Research On The Settlement Of High-speed Railway Subgrade Induced By Railway Tunnel Construction Underpassing And Train Vibration

In recent years,high-speed railway projects of China are operated at a large scale,to enhance the function of the operation of the transportation system in our country and have a great effect on the economic development of our country.During the railway tunnel construction underpassing,free face is generated in the soil,the placement of wall rock perpendicular to the tunnel is caused,the overlying strata disturbed generate deformation step by step.And then the high-speed railway roadbed and tracks generat settlement and deformation,as a result,the normal running of high-speed railway will be influenced.with increasing of train velocity,the tunnel structure is given a bigger impact.Meanwhile,the standard of its stable performance are hieher.This paper is based on the program of Ning-Wu railway tunnel which is beneath the Beijing-Shanghai high-speed railway.This paper mainly adopts numercail simulation method to study the settlement and deformation of the high-speed railway roadbed and the stratum under the static load and dynamic load during the railway tunnel construction underpassing.The main conclusions are showed below:1.Along with the advancement of the construction step,the subgrade settlement,the ground subsidence and the vault settlement increase gradually,and tends to be stable finally.After comparing the subgrade settlement of the two-stage methods,the three-stage methods and CD methods,the paper considers CD method is better.2.For the surface transverse measuring points,the settlement decreased from junction area to both sides in a symmetrical distribution,to chek for accuracy about Peck formula.3.When the buried depth of the tunnel increases,the subgrade settlement,the ground subsidence and the vault settlement increase;This is because the tunnel cross section is relatively large,the depth increase fails to reach its critical depth within a limited scope.4.In the case of the single train,the vertical displacement response of the subgrade,the ground and the vault are increasing gradually with the deepening of the tunnel excavation,and reach their maximum after the tunnel breakthrough.As is shown,the tunnel breakthrough is the most disadvantageous position during the train passing through.5.In the case of two opposite driving trains,the displacements caused by two trains passing through reach their maximum after the tunnel breakthrough,and the subgrade settlement is the biggest,the ground subsidence is bigger than the vault settlement.The law also reflects the gradual process of decay of displacement response caused by train vibration.The maximum settlement caused by two trains passing through is bigger than the maximum settlement caused by one single train.6.There will occur unrecoverable residual deformation in the ground while the train passing through after the tunnel is completed,and the values of residual deformation are almost the same.This shows that the values of residual deformation is independent of depth.But the accumulated residual deformation of the long-term high-speed train vibration loads need to be taken seriously and taken certain treatment schemes...