Statistical Analysis Of Subway Shield Tunneling Parameters And Stratum Adaptability

During the shield tunneling process of the subway,the tunneling parameters of the subway are affected by the formation conditions and the surrounding wall rock,which will produce different changes.Due to the differences in geotechnical and mechanical properties of different strata conditions,the driving parameters must be different.The adaptability of shield tunneling parameters and different stratum conditions can improve the efficiency of shield construction and ensure construction safety.In this paper,the sections of Minzhi Station to Wuhe Station of Shenzhen Metro Line 5and Shenmei Road to Fanrong Road of Shanghai Metro Line 18 are selected as the research objects.Using mathematical statistical methods,the tunneling parameters and geotechnical and mechanical indicators of shield construction are statistically calculated.The variation between the main tunneling parameters of the shield machine and the main geotechnical and mechanical parameters under different formation conditions is analyzed.And use MIDAS GTS to carry on the simulation analysis and the numerical calculation to the shield tunneling,further study and verify the subway shield tunneling parameters and the adaptability law of different strata.The main contents are as followed.(1)Select the four key driving parameters of cutter torque,cutter speed,excavating velocity and total thrust and five physical and mechanical indexes such as the moisture content w,bulk density γ,compression modulus Es,internal friction angle φ and cohesion c for correlation statistical analysis,and the statistical rules of subway shield tunneling parameters and strata adaptability in the weathered granite composite strata between Minzhi Station and Wuhe Station of Shenzhen Metro Line 5 were obtained.(2)Due to the changes in the physical and mechanical properties of the residual soil layer traversed by the shield machine,the tunneling parameters such as the cutte speed,cutter torque,excavating velocity,and total thrust of the shield machine have different degrees of fluctuation in different layers.In the process of traversing the granite formation and the composite formation,the curves of cutter torque,total thrust and excavating velocity fluctuated significantly.When crossing the boundary between two different strata,the cutter head speed changes significantly,and when shield tunneling is carried out in the formation made of gravel cohesive soil,the cutter speed tends to a relatively stable fluctuation state.(3)Select the four key driving parameters of cutter torque,excavating velocity,total thrust,earth bunker pressure and the driving parameters of the shield machine through the stratum to perform correlation statistical analysis with physical and mechanical indicators,and obtain Shenmei Road to Fangrong Road of Shanghai Metro Line 18 statistical rules of subway shield tunneling parameters and stratum adaptability in soft soil strata.(4)Soft clay has high natural moisture content,low strength and small internal friction angle.When shield tunneling is carried out in a soft soil layer,the cutter torque and the excavating velocity are both stable within a range.This interval is a large area covered by soft clay,and the soil layer is relatively uniform.The change is relatively flat.Compared with hard rock formations,the thrust required for shield tunneling is significantly reduced,the cutter torque is reduced,and the excavating velocity is smaller and unstable.Taking into account the formation characteristics of soft soil,low thrust,low speed and low speed propulsion are adopted.(5)As the soil pressure increases,the influence area of ??the shield advancement on the front soil increases,and the displacement of the front extrusion disturbance zone increases significantly.The impact of the shield on the lower soil body during the tunneling process is relatively small,with the smallest increase in earth pressure at the bottom of the shield and the largest increase in earth pressure above the central axis of the shield.(6)Using the Midas GTS to perform finite element numerical simulation to simulate the change of shield parameters under different formation conditions,and compare with the measured data,the results show that the shield tunneling parameters and the changes in physical and mechanical indicators are roughly consistent.