Study On Slope Displacement Of Wanzhou Bank Of The Daning River Bridge Under The Fluctuation Of Reservoir Water Level

Zhengzhou-Wanzhou high-speed railway is being built in Guihua Village,Wushan County,Chongqing in the form of a double track bridge with span 372 m across Daning River.Since the limestone bank of the bridge abutments is located in the Daning River reservoir which belongs to the three gorges reservoir,the reservoir water level fluctuates between the flood water level of 145 m and the electricity generation water level of 175 m per year.The periodic fluctuation of the water level may affect the long-term stability of the bridge bank slope,and even the safety of the bridge.Therefore,it is necessary to study the stability characteristics of the bank slope of the Daning River Bridge under the long-term reservoir water level fluctuation,especially the stability characteristics of the Wanzhou bank slope of the Daning River Bridge in the bedding structure.Based on the field investigation and observation of rock displacement characteristics in fluctuation area of bank slope,a physical model test on the scale of 1:60 was built indoor to study the influence of the slope surface displacement under the long-term water level fluctuation by calculating slope infiltration surface seepage using SEEP/W,deducing and establishing the formula of dynamic and static water pressure of rock under the action of groundwater,embedding formula in the UDEC and some other technologies.Using this method,this paper set up 27 numerical analysis models with variable parameters of displacement of slope rock mass under water level fluctuation to simulate and caculate the relationship between slope displacement caused by water level fluctuation and slope angle,bedding angle,gap width,layer thickness and joint connectivity ratio with the empirical formula finally proposed.On the basis of the study,rock displacement of wanzhou bank slope of Daning River Bridge under long-term water level fluctuation was forecasted through comprehensive analysis of results obtained from various methods,such as field test,model test,the empirical formula,numerical analysis methods and the like.The results show that the displacement of the surface rock mass in the fluctuating zone of the Wanzhou bank of Daning River Bridge in 50 years can up to 0.37 m,and it is suggested that the reinforcement measures be taken for the rock mass within 5m range of the fluctuation zone.The results of this paper can not only provide the basis for the reinforcement engineering of the wanzhou bank,but also have some reference value for similar projects.