Research On Simulation And Prediction Of Rock Pile Slope Deformation Trend Of Daqian Shiling Tunnel During Operation Period

Talus slope are one of the dverse engineering geologic phenomena and are obviously affected by the engineering construction.It is very important to study the deformation of talus slope under reservoir water fluctuations during the tunnel operation.This study is based on the prototype talus slope of the Daqian Shiling Tunnel of the Tianhuan Railway in Liaoning Province,China.Searched many relevant literatures and surveyed the terrain and geomorphology,geological structure,hydrogeological conditions in field.Learned the schem for prevention slopes in the entrance of the Daqian Shiling Tunnel during the excavation.At the same time,the surface displacement was monitored and analyzed.The three-dimensional geological mechanics numerical model was established and calculated by CAD,ANSYS and FLAC3D.Based on the calculate,the tunnel excavation results show that the stress and deformation characteristics of rock slope after tunnel excavation coincide with the actual monitoring results,which can serve as a basis for deformation prediction in operation period.Further,the characteristics of stress and deformation of the talus slope under the reservoir water fluctuation and train load are predicted.The results show:(1)Under the natural condition,the stress distribution of talus slope is even and the displacement is small.After the tunnel excavation,the surrounding rock stress is redistributed.The surrounding rock domes and sidewalls showed significant stress concentrations.There is a potential sliding surface in the rock face and the entrance of the tunnel.It consistent with the actual conditions.After the excavation of the tunnel,the numerical simulated displacement values of the five monitoring points on the surface are in good agreement with the displacement of the actual monitoring point,which can be used as the basis for predicting the trend of slope deformation during tunnel operation period.(2)After the reservoir water rises,the stress in the z direction decreases due to the floating force of the reservoir water at the leading edge of the slope,and the stress in the y direction increases slightly.The shear strain increment in the leading edge of the slope is obviously increased.The displacement gradually decreases from the foot of the slope to the top of the slope.The talus slope transform pushed deformation to traction deformation.When the reservoir water rises,the top and front edge of the slope are dominated by tension force.The center of slope is dominated by shear force.The shallow sliding area is easy to appear on the bank.(3)After the reservoir water drops,the stress distribution on the slope was similar to the reservoir water rises.The reservoir water floating force in front of the talus slope has played a role.The compressive stress on the slope was slightly increases,which can improve the stability.The rise of reservoir water has a greater impact on the deformation of the talus slope than the reservoir water drop.After the reservoir water drops,the shear strain increment and distribution area is small.The foot of the slope is deformed.The displacement value is small.There is no change in the plastic zone,indicating that the decline of the reservoir water has little effect on the stability of the slope.(4)Under the fluctuation of reservoir water,the shear strain increment and deformation in the reinforced area in front of the tunnel entrance are obviously smaller than in the unreinforced area.The post-pile deformation is significantly larger than the pre-pile deformation,indicating that the anti-sliding pile can effectively control the increase of shear strain increment induced by the reservoir water.(5)The talus slope stress change under the train load is small during the operation.The shear strain increment at the rising stage of the reservoir water and train load is larger than the stage of water reservoir drop.After the water level rises,the tunnel front entrance is the region where the shear strain increase is concentrated.After the water level falls,between the tatlus slope and the bedrock interface and the tunnel dome where the shear strain increment is concentrated.In general,the shear strain increment and the displacement are small,indicating that the train vibration has little effect on the slope stability.In general,the stability of the Daqianshiling tunnel talus slopes under the condition of reservoir water fluctuation has a little influence but it is still in a safe state during the operation.