基于流固耦合作用的抽水引起地面沉降计算模型

Calculation Model of Land Subsidence Caused by Pumping Based on Fluid-Solid Coupling

过量开采地下承压水会引起地基土体的变形,进一步导致地面沉降和地裂缝等地质灾害,抽水引起地层的变形过程是土层中孔隙水和土颗粒相互作用的复杂过程.两步法和流固耦合法是计算地面沉降常用的两种思路,它们的适用性各有不同.本文基于理想的地层模型,分别建立两步法计算模型和流固耦合计算模型,利用FLAC3D6.0有限差分软件对模型进行求解,对比分析两类方法计算结果的差异.结果表明流固耦合法符合力学机制,能够更好地反映土体变形的发展过程,但计算时间更长.而两步法适用于稳定流,在渗流达到稳定流时两步法计算的孔压分布和地面沉降能够满足工程精度要求.本文的研究成果为合理选取地面沉降计算方法提供依据.

Excessive exploitation of underground confined water will cause the deformation of foundation soil and further lead to geological disasters such as land subsidence and ground fissures.The deformation caused by pumping is a complex process of interaction between pore water and soil particles in soil layer.The two-step and the fluid-solid coupling methods are two commonly used methods to calculate land subsidence,with different applicability.In this paper,based on the ideal model of the soil layer,the two-step calculation model and the fluid-solid coupling calculation model are established respectively.The finite difference software FLAC3D6.0 is used to solve the model,and the differences between the two methods are analyzed.The results show that the fluid-solid coupling method conforms to the mechanical mechanism and can better reflect the process of soil deformation,but gives rise to longer calculation time.The two-step method is suitable for steady flow.When the seepage flow becomes steady,the pore pressure distribution and land subsidence calculated by the two-step method can meet the engineering precision requirements.The results of this paper provide reference for reasonably selecting the calculation method for land subsidence.