The Shallow Tunnel Mining Method Construction's Impact Study On The Stratum And Buildings

This paper based on a underground tunnel of the Dongguan to Huizhou's intercitypassenger rail. By field measurement and numerical analysis, systematic study of the miningmethod tunnel construction to the stratum deformation of the influence law, and forecastanalysis for the subsequent tunnel underneath the building. The author puts forward somecontrol measures, the main results are as follows:(1)Surface subsidence caused by tunnel excavation can be divided into four stages: tinydeformation stage, sharp deformation stage, slow deformation stage, stable deformation stage.(2)Lateral surface subsidence slots caused by double tunnel excavation with left and rightline to the boundary line is degressive, or so line between midline settlement superposition andthe distance is near, lead to the final settlement is bigger, tend to be a straight line. In the centralline2D place the final settlement over200mm, its influence range far outweigh the2D range.(3)Generally speaking, the stratum deformation is gradually developing from hole weeksto surface extension. Considering bearing strata arch effect, the vault sink value should be morethan the surface subsidence value. But from this project to see, when the local soil layer isspecial and the groundwater is rich, the surface subsidence value more than vault sink value isthe fact that doesn't dispute.(4)In the numerical simulation, the measured value and the calculated value isaccordanced of horizontal convergence and vault sink, but the surface subsidence appears a bigdifference. The reason is this project of some special factors leading to the tunnel hydrophobicsurface subsidence far greater than the surface subsidence caused by loss formation. And thencan speculate, the soil structure might have been destroyed caused by tunnel hydrophobicprocess, and the stress state have a lot of change, also the soil deformation become complex anderratic.(5)Due to the construction site don't have a very good control on CD method betweeneach step interval, the numerical calculation and the field measured data show that strata losslead to large deformation. Contrast the excavation step before and after adjusting ordernumerical analysis, the results show that the tunnel excavation of the deformation caused bystrata loss obviously controlled. The subsequent construction should be correct in theconstruction of the excavation process, thus reduce risk construction, and put the surroundingenvironment influence to the minimum.(6)Numerical calculation shows that the tunnel construction influenced mainly forbuildings in2D range. There will be a big risk of buildings if don't take any measures cases, so put forward the specific control measures. Minimize the influence of groundwater through thewhole section grouting. Strengthen pre-reinforcement measures that change advance singlesmall catheter to double row or bassoon and tent grouting. Methods for conversion that changeCD to CRD, realize closed cyclization step, reduce the risk of buildings. Through dynamicgrouting and monitoring measurement, feedback, adjust grouting parameter, dynamic groutingcontrol building sinking.