Simulating earth deformation evolution caused by groundwater pumping through ordinary state-based Peridynamics method

Abstract

Earth deformation including land subsidence and the related earth fissures caused by the over-exploitation of groundwater resources is threatening countries all over the World. At present, the simulation of earth deformation of aquifer system is mainly based on continuum and contact mechanics. These approaches lead to two main challenges, i.e. the need of knowing the location of possible earth fissures in advance and using meshes that must be adjusted during the rupture propagation. Here, ordinary state-based Peridynamics method is firstly introduced to simulate the evolution of continuous and discontinuous earth deformation due to groundwater withdrawal. A failure criteria accounting for shear and tensile strain simultaneously is proposed. The approach is used to simulate the evolution of land subsidence and earth fissures in compressible sedimentary soils with buried rigid ridges. Two case studies are reproduced: one is a test carried out in laboratory and the other one concerns Guangming village, Yangtze River delta. In both cases, the presence of a shallow buried bedrock crossing the alluvial deposits is responsible for the initiation and growth of earth fissure that a satisfactory captured by the model. For the lab experiment, a 0.1 m deep fissure appearing above the rocky tip is computed. In Guangming village area, results show that some small fissure groups were initiated. Then, three main earth fissures developed rapidly with the maximum depth of 32.5 m. This study proposes a consistency modelling framework to simulate continuum earth deformation and discontinuous fissures due to groundwater withdrawal in specific geological settings, and supply a reliable scientific tool for early warning of this geo-hazard.