流固耦合的多元结构深厚覆盖层透水地基的力学特性

发布时间：2018-04-15 19:40

本文选题：深厚覆盖层 + 粉细砂层　；参考：《土木建筑与环境工程》2017年03期

【摘要】：深厚覆盖层多元结构坝基在渗流过程中各土层力学差异明显,分析时关注的具体问题也不尽相同,需要深入研究。基于比奥固结理论,考虑土体的非线性流变以及土体固结变形过程中孔隙度、渗透系数、弹性模量及泊松比的变化;借助ADINA流固耦合模块来模拟西藏达嘎水电站坝基渗流场与应力场耦合过程,分析各层力学特性及相互作用。研究表明,透水性较强的表层土体是渗流主要通道,也是渗流进出区和沉降变形体现区,应在上游采取措施提高其压缩模量,下游区域增设反滤层和排水设施;坝基中的粉细砂层是坝基沉降的主要原因,对坝基沉降起主导作用,同时应注意其液化特性对坝基的不利影响;坝基中的承压含水土层对下游上部结构产生向上顶托力,若位置较深,则破坏性较小;坝基深部土层对整个坝基的渗流破坏影响较小,但对沉降和渗流量的影响不可忽视;表层砂卵砾石层和粉细砂层的渗透系数相差较小时,土层间不会发生接触冲刷。此外,还发现坝基孔隙水压力在快速衰减阶段被消散,期间土体固结较快。垂直防渗墙能有效降低渗透坡降和渗流量,将坝基沉降变形控制在防渗墙上游区域,但上游坝基变形对防渗墙产生较大的水平推力,应加大防渗墙尺寸或者采用辅助渗控措施。
[Abstract]:In the seepage process of deep overburden multicomponent structure dam foundation, the mechanical difference of each soil layer is obvious, and the specific problems concerned in the analysis are not the same, so it is necessary to study deeply.Based on Biot consolidation theory, the nonlinear rheology of soil and the changes of porosity, permeability, elastic modulus and Poisson's ratio during consolidation and deformation are considered.The coupling process of seepage field and stress field of dam foundation of Daga Hydropower Station in Tibet is simulated by ADINA fluid-structure coupling module. The mechanical characteristics and interaction of each layer are analyzed.The study shows that the surface soil with strong permeability is the main channel of seepage flow, the seepage flow in and out area and the settlement and deformation area. Measures should be taken to increase the compression modulus of the soil in the upstream, and the filter layer and drainage facilities should be added in the downstream area.The silty sand layer in the dam foundation is the main reason for the settlement of the dam foundation, which plays a leading role in the settlement of the dam foundation. At the same time, attention should be paid to the adverse effect of its liquefaction characteristics on the dam foundation.If the position is deeper, it will be less destructive, the deep soil layer of the dam will have little effect on the seepage failure of the whole dam foundation, but the influence on the settlement and seepage discharge can not be ignored, and the permeability coefficient of the surface sand gravel layer and silty sand layer will be smaller.There will be no contact erosion between soil layers.In addition, it is found that the pore water pressure of the dam foundation dissipates at the stage of rapid attenuation, and the consolidation of the soil is faster.Vertical impermeable wall can effectively reduce the seepage gradient and seepage discharge, and control the settlement deformation of dam foundation in the upstream area of the cutoff wall. However, the dam foundation deformation in the upper reaches has a large horizontal thrust on the impervious wall, so the size of the impermeable wall should be increased or the auxiliary seepage control measures should be adopted.
【作者单位】：重庆三峡学院土木工程学院;石河子大学水利建筑工程学院;武汉大学水利水电学院;
【基金】：国家自然科学基金(51309262) 重庆市科委基础与前沿研究计划(cstc2015jcyjA1204、cstc2015jcyjA00022)~~
【分类号】：TV223.4

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