弹塑性变形条件下抽水引起的地面沉降三维数值模拟

摘要

基于部分耦合原理,采用TOUGH2和FLAC3D建立抽水引起的三维地面沉降弹塑性模型,模型中综合考虑土体的弹塑性变形特征、渗流-应力的双向耦合作用以及参数的非线性,探讨了持续抽水和脉冲抽水两种抽水过程中地面沉降发展演化过程.研究结果表明:(1)集中抽水停止后地面沉降会发生回弹,抽水中心沉降量不断减小.由于水平方向存在水力梯度,地下水继续向地下水位漏斗中心渗流从而导致沉降漏斗的范围仍继续扩大;(2)脉冲抽水导致土体的孔隙水压力、渗透系数以及沉降量均呈周期性波动变化,地面沉降会局部回弹,但总体仍随着抽水的持续,沉降量不断增加;(3)在抽水量相同前提下,对比持续抽水与脉冲抽水两种方式引发的塑形沉降量可知,抽水速率小、脉冲式多次开采导致的塑性沉降量较小,持续抽水的抽水速率越小、脉冲抽水间隔越短越有利于控制地面沉降.研究成果为地面沉降数值模拟提供了一种新方法,其中算例研究能为抽水条件下地面沉降的控制提供参考.%In this paper,TOUGH2 and FLAC3D are sequentially executed and linked to solve partial coupled three-dimensional land subsidence model,which considers the elastic-plastic deformation behavior,coupled hydro-mechanical effect and the varying nonlinear parameters.The evolution of land subsidence due to constant pumping and pulse pumping is compared to study the strategy of land subsidence control.Results show that:(1) Settlements rebound near the pumping well when stopping pumping,but the land subsidence cone continues enlarge.The plastic deformation can't recover;(2) Pulse pumping results in fluctuation of the pore pressure,parameters and deformation,but they still dwindle globally;(3) The constant pumping strategy was compared with the pulse pumping with the same pumpage.Under this condition,the plastic deformation decrease with lower pumping rate and small intervals.This is mainly due to the fact that the groundwater level can recover rapidly with lower pumping rate and small intervals.This research provides a new method to simulate land subsidence,and the case study would contribute to the control of land subsidence.