Peridynamics modelling of earth fissures associated to aquifer exploitation and pre-existing normal faults with applications to Beijing, China

Land subsidence and earth fissures are geological hazards caused by groundwater withdrawal and influenced by a variety of factors, including complex geological structures and heterogeneous lithological sequences. These settings characterize the mechanism and evolution of these processes, whose understanding is important for both risk management and sustainable development of subsurface resources. To model the progression of land subsidence into earth fissures presents a notable challenge when applying classic continuum mechanics theory based on differential equations. This challenge arises from the intrinsic contradiction between the continuous nature of the theoretical framework and the actual discontinuous reality observed in earth fissures. Conversely, peridynamics offers a solution by employing equilibrium equation based on an integral formulation that is mathematically compatible with any discontinuity. This study develops an efficient procedure based on ordinary state-based peridynamics theory to simulate the evolution of land subsidence into earth fissures. The modified Coulomb failure criterion is applied to identify the locations and timing of fissure development, as well as their geometric characteristics, such as length, depth, offset, and opening. This approach is applied to the Chaobai River alluvial fan in Beijing, China, an area where numerous earth fissures have emerged over the past decades, posing threats to structures and infrastructures. The Gaoliying earth fissures are the most severe in Beijing and are distributed along the pre-existing Huangzhuang-Gaoliying normal fault system. InSAR has revealed an uneven land subsidence on the hanging wall and footwall of the fault, with more severe subsidence occurring on the latter. This complex deformation pattern has contributed to a poor understanding of the mechanism governing the formation and evolution of these earth fissures. This study provides an effective approach toward comprehending the generation and propagation of earth fissures induced by aquifer exploitation in this area and in other faulted basins worldwide.