Computation of Land Subsidence in Shanghai

Computations of land subsidence in Shanghai are carried out by employing the basic one-dimensional consolidation equation and the Laplace transformation. They are based on the inferences: （1） validity of the classical consolidation theory; （2） validity of superposition theorem of boundary water level conditions in aquifers; and （3） adaptability of bi-linear model under cyclic loading. Analysis shows that the phenomena of land subsidence can be well interpreted by stress redistribution and its consequent deformation occurred in the soil layer as a result of subterranean pumping. The comparisons from 1965-1978 between the computed and actually measured data on hydrostatic excess pressures and deformations are good. This analysis also provides a sound basis for suggesting groundwater recharging as an effective means to control the subsidence.