Abstract The high local water pressure applied on tunnel linings is one of the main reasons for lining cracking af?
ter operation. To address the insufficient theoretical design basis for linings that are subject to local water pressure,field tests and a numerical simulation method were used to study the mechanical characteristics and safety behaviors of linings under local water pressure in terms of the standard design drawings of a single-track railway tunnel,namely a curved wall with the floor in grade Ⅱ rock and a curved wall with the invert in grade Ⅲ rock. The effects of the measures to improve lining safety were analyzed, and the design parameters for the lining under local water pressure were put forward. The results show that: 1) the distribution of safety factors at various lining parts is much more scattered in the case of local water pressure, with the lining part subjected to local water pressure being the
weak point; 2) the safety of the reinforced concrete lining can be improved by increasing the lining thickness and the amount of reinforcement rather than increasing the concrete grade; and 3) the safety of the curved wall with an invert is obviously better than that of the curved wall with a floor. By increasing the lining thickness and the amount of reinforcement, the lining structure of the curved wall with a floor and the curved wall with an invert can bear a water pressure of 0.2 MPa and 0.5 MPa, respectively. In the case of higher water pressure, it is recommended to increase the curvature of the curved wall to improve the lining safety.
Abstract：
The high local water pressure applied on tunnel linings is one of the main reasons for lining cracking af?
ter operation. To address the insufficient theoretical design basis for linings that are subject to local water pressure,field tests and a numerical simulation method were used to study the mechanical characteristics and safety behaviors of linings under local water pressure in terms of the standard design drawings of a single-track railway tunnel,namely a curved wall with the floor in grade Ⅱ rock and a curved wall with the invert in grade Ⅲ rock. The effects of the measures to improve lining safety were analyzed, and the design parameters for the lining under local water pressure were put forward. The results show that: 1) the distribution of safety factors at various lining parts is much more scattered in the case of local water pressure, with the lining part subjected to local water pressure being the
weak point; 2) the safety of the reinforced concrete lining can be improved by increasing the lining thickness and the amount of reinforcement rather than increasing the concrete grade; and 3) the safety of the curved wall with an invert is obviously better than that of the curved wall with a floor. By increasing the lining thickness and the amount of reinforcement, the lining structure of the curved wall with a floor and the curved wall with an invert can bear a water pressure of 0.2 MPa and 0.5 MPa, respectively. In the case of higher water pressure, it is recommended to increase the curvature of the curved wall to improve the lining safety.
.Research on the Design Parameters of a Single-Track Railway Tunnel Lining under Local Water Pressure[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(3): 8-16
2017, Vol. 54 