Study On The Ground Settlement In Shield Construction Of Metro Tunnel

With the acceleration of urbanization process and the continuous growth and development of public transport,land resources are becoming more and more tense.In order to alleviate this resource tension and make more effective use of limited resources,underground transport came into being.However,in the process of subway construction,there will inevitably be a series of impacts caused by construction.In this paper,taking the shield section from Heping Road station to the East 2nd ring station of Hefei rail transit line 4 as the main research background,through the combination of field measurement and 3D modeling software MIDAS/GTS,the research on controlling and predicting surface settlement is theoretically analyzed,and the reasonable and effective control measures for reducing surface settlement are put forward.1)According to the analysis of the field measured data,the general rule of the cumulative horizontal surface settlement is that according to the monitored settlement value,it can be divided into two areas affected by the surface settlement within the range of 6m above and below the central axis of the shield,which are the main and secondary areas.The impact of the main impact areas on the cumulative surface settlement accounts for most of the proportion During this period,the accumulated settlement on the surface of the land increases greatly,and vice versa;the general rule of the accumulated settlement on the longitudinal surface is that according to the distance from the shield excavation surface,the accumulated settlement on the longitudinal surface can be regarded as three different periods,namely,the slow growth period,the rapid growth period and the gradual stable period.At the same time,we can also regard these three periods as three stages of the shield machine,namely,before the arrival of the shield machine,when the shield machine arrives and after the shield machine passes.2)The 3D finite element analysis shows that the construction simulation process is similar to the actual construction.According to the construction simulation process,the soil in the lower part of the lining is generally uplifted,and the soil in the upper part of the lining is generally sinking.The selected actual construction case of the shield section between Heping Road and East 2nd Ring Road Station of Hefei rail transit line 4 should be constructed under the condition of H=24m and deeper buried depth and the propulsion pressure of 7500kn-10000kn,which can effectively reduce the generation of surface settlement.3)According to the field measurement and three-dimensional finite element analysis,it is necessary to adopt grouting technology to control the ground settlement in the subway tunnel engineering in this section,so as to obtain good results.Based on the above analysis,this paper deeply reveals the law of surface settlement under the conditions of different burial depth and different propulsion force,forms a set of feasible surface settlement control measures,and provides some reference for similar metro tunnel shield construction.Figure[41]table[3]reference[45]...