降压回灌作用下黏土的渗透特性试验研究

发布时间：2018-04-13 14:22

本文选题：黏土 + 降压回灌　；参考：《岩土工程学报》2015年S1期

【摘要】：为控制深基坑降水和承压水降压引起的土体沉降问题,通常采用坑外回灌措施,而软黏土渗透特性在抽水回灌过程中出现的变化会影响回灌效果和土体变形特性。采用GDS三轴试验仪对上海黏土土样进行室内降压回灌模拟试验,研究降压回灌的渗流作用对黏土渗透特性的影响规律。试验通过设置围压和初始孔压来控制土样应力水平,利用反压变化模拟孔隙水的降压和回灌过程,测试土样的渗流变化与变形,从而分析土样孔隙比、渗透系数等参数的变化规律。研究发现,渗透系数在降压阶段因孔隙比减小而降低,并存在非线性关系;土体孔隙比在回灌阶段逐渐增大,但渗透系数因堵塞效应而呈现进一步降低趋势;可用e lgk拟合曲线建立孔隙比与渗透系数之间的非线性关系。
[Abstract]:In order to control the settlement of soil caused by dewatering of deep foundation pit and pressure reduction of confined water, the measures of recharge outside the pit are usually adopted, while the change of permeability characteristics of soft clay in the process of pumping and recharging will affect the effect of recharge and the deformation of soil.In this paper, GDS triaxial test instrument was used to simulate the pressure reduction and recharge of Shanghai clay samples, and the influence of pressure and recharge seepage on the permeability of clay was studied.The stress level of soil sample is controlled by setting confining pressure and initial pore pressure, and the depressurization and recharge process of pore water are simulated by reverse pressure change, the seepage change and deformation of soil sample are measured, and the porosity ratio of soil sample is analyzed.The variation of permeability coefficient and other parameters.It is found that the permeability coefficient decreases with the decrease of porosity ratio and has a nonlinear relationship at the stage of pressure reduction, and the porosity ratio of soil increases gradually in the stage of recharge, but the permeability coefficient decreases further because of clogging effect.The nonlinear relationship between porosity and permeability coefficient can be established by e lgk fitting curve.
【作者单位】：上海交通大学土木工程系;
【基金】：国家自然科学基金项目(41330633) 国土资源部公益性行业科研专项经费项目(201311045-03)
【分类号】：TU411

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