Characterization of earth fissures in South Jiangsu, China
S. Ye, Y. Wang, J. Wu
School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
J. Yu, X. Gong, G. Wang
Key Laboratory of Land Subsidence Monitoring and Prevention,
Ministry of Land and Resources, Shanghai Institute of Geological
Survey, Shangha, China
The Suzhou-Wuxi-Changzhou (known as "Su-Xi-Chang") area, located in the southern part of
Jiangsu Province, China, experienced serious land subsidence caused by overly exploitation of groundwater.
The largest cumulative land subsidence has reached 3 m. With the rapid progress of land subsidence since the
late 1980s, more than 20 earth fissures developed in Su-Xi-Chang area, although no pre-existing faults have been
detected in the surroundings. The mechanisms of earth fissure generation associated with excessive
groundwater pumping are: (i) differential land subsidence, (ii) differences in the thickness of
the aquifer system, and (iii)
bedrock ridges and cliffs at relatively shallow depths. In this study, the Guangming Village Earth Fissures in Wuxi
area are selected as a case study to discuss in details the mechanisms of fissure generation. Aquifer exploitation
resulted in a drop of groundwater head at a rate of 5-6 m yr-1
in the 1990s, with a cumulative drawdown of
40 m. The first earth fissure at Guangming Village was observed in 1998. The earth fissures, which developed
in a zone characterized by a cumulative land subsidence of approximately 800 mm, are located at the flank of a
main subsidence bowl with differential subsidence ranging from 0 to 1600 mm in 2001. The maximum differential
subsidence rate amounts to 5 mm yr-1
between the two sides of the fissures. The fissure openings range
from 30 to 80 mm, with a cumulative length of 1000 m. Depth of bed rock changes from 60 to 140 m across the
earth fissure. The causes of earth fissure generation at Guangming Village includes a decrease in groundwater
levels, differences in the thickness of aquifer system, shallow depths of bedrock ridges and cliffs, and subsequent
differential land subsidence.
