Three-dimensional modeling of land subsidence in Shanghai, China
S. Ye, Y. Luo, J. Wu
School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
X. Yan, H. Wang, X. Jiao
Key Laboratory of Land Subsidence Monitoring and Prevention,
Ministry of Land and Resources, Shanghai Institute of Geological
Survey, Shangha, China
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
Shanghai, in China, has experienced two periods of
rapid land subsidence mainly caused by groundwater exploitation
related to economic and population growth. The first
period occurred during 1956-1965 and was characterized by
an average land subsidence rate of 83 mm/yr, and the second
period occurred during 1990-1998 with an average subsidence
rate of 16 mm/yr. Owing to the establishment of monitoring
networks for groundwater levels and land subsidence,
a valuable dataset has been collected since the 1960s and used
to develop regional land subsidence models applied to manage
groundwater resources and mitigate land subsidence. The previous
geomechanical modeling approaches to simulate land
subsidence were based on one-dimensional (1D) vertical
stress and deformation. In this study, a numerical model of
land subsidence is developed to simulate explicitly coupled
three-dimensional (3D) groundwater flow and 3D aquifersystem
displacements in downtown Shanghai from 30
December 1979 to 30 December 1995. The model is calibrated
using piezometric, geodetic-leveling, and borehole
extensometer measurements made during the 16-year simulation
period. The 3D model satisfactorily reproduces the measured
piezometric and deformation observations. For the first
time, the capability exists to provide some preliminary estimations
on the horizontal displacement field associated with the
well-known land subsidence in Shanghai and for which no
measurements are available. The simulated horizontal displacements
peak at 11 mm, i.e. less than 10% of the simulated
maximum land subsidence, and seems too small to seriously
damage infrastructure such as the subways (metro lines) in the
center area of Shanghai.
