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工程科学与技术:2021,53(2):28-37
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非饱和堆积土边坡降雨-渗流潜蚀耦合过程模拟
(1.四川大学 水利水电学院,四川 成都 610041;2.中国科学院 成都山地灾害与环境研究所,四川 成都 610041;3.成都理工大学 地质灾害防治与地质环境保护国家重点实验室,四川 成都 610059)
Modelling of Coupled Process of Rainfall Infiltration and Internal Erosion Within Unsaturated Deposited Soil Slopes
(1.School of Water Resource & Hydropower, Sichuan Univ., Chengdu 610065, China;2.Inst. of Mountain Hazards and Environment, CAS, Chengdu 610041, China;3.State Key Lab. of Geohazard Prevention and Geoenvironment Protection, Chengdu Univ. of Technol., Chengdu 610059, China)
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投稿时间:2020-01-01    修订日期:2020-05-25
中文摘要: 西部山区的松散堆积土是一种宽级配弱固结土,其内部细小颗粒易随降雨入渗在粗颗粒土骨架间孔隙发生迁移,改变土体水力特性,诱发堆积土边坡降雨失稳。为定量研究降雨作用下堆积体内在的渗流潜蚀耦合演进规律及其斜坡失稳机理,对降雨作用下非饱和堆积土边坡中坡体及孔隙尺寸的细颗粒迁移现象进行了分析概化,并基于多孔介质力学及混合物理论构建了描述非饱和堆积土中细颗粒侵蚀-运移-沉积全过程的渗流潜蚀模型。该模型被植入有限元程序,模拟了降雨作用下1维非饱和堆积土柱内部的渗流潜蚀耦合响应过程,并结合无限边坡模型定量分析了细颗粒迁移引发的土体渗透性、持水性及强度演化对非饱和堆积土边坡降雨入渗过程及稳定性的影响。通过数值模拟,阐释了松散堆积土边坡中细颗粒迁移引发边坡局部土体渗透性变化,形成相对不透水层,诱发浅层坡体失稳现象的内在机理;并指出堆积土中细颗粒的侵蚀流失将减弱土体持水性及抗剪强度,加速边坡内的降雨-渗流潜蚀进程,加速边坡的浅层失稳。鉴于由降雨-渗流潜蚀过程引发的土体渗透性、持水性及强度演化均会对堆积土边坡稳定性造成不利影响,对松散堆积土边坡进行降雨稳定性分析时应充分考虑其内在的细颗粒迁移效应。
Abstract:The loose deposited soils in the mountainous area of western China are usually widely graded and weakly consolidated. Upon rainfall infiltration, the fine particles within these soils are prone to migrate in the pores formed by those coarse particles, which changes the soils’ hydro-mechanical characteristics and destabilizes the slope. In order to study quantitatively the intrinsic evolution law of this rainfall-induced seepage-erosion coupled process within deposited soils and its influence on the slope stability, the fine particle migration phenomena observed within unsaturated deposited soil slopes in both the slope and pore scales were analyzed. Based on the mixture theory, a seepage-erosion coupled model capable of capturing the fine particle migration process within unsaturated soils was proposed. This model was then implemented into a finite element code, and was used to simulate the rainfall-induced seepage-erosion coupled process within a one-dimensional unsaturated soil column. Combined with the infinite slope model, the influences of erosion-induced soil permeability, water retention capacity and strength changes on the rainfall infiltration process as well as on the slope stability were analyzed quantitatively. Through numerical simulation, the intrinsic shallow slope failure mechanism, trigged by the formation of a relatively impermeable layer due to the fine particle migration-induced local change of soil permeability, was explained. It was pointed out that both the water retention capacity and shear strength of the deposited soils will be weakened due to the loss of fine particles, which will accelerate the rainfall-induced seepage-erosion process within the slope, and hence accelerate its failure process. In view of the fact that the changes of soil permeability, water retention capacity and strength due to the seepage-erosion coupled process are all adverse to the slope stability, it is therefore suggested that special attention should be paid to the fine particle migration effect when evaluating the stability of deposited soil slopes under rainfall infiltration.
文章编号:202000001     中图分类号:O241    文献标志码:
基金项目:国家自然科学基金项目(42072315;41702331);国家重点研发计划项目(2017YFC1501000);地质灾害防治与地质环境保护国家重点实验室开放基金项目(SKLGP2018K013)
作者简介:第一作者:雷小芹(1986-),男,博士后,副研究员.研究方向:非饱和土多场耦合模拟.E-mail:leixiaoqin@gmail.com
引用文本:
雷小芹,刘恩龙,何思明,吴礼舟,杨宗佶.非饱和堆积土边坡降雨-渗流潜蚀耦合过程模拟[J].工程科学与技术,2021,53(2):28-37.
LEI Xiaoqin,LIU Enlong,HE Siming,WU Lizhou,YANG Zongji.Modelling of Coupled Process of Rainfall Infiltration and Internal Erosion Within Unsaturated Deposited Soil Slopes[J].Advanced Engineering Sciences,2021,53(2):28-37.