Shield Tunneling Rate Prediction Model for Complex Rock Stratum

Abstract

In order to improve shield tunneling performance and provide guides for shield construction, prediction models of shield tunneling rate in alternation of mud rock and sand rock stratum of Chongqing Yangtze River tunnel were discussed. Based on the field shield excavation tests, shield tunneling data were acquired by data acquisition and storage system of shield machine. Meanwhile rock point load index (PLI) tests were carried out to produce rock strength parameters. Subsequently, the relationships of shield tunneling rate with PLI and thrust force of cutter wheel were studied. Upon the above data and analysis, tunneling rate prediction models of mud rock and sand rock strata were built by means of multiple regression analysis method. The research and application show that (1) in the two strata, the higher the rock strength, the lower the tunneling rate, and the higher the thrust force of cutter wheel, the faster the tunneling rate; (2) the relationships of tunneling rate with thrust force and point load index are all subjected to exponential function. The models can be used conveniently with simple form, few parameters, and high precision. Simultaneously the models can also be used to perform back analysis of rock PLI only with simple transposition.