Study On The Key Technology Of Shield Tunneling In Small Radius Curve Tunnel In Composite Stratum

Most of the strata in Zhuhai area are composed of upper soft and lower hard strata,with complex geological conditions.Most of the shield tunnels are built in the urban area.There are many buildings and other facilities above the line,and there are many technical problems in the construction,which makes the construction of EPB shield difficult.Based on the 1 ～ Bay section of Zhuji inter city shield tunnel,it is urgent and important to study the design and construction key technology of small radius curve tunnel in composite stratum in China.In this paper,based on the collection of shield tunneling parameters and geological parameters of Zhuji inter city shield tunnel in 1 ～ Bay and 4 ～ cross sections,the statistical rules,model prediction and mechanical properties of small radius tunnel segments are studied.The main research contents and achievements are as follows:(1)This paper investigates the research status of shield tunneling parameters and model prediction at home and abroad,analyzes the advantages and disadvantages of the current model prediction,and determines the improvement methods and methods for the shortcomings.(2)Based on the principle of selecting driving parameters,the paper selects the parameters of shield driving in the typical upper soft lower hard composite stratum,and adopts the mathematical statistics method to compare and analyze the changing laws of earth chamber pressure,total thrust of main drive,torque of cutterhead,rotating speed of cutterhead,propulsion speed of main drive and penetration of cutterhead under different stratum conditions,and gives the changing rules of shield driving in the composite stratum conditions Recommended value of parameter construction.Then the correlation between the driving parameters is analyzed.(3)The PSO-BP neural network model based on BP neural network is established through the research of PSO and BP neural network principle and algorithm.The main driving parameters of shield machine are predicted by the network model,and the training effect of the model is compared and analyzed.Then the model is used to predict and analyze the actual driving parameters.The results show that the model is accurate degree and prediction range can meet the requirements of site construction,and have a certain guiding role for the actual project construction in Zhuhai area.(4)By using the stratum structure method and midas-gts software,three shield tunnel models with different curve radii are established.Each model is calculated under the action of four kinds of jack thrust respectively,so as to study the force and deformation law of shield tunnel pipe under different curve radii and different Jack thrust.The research contents and results of this paper can provide some guidance for the selection of parameters of EPB shield tunneling in Zhuhai area,and have strong practical significance.