基于Modflow的地面沉降与地下水流耦合模型程序实现

Realization of Land Subsidence and Groundwater Flow Coupling Model Based on Modflow

在总结前人地下水流模型与地面沉降模型基础上,考虑孔隙率与渗透系数变化之间的相关性,建立了地下水流与地面沉降耦合模型.通过改进国际上通用的Modflow源程序,实现两者之间耦合作用,并模拟这一过程.通过典型算例对改进的程序进行验证,结果表明:考虑参数变化的沉降速率变化较快,其主要原因在于,抽取地下水引起水位下降,造成土体压缩、孔隙度和渗透率降低.渗透率降低使得含水层产生了水力梯度和渗透力,可能会导致地面沉降加速下沉.因此,非线性水力特性是流固耦合的交互作用基础,不应该被忽视.该结果进一步验证了改进的程序可以模拟耦合过程,研究成果可为地面沉降与地下水流动耦合模拟研究提供技术支持.

On the basis of summarizing predecessors' groundwater model and land subsidence model,the water flow and land subsidence coupling model has been built on considering the correlation between porosity and permeability coefficient. In order to realize and simulate the coupling process between water flow and land subsidence,the source code of Modflow that is a common international program has been improved. In order to verify the modified program,a typical example has been established. The results show that the subsidence rate is faster than conventional groundwater theory when the hydraulic properties changes are considered in the coupled model. The reason is perhaps that the water level decline due to groundwater withdrawal induces the soil compression and the porosity and permeability decrease. Decrease of permeability produces hydraulic gradient and seepage forces that may result in accelerated subsidence. Therefore,the effect of the nonlinear hydraulic properties is an interactive process of pore water pressure and soil consolidation deformation and should not be ignored. Furthermore,the result can prove that the modified program can simulate the coupling process. This research can offer technical support for land subsidence and water flow coupling simulation.