Abstract: By adopting Biot’s consolidation theory and the contact analysis of discontinuity surfaces, a two-dimensional calculation model containing two ground fissures is set up based on detailed groundwater and stratigraphic data in Xi’an. By using this model, the pumping-induced land subsidence under preexisting fault situation is simulated as much detailed as possible. Combining the land subsidence monitoring, the space distribution pattern is analyzed. The results indicate that the amount of compression of the soil deposit 100-300 m beneath contributes to the main settlement. The initiation of the ground fissures is not only for the differential subsidence caused by thickness change of soil deposit, but also the presence of fault. Because of the existing of the normal fault, the displacement of hanging wall is magnified, while the displacement is reduced during the ground subsidence. The reverse effect makes the scarp become larger and larger; so that the ground fissure hazards become more and more serious. The research results are benefit to further understanding the mechanisms of ground fissures, also can play some roles for predicting its development.

Key words: land subsidence, ground fissures, monitoring, layerwise mark, numerical simulation