Study On Stratum Deformation Law And Its Control Technology Of Shield Tunnel Adjacent Crossing Operation Subway Tunnel

Due to the advancement of urbanization construction,the subway construction has entered a new climax.The limitation of the underground space makes the construction of the adjacent tunnel more and more frequent.Therefore,it is necessary to carry out the research on strata deformation law and its control technology during the tunnel construction.Based on the project of Changsha City Rail Transit Line 3 cross under the operation of Metro Line 1,the strata deformation law caused by shield tunneling is studied by numerical simulation and field test in the thesis.The construction control technology of cross shield tunnel in red layer formation is also studied by numerical simulation in the thesis.The conclusions are as follows.(1)In terms of the deformation law of red layer formation,the results show that the change rate of the vertical displacement in the new tunnel above the vault 1.5D to the surface and in the new tunnel above the vault 1D tends to be linear,and the latter change rate of displacement with the depth than the former increased by 50%,the change rate of displacement with the depth is happened in the range of 1?1.5D to the new tunnel vault.When the first tunnel construction is completed,the displacement of the existing tunnel arch accounted for 56%of the displacement of the new tunnel,the displacement of the existing tunnel vaults accounted for 43%of the displacement of the new tunnel,the surface displacement accounts for 28%of the displacement of the new tunnel.At the same time,the right line excavation has a different degree of influence on the ground displacement above the vault of the left tunnel,and its influence degree is gradually reduced with the increase of the depth.(2)In terms of the influence of shield tunneling parameter changes on the formation disturbance,the results show that the increase of the soil cabin pressure and the grouting pressure limit the vertical displacement of the strata.In terms of the vertical displacement of the surface,the displacement growth ratio tends to be flat with the increase of the soil cabin pressure,the limit effect of vertical displacement on the surface is obvious when the soil cabin pressure is within 0.24MPa;The influence of grouting pressure on surface subsidence is significant,and the change of displacement is linearly with the change of grouting pressure.Controlling grouting pressure plays an important role in controlling surface deformation.From the vertical displacement of the surface,with the increase in the pressure of the cabin pressure,the surface uplift in front of the place of the working face 4 times the hole diameter,indicating that when the soil cabin pressure is too large,will lead to the front of the soil uplift deformation,but the pressure has little effect on the deformation of the front of the tunnel face.(3)From the impact of shield tunneling parameters on the operation of the subway tunnel structure,the increase of the soil cabin pressure and grouting pressure will help to reduce the uneven settlement of the track plate,and the variation of the soil cabin pressure within 0.24MPa is obvious for the uneven settlement of the existing tunnel.In addition,the bending moment of the vault increases with the increase of the soil cabin pressure and the grouting pressure,and the axial force of the left side also increases with the increase of the pressure and grouting pressure,but the influence are not obvious.(4)From the point of view of shield construction control,when the soil cabin pressure is 0.08MPa?0.24MPa,the grouting pressure is 0.2MPa?0.5MPa,the deformation of stratum and the deformation of the existing tunnel structure can be effective control.