考虑拉剪耦合作用地震边坡稳定性分析

基于拉剪耦合作用，对Mohr-Coulomb强度准则进行修正。在不同坡高、不同高宽比的边坡底部入射3条经典地震波，对边坡进行动力稳定性分析。首先采用显式迭代子增量法编写考虑拉剪耦合作用的Mohr-Coulomb强度准则子程序，并在边坡模型的截断边界添加黏弹性人工边界、输入等效地震荷载，模拟边坡受到的地震作用；然后以单元分别受到压缩和拉伸作用为例验证子程序的正确性；通过与已有地震边坡的研究结果对比，表明在地震边坡分析中若不考虑材料的拉剪耦合作用，得出的结论偏危险；最后在边坡底部垂直入射3条地震波，分析不同坡高、不同高宽比的边坡在2种强度准则下安全系数的区别。研究结果表明：不同边坡（坡高、高宽比不同）在不同地震波（El-Centro，Kobe，Northridge）作用下的安全系数各不相同，但安全系数都随坡高增加和坡角增大而降低；考虑拉剪耦合作用边坡的安全系数小于不考虑拉剪耦合作用边坡的安全系数，并且其安全系数的变化各有特点；坡高和高宽比的变化影响边坡对地震波频段的响应；分析地震边坡的稳定性，应综合考虑材料的拉剪耦合作用以及边坡高度和高宽比的变化规律。

Stability Analysis of Seismic Slope Considering Tenso-shear Coupling

The Mohr-Coulomb strength criterion was modified based on the tenso-shear coupling. Three classical seismic waves were input on the bottom of slopes with different slope heights and different slope aspect ratios, whilst the dynamic stability analysis of the slope was carried out. First, an explicit iterative sub-increment method was used to formulate the subroutine of Mohr-Coulomb strength criterion in consideration of the tenso-shear coupling. Then in order to simulate the seismic action of the slope, the equivalent seismic load was input on the bottom of model, and the viscoelastic artificial boundaries were also added on the truncated boundary. To verify the correctness of subroutine, a unit subjected to compression and tension was taken as an example. Compared with the existing seismic slope analysis, the results would be dangerous if the tenso-shear coupling was not taken into consideration. Three seismic waves were vertically input on the bottom of slope. The difference of safety factors of slopes with different slope heights and different aspect-ratios were analyzed on the basis of two strength criteria. The results show that:slopes with different shapes (slope heights and slope aspect ratios) which under different seismic waves (El-Centro, Kobe and Northridge) have different safety factors. However, the slope safety factor decreases with the increase of slope heights and slope angles. Safety factors considering tenso-shear coupling are lower than that without considering tenso-shear coupling. And the variation of safety factors has its own characteristics. The slope response of seismic wave band is influenced by the change of heights and aspect ratios. Therefore, the tenso-shear coupling of geomaterials as well as changing laws of different slope heights and different slope aspect ratios should be considered when analyzing the stability of seismic slope.