Abstract Construction of urban metro is becoming a hot issue in China，therefore，the prediction and control of ground subsidence caused by metro construction need special attention. Now，the centrifugal test is widely used to study the ground subsidence caused by metro excavation，but the factors that cause the ground subsidence are not the same in different strata. Because loess strata have the characteristics of seismic subsidence deformation and collapse，it is more difficult for construction of urban metro in loess area. To assess the different construction methods for metro excavation in loess trata，the in-situ measured date from line #2 of Xi¢an metro are considered. The four cases of geotechnical centrifugal model tests were carried on the instruments of Chang¢an University，China. The similarity ratio of test models and prototype soil body is 1∶60. A rectangular rigid container with internal dimensions of 700 mm×500 mm×360 mm was used in the centrifugal tests. Full-section construction method，mid-guiding hole and forward direction hole method，two side-wall pilot method and center diagram method were used in urban metro construction. The four kinds of construction methods on ground subsidence caused by metro excavation in loess strata were compared through centrifugal model tests. The research results show that the full-section construction method is the most effective method for metro tunneling in loess strata ；and the results also show that the primary consolidation is accounted of the majority of subsidence. This study provides a reliable foundation for urban metro design and construction in loess area.
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Received: 29 November 2006
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