考虑滑坡渐进破坏的改进简布条分法

Improved Janbu slices method considering progressive destruction in landslide

为考虑位移因素对于滑坡渐进性发育的影响,基于简布条分法基本原理,提出一个新的能够考虑滑带土抗剪能力与剪切位移关系的滑坡稳定性简化评价方法。该方法从以下两个方面对简布条分法进行了改进:(1)将滑动面剪应力-剪切位移本构模型与沿滑动面的剪切位移模型相结合,以考虑滑坡随着变形发展渐进破坏的过程;(2)提出局部安全系数的概念并对整体安全系数进行重新定义,物理意义更加明确。推导了该方法的计算公式,给出了其迭代计算思路,并编制Matlab计算程序。通过计算实例表明,应变软化边坡的安全系数不仅取决于土的抗剪强度指标,还与其剪应力-剪切位移关系密切相关,基于峰值强度的极限平衡条分法应用于实际工程是偏于危险的。同时该方法还可以有效地模拟边坡从开始破坏到最终滑动面贯通的发育过程,实现了坡体位移与安全系数之间一一对应的定量关系,进而实现边坡的稳定性的预测预报。

To consider the impact of displacement factor on the progressive development of landslide, a modified Janbu slices method considering the relationship between shear stress and shear displacement of sliding face was presented to evaluate the stability of a landslide. The modified Janbu slices method is improved in the following two aspects： firstly, combined the constitutive shear stress-strain model and shear displacement model along the slide face to simulate the progressive failure process of landslide with deformation development; secondly, the overall safety factor was redefined using concept of partial safety factor with clearer physical meaning. The formula of the simplified method was derived and implemented by Matlab code. An example of simulation shows that the stability factor for slope with strain-softening behavior depends on the strength parameters, and also on the shear stress-shear displacement relationship of slip zone soil. It is unsafe for the limit equilibrium method to be applied to practical engineering, This method can also effectively simulate the development process from the beginning towards the entire sliding face failure of slope. The simulation realizes the quantitative correspondence relationship between displacement and safety factor, and can be used to predict the long-term stability of slope.