求解三维均质边坡安全系数的稳定性图表法研究

Stability charts for determining safety factors of 3D homogeneous slopes

边坡稳定性图表为初步评价边坡的稳定性提供了一种简单但却行之有效的途径。针对现有三维稳定性图表主要是基于极限平衡法和极限分析法提出的不足,采用基于场变量的有限元强度折减法,建立了一套求解三维均质边坡安全系数的稳定性图表。借助ABAQUS软件的二次开发平台UFIELD程序,设置岩土体黏聚力与内摩擦角为场变量的函数,场变量为增量步时间t的函数,从而通过控制增量步时间t实现黏聚力与内摩擦角的折减,通过一次计算即可求得边坡的安全系数,无需手工修改折减系数反复试算。结合3个典型算例对该方法的可靠性进行了验证,并进行了计算效率的比较。结果表明,该方法得到的安全系数可靠,且提高的计算效率。另外,将基于该方法提出的三维均质边坡稳定性图表用于快速获取边坡安全系数、设计边坡坡度和反演滑带土体的强度参数,是合理可行的。

Stability charts provide a simple and effective way to evaluate the preliminary slope stability analysis. Using the strength reduction FEM based on field variable, a series of stability charts are proposed to determine factors of safety for 3 D homogeneous slopes. With the second development platform UFIELD program of ABAQUS, the cohesions and internal friction angles of rock and soil mass are assigned as functions of field variables. The field variables are assigned as a function of step time t, the cohesions and internal friction angles can be reduced with the increase of t, and the safety factor of slopes can be obtained in a single simulation process, which avoids modifying of the input files and without repeating the trial calculation. Based on three typical slope examples, the reliability of this method is validated. The computational efficiency is compared through analysis. The results show that the safety factor obtained by this method is effective and reliable. The computational efficiency is improved. In addition, the proposed stability charts for 3 D homogeneous slopes based on the proposed method are feasible and reliable to rapidly obtain the safety factors, designed slope angles and strength indexes for soils of sliding zone.