Seasonal Temperature Deformation Of Open-Excavated Underwater Tunnel And Preliminary Study On Its Environment Effects

The internal temperature difference of open-excavated underwater tunnel is mainly derived from the inside environment seasonal temperature of the tunnel,and the structure of tunnel generated deformation and displacement,especially at the position of deformation joint,under the seasonal temperature difference.The Seasonal temperature deformation would increase the width of deformation joint or occur the compression.It could cause tunnel damage and leakage.Based on the example of Du-Shu-Hu tunnel,this paper combined the field test,the finite element numerical simulation and the indoor simulation experiment,and studied the displacement variation of deformation joint under different temperature condition.In addition,this paper also qualitatively evaluated the disturbance in the upper soil layer and influence factors.The main results and conclusions are as follows:(1)The internal temperature of tunnel and the displacement of deformation joint were changed by the regular fluctuation of the sine curve.The displacement of tunnel deformation joint was strongly correlated with the internal temperature difference,and the fitting function was been obtained.(2)When the average temperature of September was used as the initial temperature,the variation of the temperature deformation of deformation joint was the same during the heating period and cooling period:the position of deformation joint was the biggest displacement of the box-culvert in two kinds of temperature difference conditions,and was decreasing to the center of the box-culvert with the shape of "concave".In the vertical direction of the profile of tunnel,the distribution of the deformation joint’s displacement was like the "shearing" curve,and the upper roof displacement reaches the maximum.In the horizontal of the profile of tunnel,the distribution of the deformation joint’s displacement was like the "double peak" curve,and the maximum was reached in the middle of the lane(3)When the initial temperature of tunnel was different,the temperature difference becomes larger and the displacement of the deformation joint increases gradually with the increase of the initial temperature(cooling period)or decrease(heating period).From the point of tunnel section,with the increase of the temperature difference,the trend of the deformation joint’s displacement was obvious,which it was the "shearing"curve in the vertical direction and the "double peak" curve in the horizontal direction.(4)In the tunnel,if the initial temperature of tunnel was higher,the construction period was in summer,the width of deformation joint would be reduced properly.It could prevent the leakage when the temperature was lower.If the initial temperature of tunnel was lower,the construction period was in winter,the width of deformation joint would be normal or wider.It could prevent the compression of deformation joint and the damage of the structure.(5)The seasonal temperature deformation of deformation joint could disturb the upper soil layer and make it cause cracks.The degree of disturbance had relationships with the moisture content and dry density of the upper soil layer.With constant dry density,higher water content lead to lower tensile strength thus caused cracks in soil samples more likely.With constant water content,lower dry density lead to lower tensile strength thus caused cracks in soil samples more likely.