边坡临界失稳状态的判定标准

为了建立边坡临界失稳状态的统一判据，对同一算例分别实施3种判据：塑性区贯通判据、计算不收敛判据、位移突变判据.采用拉格朗日元法对边坡进行弹塑性稳定分析，将3种判据得到的安全系数与Janbu法的结果进行对比.结果表明：塑性区贯通并不一定产生边坡失稳，该判据得到的安全系数偏小；计算不收敛判据得到的安全系数与Janbu法十分接近，但其无法反映边坡的变形过程，且具有一定的人为任意性；位移突变判据确定了边坡稳定形态与折减系数的定量关系，通过双曲线方程拟合可方便地得到安全系数，其求解精度高，物理意义明确.

The standards for critical failure state of slope

In order to build the uniform failure criterion of slope, different failure criteria,the connectivity of plastic zone criterion;the convergence of numerical computations criterion;the mutation of displacement criterion,were built for the same calculation model.The elastoplastic analysis was done to the stability of slope by the method of fast lagrangian analysis of continua three dimensions(FLAC3D).Safety factors obtained from the three criteria were compared with that from Janbu's procedure of limit equilibrium.The comparative analyses were done.Results show that connectivity of plastic zone dose not always indicate the failure of slope,safety factor obtained from the connectivity of plastic zone criterion is in a smaller value;safety factor obtained from convergence of numerical computations criterion is close to that from Janbu method,but it can not show the deformation procedure of slope,there are some artificial uncertain factor in this criterion;the relationship between slope stability and reduction factor is founded by displacement mutation criterion,and safety factor can be easily obtained by curve fitting which shows good correlation with the monitoring data;the displacement mutation criterion has high degree of precision and clear physical meaning.