基于非线性强度准则的土工结构安全系数有限元计算

将幂律型广义非线性强度准则应用到土工结构安全系数计算中,令土体强度逐渐降低,直至结构破坏,得到最终的安全系数,并开发了基于幂律型广义非线性强度准则的有限元强度折减法程序。该方法不需事先假设滑裂面,计算方便可靠,能适用于各种复杂地质条件。作为算例,该文分别采用线性和非线性两套指标计算了一常见高土石坝和一机场高填方边坡的安全系数。在线性指标下该文方法与PLAXIS内置有限元强度折减法计算结果一致,相对非线性指标,线性指标计算的滑裂面偏浅,计算的安全系数大小随线性参数的确定方法不同而不同。建议使用非线性强度指标计算高围压下土工结构的安全系数。

FINITE ELEMENT ANALYSIS OF EARTH STRUCTURE STABILITY WITH GENERAL NONLINEAR FAILURE CRITERION

The general nonlinear failure criterion of power-law type is implemented in a finite element program to calculate the safety factors of earth structures. The factor of safety is calculated by reducing the strength of the soil until the structure fails. The finite element analysis is superior over other methods since no failure mechanism has to be assumed a priori and is suitable for complex geological conditions. Two numerical examples are presented. One is a high rock dam and the other is a high filled slope. The calculated factors of safety agree well with the results calculated by the PLAXIS software when using the linear Mohr-Coulomb parameters. The failure surfaces calculated by using linear failure criterion are lower than those calculated by nonlinear failure criterion. But the factors of safety can be higher or lower when different calibration methods are used. It is more reasonable to calculate the safety factors of earth structures in high pressure situation with nonlinear failure criterion.