摘要
细粒迁移机制是理解砂砾土渗流侵蚀过程的基础与关键,对研究砂砾土斜坡雨水侵蚀过程的细观致灾机制具有重要意义。目前其运移模式及运移状态发生转变的临界条件并不清晰,不同物理水力条件下的细粒运动类型有所不同。为掌握砂砾土侵蚀过程中细粒的整体运动类型及其发生改变的临界条件,采用可视圆柱入渗试验和离散元数值模拟,分析了细粒迁移的影响因素和内部机理。结果表明:(1)细粒迁移受级配和水力梯度影响显著,而受初始孔隙率影响不显著,且级配的影响大于水力梯度;(2)水力作用下细粒整体运动状态可分为沉积和滤通2种模式,内部结构不稳定的砂砾土细粒运动处于滤通状态,内部结构稳定和稳定性过渡型砂砾土随水力梯度升高细粒的运动状态从整体沉积转变为整体滤通;i=3.4-(3)细粒运动状态在粒径比和水力梯度共同作用下存在明显界限,最终得到细粒沉积-滤通转变的临界条件为0.12e(D15/d85)/1.5。研究可为砂砾土斜坡渗蚀失稳防护提供理论指导。
The mechanism of fine grains migration is the basis and key to understand the seepage erosion process of gravel soil,which is significance to study the disaster-caused mesomechanism of rain erosion process on sandy gravel slopes.However,the migration mode and critical condition for the transition of migration state are unclear.The migration types of fine grains differ from different physical and hydraulic conditions.To reveal the overall movement characteristics of fine grains and the critical conditions for the change of their motion state during the process of gravel soil erosion,this study adopted the visual cylindrical infiltration test and discrete element numerical simulation to analyze the influencing factors and mechanism of the fine grains migration,deposition,and self-dredging.The results show that:(1)the migration of fine grains is significantly affected by the gradation and hydraulic gradient but not by the initial porosity.The gradation has a greater effect than the hydraulic gradient.(2)The overall motion of fine grains under hydraulic forces can be divided into two states:deposition and self-dredging.The fine grains of gravel soil with unstable internal structure are in the self-dredging state,and that with stable and transitional internal structure will change from deposition to self-dredging with the increase of hydraulic gradient.(3)The motion state of fine grains has an obvious boundary under the combined effects of grain size ratio and hydraulic gradient,and the critical condition for fine grains transition from deposition to self-dredging is i=3.4-0.12e(D15/d85)/1.5obtained to be.
作者
董辉
谭凤鸣
程子华
高乾丰
任佳展
DONG Hui;TAN Fengming;CHENG Zihua;GAO Qianfeng;REN Jiazhan(Hunan Key Laboratory of Geomechanics and Engineering Safety,Xiangtan University,Xiangtan,Hunan411105,China;School of Traffic&Transportation Engineering,Changsha University of Science&Technology,Changsha,Hunan 410114,China)
出处
《水文地质工程地质》
CSCD
北大核心
2024年第1期69-81,共13页
Hydrogeology & Engineering Geology
基金
国家自然科学基金项目(42272304)
湖南省教育厅科学研究项目(22C0046)。
关键词
砂砾土
渗流侵蚀
细粒迁移
运移模式
临界条件
gravel soil
seepage erosion
fine grains migration
migration mode
critical condition
