Abstract：To study the surrounding rock pressure of loess deep large-diameter shield tunnel, the structural parameter of loess was introduced to modify the Fenner formula. Based on the interaction between the surrounding rock and the lining, the formula of plastic zone radius of surrounding rock was solved, and the calculation formula of surrounding rock pressure of the loess deep large-diameter shield tunnel was provided. Taking a deep large-diameter shield tunnel in loess as an example, the influence of structural parameter of stress ratio on surrounding rock pressure was analyzed, and the numerical calculation results of three-dimensional finite element was compared with theoretical analysis results. The results show that the radius of the surrounding rock plastic zone and rock pressure acting on the segment gradually increase with the decreases of structural parameters; the maximum value of surrounding rock pressure after shield tunneling is found in agreement with the theoretical calculation value of surrounding pressure when the structural parameter of loess is 1-Shield construction will cause loess structurally weakened. Finally, suggestions for loess shield construction and segment design were given.
