Study On The Control Measure For Tunnel Crossing The Third Series Of Sand Mudstone

In this paper,based on the actual project of tunnel from Mudanjiang to Harbin,through on-site monitoring and numerical simulation,the control measures of the tunnel through third serious of sand and mudstone are analyzed.The main work and achievements of this paper are as follows:(1)The mechanism of pre reinforcement was analyzed.Discussing the grouting process from the following three aspects: the osmotic grouting,analyzing the slurry in the surrounding rock by which form spread,and eventually reaching the effect of grouting.(2)Based on the actual DK293+587(without grouting)and DK293+626(curtain grouting)of monitoring and measurement,the data after finishing analysis concluded that: in the DK293+587 section,as a result of the controlling measures is not ideal,this part of the surrounding rock deformation is large,especially for the settlement of vault has already reached to 64.3 cm,in the process of deformation,the initial deformation is bigger,faster,and finally achieved stable was reaching long time.The ultimate stable stress of steel arch is up to 453 MPa,which has reached the yield state.In the DK293+626 section of curtain grouting,the displacement situation was improved,reaching the stable time was shortened,the vault settlement value is only-16 cm,reduced 3/4,the finally maximum stress of the steel arch shelf is-209 MPa,reduced by half.(3)The tunnel excavation is simulated under three conditions: no pre-reinforcement measures,grouting of the surrounding rock and pipe shed.Simulation results of no pre-reinforcement measures: the settlement value of the vault is-65.59 cm,and the horizontal displacement value of the left and right sides of the middle step is 19.15 cm and 11.22 cm,which is close to the actual monitoring results.By grouting of the surrounding rock,the result is as follow: the settlement value of the vault is-17.42 cm,and the horizontal displacement value of the left and right sides of the middle step is 9.62 cm and 5.72 cm,which is also close to the actual monitoring results.The stress of steel of the vault without pre-reinforcement was-311.15 MPa,however,in the grouting of the surrounding rock,the stress of the vault was-138 MPa,both of which were consistent with the actual measurement results.(4)Through the pipe shed simulation of the 80°,100°,120° three advanced reinforcement range,the vertical displacement of the left arch waist is analyzed,the results are-53.21 cm,-51.13 cm and-44.41 cm respectively.Reserved in the process of tunnel construction of 50 cm,so only the 120° reinforcement range can meet the requirements.But compared with grouting of the surrounding rock,the effect is not very ideal,therefore,taking the measure of grouting of the surrounding rock is necessary.(5)By using the method of theory analysis,the inspection hole and the actual situation of grouting and assessing the effect of grouting,it is concluded that the implementation of the grouting measures has obvious reinforcement effect for the relatively loose strata,meeting the requirements of the excavation,and the construction is smoothly.