降雨入渗条件下双层非饱和土边坡渐进性破坏数值分析  

Numerical analysis of progressive failure of double-layered unsaturated slope due to rainfall infiltration

作　　者：洪心怡 刘志强[1] 胡春洋 熊勇林 HONG Xinyi;LIU Zhiqiang;HU Chunyang;XIONG Yonglin(School of Civil and Environmental Engineering and Geography Science,Ningbo University,Ningbo 315211,China)

机构地区：[1]宁波大学土木工程与地理环境学院,浙江宁波315211

出　　处：《自然灾害学报》2023年第2期71-80,共10页Journal of Natural Disasters

基　　金：浙江省自然科学基金项目(LY19E080012);宁波市自然科学基金项目(2018A610230)。

摘　　要：为了研究降雨入渗引起的双层非饱和土边坡的破坏机理,提出了渗透变形水-土-气三相耦合的有限元数值分析方法。计算程序中通过采用合理的非饱和土弹塑性本构模型,使其可描述双层非饱和土边坡在降雨入渗时的渗透-变形耦合力学特性变化,进而更加清晰明了地阐述非饱和土边坡的破坏机理。以2层不同湿密度的非饱和砂土边坡的模型实验作为研究对象,采用所提出的数值计算方法对不同降雨强度(50、100 mm/h)与双层坡角(59°和68.3°)等4个工况进行了数值模拟分析。与试验结果对比可知,数值模拟结果可以很好地再现试验观测现象,包括不同工况下的孔隙水压力变化、破坏时间。计算结果表明:1)由于2个土层的透水系数有所差异,水在2个土层之间的水分迁移较为缓慢。2)坡角越小(59°)或者降雨强度越小(50 mm/h),边坡破坏所需要的时间越长。3)在降雨过程中塑性破坏是从边坡左侧的坡趾附近开始,逐渐延伸至坡顶,最后形成一条贯穿整个边坡的塑性剪切带。4)边坡左侧的土体整体沿着滑动带向下滑动。在降雨强度较大(100 mm/h)的情况下,边坡滑动的规模相对较小。In order to study the failure mechanism of double-layered unsaturated slope caused by rainfall infiltration,a finite element numerical analysis method of water-soil-air three-phase coupling of infiltration-deformation was proposed.In the program,a reasonable elasto-plastic constitutive model of unsaturated soil was adopted to describe the mechanical behaviour of infiltration-deformation coupling of double-layered unsaturated slope during rainfall infiltration.A model test of unsaturated sand slope with two different wet densities was regarded as a research object,and four working conditions of different rainfall intensity(50 mm/h and 100 mm/h)and slope angle(59°and 68.3°)were used by proposed numerical method.By comparing with the test results,the numerical simulation results can reproduce experimental observation phenomena well,including pore water pressure change and failure time under different working conditions.The calculation results show that:1)Rainfall migration between two layers soil is slow due to the different permeability coefficients of two layers soil.2)The smaller the slope angle(59°)or the rainfall intensity(50 mm/h),the longer the time required of slope destruction.3)Plastic failure starts from the left slope toe and it gradually extends to the slope top during rainfall process.Finally,the plastic shear band runs through the entire slope.4)The left soil slides along the plastic shear band on the whole.In the case of heavy rainfall intensity(100 mm/h),the sliding scale of slope is relatively small.

关 键 词：失稳破坏 有限元数值计算 非饱和土边坡 土-水-气三相耦合 降雨入渗 

分 类 号：TU413[建筑科学—岩土工程] X43[建筑科学—土工工程]