LAND SUBSIDENCE RESEARCH APPROACHES AND ADVENT PROBLEMS
LIU Yi (Shanghai Institute of Geological Survey, Shanghai, 200072, China)
The international and domestic histories of research on land subsidence are summarized, many factors causing land subsidence are introduced, and it is thought an updated generalization about the concept or principle of land subsidence that land subsidence is the loss of surface elevation due to removal of subsurface support. A lot of approaches in domestic land subsidence research are presented, such as monitoring technology, information system, map compilation, prediction and calculation, loss appraisal, and preventive measures. A lot of advent problems in it are also suggested, such as subsidence in the shallow and very soft clay, subsidence in the deep soil layers, subsidence related with engineering, subsidence in Yangtze Delta, and the impact of land subsidence on the height of river dikes nationwide. Finally, it is pointed out that land subsidence will multiply greatly in magnitude and areal extent and become greatly complicated in the east part of China during the high development of urbanization and industrialization in the first half of the 21st century, and careful planning and control of their areas will be necessary to prevent expensive damage as a result of land subsidence.