Sensitivity analysis of related parameters in simulation of land subsidence and ground fissures caused by groundwater exploitation

Abstract

Hydraulic and mechanical parameters are very important in the calculation of models of land subsidence and ground fissures caused by groundwater exploitation. To investigate the degree of influence of these parameters on calculation of models of land subsidence and ground fissures, Morris’ global sensitivity analysis, combined with local sensitivity analysis, was applied. The accuracy of soil parameter sensitivity analysis is related closely to selection of the calculation model used. Based on Biot’s consolidation theory, and combined with the nonlinear rheological theory of soil, a three-dimensional full coupling mathematic model was established to simulate land subsidence and ground fissures, in which the constitutive relation in Biot’s consolidation theory was extended to viscoelastic plasticity. The dynamic relationships of soil parameters (porosity, permeability coefficient, parameters of soil deformation) accompanied by changes in the stress field were also considered. Consequently, this model conforms to actual conditions in the field. Nantong, Jiangsu Province in China, was selected to simulate and calculate land subsidence and ground fissures using this model, and the soil parameters’ sensitivities were analyzed. The results showed that elastic modulus, E, cohesion, c, and the specific weight of soil, $$ \lambda $$ , have a significant influence on land subsidence and ground fissures, with the influence of the friction angle, $$ \varphi $$ , on land subsidence, and of Poisson’s ratio, $$ \nu$$ , on ground fissures taking second place. These five parameters are thus of major concern in the simulation of land subsidence and ground fissures.