基于变渗透系数的深基坑单井抽水沉降研究

摘要

Groundwater pumping is an important factor for surface settlement.Based on the Konzeny-Carman seepage model of elastic porous medium,a modified model with changeable permeability coefficient using soil strain is established through consideration of soil internal changes of physical and mechanical properties in the process of the strata deformation due to water pumping.A concept of permeability influential coefficient is then introduced. Using the multi-physical field coupling finite element software COMSOL,a three-dimensional model is built to analyze the variation law among soil settlement and permeability coefficient and influential coefficient.The model is based on the completely coupled method of Darcy seepage and elastic porous medium,and compares the measured settlement data with calculated values.The results show that the calculated values using the modified changeable permeability coefficient model agree fairly well with the actual measured values.This model can better reflect the process of sedimentation causing by pumping.%地下水抽采是造成地表沉降的重要原因。基于弹性多孔隙介质Konzeny-Carman渗透模型，考虑地层在抽水过程中变形导致土层内部物理力学性质的改变，建立了基于土体应变的变渗透系数模型，并引入了渗透影响系数概念。运用有限元多物理场耦合软件COMSOL建立模型，采用Darcy渗流模式与弹性多孔隙介质完全耦合方法，研究了抽水过程中地层沉降量与渗透影响系数以及渗透系数的变化规律，并与实测沉降值进行对比。研究表明，采用考虑土体变形的变渗透系数模型所计算的沉降量与实测沉降变形较好地吻合，该模型能更好地反映抽水过程中沉降动态过程。