基于物质点法的土体强度对边坡失稳滑动距离影响研究

Impacts Analysis of Soil Strength on Sliding Distance of Unstable Slope Based on Material Point Method

滑坡滑动距离是衡量边坡失稳致灾程度的重要指标之一。基于Drucker-Prager弹塑性本构模型,应用物质点法研究了土体强度对失稳边坡滑动距离的影响。首先,通过干燥铝棒坍塌试验和黏土边坡大变形算例验证物质点法程序,分析了离散物质点数量对边坡失稳模拟结果精度的影响。在此基础上,进一步研究不同坡角下黏聚力和内摩擦角对失稳边坡滑动距离的影响规律。结果表明:相邻物质点间距取0.4 m进行数值模拟能够保证结果的精度且计算效率高;随着黏聚力、内摩擦角的增大,滑动距离呈逐渐减小的趋势;边坡失稳过程是以坡脚处产生较大塑性应变开始,塑性区域不断扩展至坡顶形成贯穿的滑裂带,进而整体失稳。物质点法能够再现边坡失稳的整个过程,有助于深入理解滑坡的致灾机理进而为边坡加固措施设计提供可靠依据。

The sliding distance is one of the important indexes to measure the disaster degree of slope instability.Based on the Drucker-Prager elastoplastic constitutive model,the influence of soil strength on sliding distance of unstable slope was analyzed by material point method. Firstly,the material point method program was verified by collapsing test of dry aluminium bars and large deformation example of clay slope,and the influence of number of discrete material points on the accuracy of slope instability simulation results was analyzed. The influence of cohesion and internal friction angle on sliding distance of unstable slope was determined. The results show that the numerical simulation with the distance of 0. 4 m between adjacent material points can ensure the accuracy of the results and the calculation efficiency is high. With the increase of cohesion and internal friction angle,the sliding distance decreases gradually.The instability process of slope starts with the large plastic strain at the toe of the slope,and the plastic area expands to the top of the slope to form a penetrating sliding crack zone,and then the overall instability is achieved. The material point method can reproduce the whole process of slope instability,which can help to understand the disaster mechanism of landslide and provide reliable basis for the design of slope reinforcement measures.