修正的Mohr-Coulomb准则在重力坝建基面抗滑稳定分析中的应用

Application of Modified Mohr-Coulomb Constitutive Model in Anti-sliding Stability Analysis of Gravity Dam Foundation Surface

针对有限单元法在重力坝建基面抗滑稳定控制中量化标准缺失的问题,采用自适应隐式本构积分算法推导了修正的Mohr-Coulomb准则,通过ABAQUS编写成UMAT子程序,用于重力坝建基面抗滑稳定分析,并针对典型重力坝坝型选取常见下游坝坡率,应用强度折减系数法分析了同一网格尺寸下不同坝高对建基面屈服区的影响。结果表明,在对应建基面屈服区贯通率达到15%时的强度折减系数随坝高增加而降低,且在强度折减系数小于1.8时建基面的屈服范围与坝高呈正相关,强度折减系数为1.6时具有明显的线性关系,并结合工程实例验证了结论的可靠性。

To solve the absence of quantitative criterion in finite element method for anti-sliding stability analysis of gravity dam foundation surface, self-adaptive implicit constitutive integral method is used to deduce modified Mohr-Coulomb criterion, which is developed in the UMAT subroutine of ABAQUS. The common downstream dam slope is selected for typical gravity dam. And then the strength reduction coefficient method is used to analyze the impact of different dam height on yield range of foundation surface at the same mesh size. The results show that when the penetrating rate of yield range for foundation surface is 15 %, the strength reduction coefficient decreases with increase of dam height; more over, the yield range of foundation surface is positive related to the dam height when the strength reduction coefficient is less than 1.8 ; while the relationship between the yield range of foundation surface and the dam height is approximately linear when the strength reduction coefficient is equal to 1.6. Finally, the reliability of conclusion is verified by engineering case.