failure criteria and the slip surface, it is recognized that the case of the force or displacement becoming not convergent can be properly used as the failure criteria of slope. The shear strain rate in slope can also be used as the criteria for confirming the potential slip of slope because its physical meaning is very explicit.