基于全局极限响应面的预应力锚索加固边坡抗震可靠度分析

Seismic reliability analysis of slope reinforced with prestressed anchor cable based on global limit response surface

通过反向采用极向条分的极限分析上限法获取临界强度参数对,拟合得到预应力锚索边坡对应的抗震全局极限响应面方程,将其作为内核函数使用Monte Carlo模拟得到特定地震烈度下的预应力锚索加固边坡的失稳概率和可靠度指标,避免直接使用极限分析上限法而造成的抽样和寻优算法的冗余嵌套。将该方法应用于预应力锚索加固边坡算例中,并将抗震全局极限响应面与基于"均值最不利滑动面"的极限响应面进行了对比,结果表明全局极限滑动面所得失稳概率较大,特定滑面的极限响应面法偏于不安全。进一步分析了锚索参数对边坡抗震失稳概率的影响以及失稳概率与可靠度的关系曲线,表明该方法很好地兼顾了变异参数空间的全局性以及计算的高效性,可以为基于可靠度的预应力锚索边坡抗震设计提供理论参考。

The critical strength parameter pairs are calculated by reversely using the upper-bound limit analysis with polar slice method, which are treated as fitting data to obtain the seismic global limit response surface. The seismic global limit response surface is then regarded as kernel function and applied to Monte Carlo simulation to obtain the seismic failure probability and corresponding reliability index of reinforced slope with prestressed anchor cable, which avoided redundant and nested calculations by directly using the upper-bound limit analysis. In addition, this method is applied to a typical slope case which is reinforced with prestressed anchor cable. The results of limit response surface based on 'the most adverse sliding surface with mean parameter' is calculated and compared with ones of global limit response surface. The results show that the failure probability of global limit response surface is larger than the other one; therefore, the method based on specific limit response surfaces may tend to be unsafe. Moreover, the influence of anchor parameters on seismic failure probability and the relationship curve between failure probability and reliability index are analyzed respectively. This method gives consideration to both the global variation of parameter space and efficiency of computation, so as to provide theory references for the seismic design of reinforced slope with prestressed anchor cable based on reliability index.