考虑参数旋转各向异性空间变异性的边坡大变形概率分析

Probabilistic Analysis of Large Slope Deformation Considering Soil Spatial Variability with Rotated Anisotropy

为揭示土体参数旋转各向异性空间变异性对边坡大变形特征的影响规律,将土体不排水抗剪强度参数模拟为旋转各向异性随机场,提出采用多重响应面法对随机场样本进行边坡稳定性安全系数高效求解和升序排列,进而使用随机物质点法按序模拟随机场样本的边坡大变形过程.以一饱和不排水粘土边坡为例,研究了旋转各向异性随机场的旋转角度β和弱主方向自相关长度θ2对边坡大变形特征和破坏模式的影响.结果表明:提出的基于多重响应面的随机物质点方法可以高效开展边坡大变形概率分析;β和θ2对边坡大变形特征和破坏模式均有显著影响;边坡大变形破坏的影响距离、滑动距离和滑动体积的平均值与标准差均随θ2的增加而增加;边坡大变形过程中可能产生4种破坏模式,其中深层滑动和渐进式滑动为该边坡模型的主要概率失稳模式.因此,提出的方法为边坡大变形概率分析提供了一条有效途径,考虑参数旋转各向异性空间变异性的边坡大变形概率分析对准确评估边坡失稳风险具有一定的理论参考意义.

To explore the influence of spatial variability of soil parameters with rotated anisotropy on probabilistic large slope deformation characteristics,a multiple response surface-based random material point method is proposed in this study.First,random field theory is employed to simulate the spatial variability of soil parameters with rotated anisotropy.Then,the multiple response surface method is used to evaluate the factor of safety(FS)of each random field sample,based on which the FSs for all random field samples are sorted efficiently in an ascending order.Finally,the random material point method is used to sequentially simulate the large deformation features of a slope for the failed samples with the FS at less than 1.An undrained clay slope is taken as the illustrative example,where the undrained shear strength of the soil is simulated as a rotated anisotropic random field.The effect of the rotational angleβand the autocorrelation lengthθ2 in the minor principal direction of the rotated anisotropic random field on the large deformation features and failure modes of the slope are systematically studied.The results show that the proposed method can be efficiently conducted for probabilistic analysis of large slope deformation.Bothβandθ2 have significant effects on large slope deformation features and failure modes.In terms of large deformation features,the mean and standard deviation of the influence distance,sliding distance,and sliding volume increase with the increase ofθ2.There might be four failure modes when considering the rotated anisotropic spatial variability of the undrained strength of the slope,among which the deep sliding mechanism and progressive failure are the two main probabilistic failure modes.Therefore,the proposed method provides an effective way for the probabilistic large slope deformation analysis as well as a good theoretical reference for an accurate risk assessment of slope stability.