Abstract: The evaluation method of lining sharing surrounding rock pressure in composite lining structure is one of the important research objectives in tunnel engineering. In this paper, an evaluating method of lining sharing surrounding rock pressure based on back analysis of monitoring displacements is proposed. Using the monitoring displacements and the lining casting time, the residual deformations of initial support are first determined; and then by useing finite element back analysis, the stresses of surrounding rock and initial support can be obtained; therefore the both of pressures behind the initial support and the lining are calculated. In order to show the applicability of the proposed procedure, the comparison of the in-situ observed and calculated is carried out for a newly built railway tunnel in which the lining is casted after 95 days in the initial support is closed. The pressure behind the lining is calculated to be about 0.04-0.06 MPa; and the ratio of lining sharing surrounding rock pressure is about 13 %-16 %. The results show that the proposed method can be useful for the design of composite lining structures.

Key words: composite lining structure, monitoring displacement, displacement back analysis, surrounding rock pressure, lining sharing surrounding rock pressure