Research On Adaptability Evaluation For EPB Shield Tunneling In Composite Strata

Based on safety, reliability and advanced technology, EPB shield machines are widely used in the construction of city metro, underwater tunnel and underground pipeline projects, and great success has been achieved already. China is a large country with all kinds of complex geological conditions, the advancing performance of EPB shield machines working in different strata changes greatly. Therefore, study on the adaptability of EPB shield in complex strata caused more and more attention, the South China area is widely distributed compound formation, this paper carry out the EPB shield for adaptability research, which has important theoretical significance and practical value.The main contents of this paper and the results are as follows:(1) Research the domestic and foreign EPB shield machine adaptability research status, raise the existing problems of EPB shield machine adaptability. Review the meaning and evaluation method of EPB shield machine adaptability, propose to ues the fuzzy comprehensive evaluation method for EPB shield adaptability evaluation through the comparison of the advantages and disadvantages of the various evaluation methods, with EPB shield adaptability evaluation.(2) Determine the influence factors of EPB shield, using the AHP to determine the weights of the influence factors, and reduction to obtain the evaluation index, then establish the adaptability evaluation index system of EPB, which is mainly divided into four parts:the design of shield machine, the construction of shield machine, the formation of stratum and the surrounding environment. Include target layer, criteria layer and the index layer, target layer is EPB shield fitness D, criteria layer include shield design P1, shield tunneling P2, the formation conditions P3, index layer composed of10specific indicators, shield design indexes include total design thrust u1, knife wheel torque u2, the opening rate design u3, screw conveyor the slag quantity design u4and cutter spacing design u5; shield construction indicators include soil pressure u6, grouting pressure u7, gap of the shield tail u8; formation condition index include mix ground u9, spherical weathered stone u10.(3) In order to solve the different indexes in evaluating the commensurability of the problem, based on fuzzy mathematics method and consider the attribute of each index constructed evaluation index membership function. Through the feedback and the engineering consulting experts, combined with analytic hierarchy process and fuzzy comprehensive evaluation method to build the earth pressure balance shield machine adaptability evaluation model, put forward the composite strata EPB shield machine adaptability evaluation method.(4) Take the Che Hong section and Nan Qian section from subway line11in Shenzhen composite stratum as an example for adaptability evaluation with the EPB shield adaptability evaluation model. According to the principle of maximum degree of membership, the left and right line of Che Hong section and Nan Qian section EPB shield fitness is "adaptation", according to project headquarters report, two zones of line11have been successfully through, this EPB shield meet the actual needs of the project to verify the model is effective.