Modeling visco-elastic-plastic deformation of soil with modified Merchant model

Eighty-four to ninety-eight percent of land subsidence in Shanghai City is caused by the visco-elastic-plastic deformation of sediments. Numerical experiments are done on the sediments with visco-elastic-plastic deformation in Shanghai to verify the modified Merchant model (MM model) and land subsidence model based on the modified Merchant (LS-MM) model. There are two advantages of the MM model and the LS-MM model. One is that only a few parameters are involved. There are three parameters in the MM model and four parameters in the LS-MM model. The other one is that both models can describe elastic, elastic-plastic and visco-elastic deformation in addition to visco-elastic-plastic deformation. The corresponding models are developed by setting proper values of the three parameters of mu, alpha (1) and alpha (2). The two advantages make the LS-MM model flexible and applicable to the simulation of the large regional land subsidence with visco-elastic-plastic deformation and other different kinds of deformation. The results can be improved by variable parameters, especially specific storage.