Coupling simulation of groundwater seepage and land subsidence

In order to accurately simulate land subsidence caused by seepage field as a result of groundwater exploitation and stress field, two models are established in this study: one is groundwater seepage and land subsidence coupling numerical simulation model of the three-dimensional seepage of groundwater and one-dimensional vertical consolidation in light of Terzaghi effective stress principle; and the other is three-dimensional coupling model of groundwater seepage and land subsidence based on the Biot's consolidation theory combined with the nonlinear rheological theory of soil, extending the constitutive relation in Biot's consolidation theory to viscoelastic plasticity, taking into consideration of the dynamic change relationship of mechanical parameters and hydraulic parameters. The comparison and analysis show that the changing tendency of land subsidence calculated by groundwater seepage and land subsidence coupling numerical simulation model of the three-dimensional seepage of groundwater and one-dimensional vertical consolidation is the same as that of water level variation. When the water level falls back to the initial water level, total subsidence is 0. Land subsidence calculated by Biot's three-dimensional full coupling model falls behind of water level change. When the water level falls back to the initial water level, soil does not rebound to initial 0 subsidence state. There exists permanent remain of subsidence. In aspect of parameter change, porosity, hydraulic conductivity and Poisson's ratio have the tendency of decreasing first and then increasing. Modulus of elasticity has the tendency of decreasing first and then increasing. But these parameter values tend to be stable, corresponding to land subsidence variation.