| The continuous expansion of cities and the ever-increasing urban population are a severe challenge to ground transportation.The development and vigorous construction of underground rail transit has eased the pressure on ground transportation,and many cities at domestic and foreign have carried out subway construction.This article is based on the tunnels between Lanhua Road Station and Nanhu Station and the tunnels of the access section of the second phase project of Chongqing Rail Transit Line 10,research on the evaluation of curtain grouting effect and construction mechanics effect of the tunnel group in the deep backfill area.Firstly,This article analyze the characteristics of the backfilled soil of the supporting project,and obtain the physical and mechanical parameters of the soil-rock mixture before and after grouting in the backfilled soil area through indoor tests;Secondly,use methods such as detection,inspection and indoor test to comprehensively evaluate the effect of tunnel curtain grouting in the backfilled soil area.Established Midas-GTS NX three-dimensional finite element numerical model,which studied the mechanical effects of the excavation of the reserved core soil method of the tunnel group from the three aspects of surrounding rock deformation,stress and plastic zone distribution characteristics,and optimize the excavation plan and construction sequence;Finally,the influence of the excavation of the tunnel group in the backfill area on the adjacent existing reinforced earth retaining wall and drainage box culvert is analyzed.The main research content and work are as follows:(1)A large-scale indoor direct pressure test was carried out on the soil-rock mixture in the backfill area,and the design bulk density,equivalent gradation curve and moisture content of the soil-rock mixture with different confining pressures were obtained,and the large-scale triaxial test of the soil-rock mixture under different confining pressures were calculated.Through large-scale triaxial compression tests,physical and mechanical parameters such as cohesion c and internal friction angle of the soil-rock mixture were obtained,which provided a parameter basis for the numerical simulation.(2)Comparison of the grouting amount and grouting pressure during the curtain grouting process of the tunnel group with theoretical calculations,comparison of multi-wave and multi-component engineering seismic exploration graphics before and after grouting,high-definition video detection of boreholes after grouting,and indoor wave speed test of grouting body samples comprehensive evaluation of curtain grouting effect with uniaxial and triaxial compression tests.(3)Using finite element software to carry out numerical simulation analysis of the tunnel group construction process,and analyze the mechanical effects of tunnel group construction in the backfill area from the deformation,stress and plastic zone of the surrounding rock and supporting structure;through the reserved core soil method,The comparative analysis of the step method and the optimized step method have put forward an optimized construction plan.(4)Through numerical simulation,the influence of tunnel group excavation in the deep backfill area on the existing reinforced earth retaining wall and drainage box culvert is analyzed,and risk pre-control measures are put forward. |
PDF Full Text Request