Research On Soil Improvement And Cutter Life Prediction For Shield Beneath The Buildings In Complex Strata

With the rapid development of the city,the construction of the subway in our country enters the peak period,the shield method is widely used because of its high efficiency,high security and little impact on the surrounding environment.It often encounter the situation that shield beneath the buildings.To reduce the ground subsidence,to ensure the safety of the building has become the top priority.Muck improvement and the selection of tool changing station that guaranteed shield to beneaththe buildings successfully are key technical.According to the geological condition of Shenzhen Metro Line 7 from Fuming station to Huanggangkouan station,determining the modifier and the sample and waste improved experimental design.Through the slump,penetration and mixing motor test,drawing the best foam added ratio with different geological conditions.The test results are applied to the field for verification.By comparing before and after soil improvement,sediment temperature,shield earth pressure changesafter shutdown and the state of muck,gettingtest results is accurate.The test results are applied to soil improvement when shield is driving.At the same time recording the abrasion loss of front hob.According to the working principle and wear mechanism of hob,the hob life prediction model is established.Compared with the measured value and the predicted value,the difference is not big,and the model is accurate.Based on the model,the maximum distance of the hob with different mounting radius is obtained and find out the shortest distance in all hobs.According to the length of the lower section of the building,the shortest driving distance of the hob and the influence range of the shield stop,the best tool changinglocation is determined.The building settlement,tunnel vault settlement and horizontal convergence are monitored when shield beneath the buildings.The monitoring results are small andshield tunneling smoothly and buildings are safe.It can be concluded that the all preparations are adequate before shield beneath the buildings,Soil improvement bubble ratio and hob life prediction model are accurate.The hob life prediction model and soil improvement scheme proposed in this paper reduce the risk of shield beneath buildings.The research results can be well combined with the actual shield construction,and play a guiding role for the similar projectsin the future.