静、动力分析中的一种初始地应力场平衡方法

初始地应力场的平衡对于正确分析模拟具有围压依赖性和接触的问题尤其重要,准确模拟初始应力场是后续岩土工程动力响应分析正确与否的关键。为了实现岩土工程分析中初始竖向位移为零,且初始应力场不影响后续动力分析结果,基于ABAQUS软件,提出一种静、动力分析问题中的初始地应力场平衡方法。首先将人工边界考虑为固定边界,施加重力场,并求出边界节点上的反力;其次,将节点上的反力施加在黏弹性人工边界模型场地中,进行初始应力场平衡;最后,进行动力分析,并用理论解来验证计算结果。结果表明:固定边界情况下初始地应力平衡效果好,但不适用于动力分析;黏弹性边界情况下,初始地应力较大,并会影响动力分析结果;将固定边界情况下的边界节点反力施加在黏弹性边界模型上,既能够实现初始应力场较好地平衡,又不会影响动力分析结果。因此,提出的静、动力问题分析的初始应力场平衡方法合理并且有效,可为后续的岩土工程动力响应分析提供参考。

A method of initial geo-stress equilibrium in static-dynamic analysis

The equilibrium of the initial geo-stress field is particularly important for correct analysis in simulating the confining pressure dependence and contact problems. Therefore, it is a key factor to simulate initial geo-stress field for the following geotechnical engineering dynamic response analysis. Based on the software of ABAQUS, a method of initial geo-stress equilibrium in static-dynamic analysis is proposed in order to realize zero initial vertical displacement in geotechnical engineering analysis and no influence of the initial geo-stress to the subsequent dynamic analysis results. First of all, fixed boundary condition is used and gravity load is applied on the free field, and the reaction forces on boundary nodes are calculated. Secondly, the reaction forces on the boundary nodes are applied on the model in viscoelastic artificial boundary condition, making the initial geo-stress being equilibrium. Finally, dynamic analysis is carried, and the numerical results are verified by theoretical results. The results show that: 1) the initial geo-stress field is well balanced in fixed boundary condition, however, the results are not suitable for the dynamic analysis; 2) the initial geo-stress is too large and will affect the follow-up dynamic analysis in viscoelastic boundary condition; 3) the initial geo-stress is well balanced when applying the reaction forces at boundary nodes from fixed boundary condition on the viscoelastic boundary condition, and the results will not affect the dynamic analysis results. Therefore, the proposed method of initial geo-stress equilibrium in static-dynamic analysis is reasonable and effective, and can provide a theoretical basis of the subsequent analysis for geotechnical engineering dynamic response.