Abstract Water seepage of a karst tunnel section in soil surrounding rock is prone to surface subsidence. Considering the settlement caused by descending of water level due to water leakage, a method of surface settlement estimation under steady seepage of phreatic water was proposed. Based on the seepage and consolidation theory, the changes of dead-weight and seepage effective stress of soil unit in surrounding rock was analyzed in condition of water seepage,and the settlement zone of surrounding rock was divided by taking the funnel curve of precipitation as the boundary line. A two-dimension plane was established based on the excavation cross section and the estimation formula for surface settlement due to seepage effect was deduced by means of double integral. On the basis of Yaozhai tunnel of Liuzhai-Hechi Expressway in Guangxi Zhuang Autonomous Region, the surface settlement of soil surrounding section was predicted by field measurement and formula estimation respectively. Facts and figures show that the measured values are mainly consistent with the estimation ones, while the measured values are larger than the estimation ones within the scope 3 m away from the excavation face along the horizontal radial direction.
Abstract：
Water seepage of a karst tunnel section in soil surrounding rock is prone to surface subsidence. Considering the settlement caused by descending of water level due to water leakage, a method of surface settlement estimation under steady seepage of phreatic water was proposed. Based on the seepage and consolidation theory, the changes of dead-weight and seepage effective stress of soil unit in surrounding rock was analyzed in condition of water seepage,and the settlement zone of surrounding rock was divided by taking the funnel curve of precipitation as the boundary line. A two-dimension plane was established based on the excavation cross section and the estimation formula for surface settlement due to seepage effect was deduced by means of double integral. On the basis of Yaozhai tunnel of Liuzhai-Hechi Expressway in Guangxi Zhuang Autonomous Region, the surface settlement of soil surrounding section was predicted by field measurement and formula estimation respectively. Facts and figures show that the measured values are mainly consistent with the estimation ones, while the measured values are larger than the estimation ones within the scope 3 m away from the excavation face along the horizontal radial direction.
2018, Vol. 55 