Research on the boundary value of high hydraulic pressure upon lining in deep-lying single-track railway tunnel

How much of hydraulic pressure value upon lining may be intituled high hydraulic pressure? Now, there isn't clear boundary value in the field of tunnel engineering. The boundary value of high hydraulic pressure was researched by calculating and analyzing the safety factor of lining whether achieving the railway tunnel design code requirement or not, using plane FEM based on standard design drawings of single-track railway tunnel, needn't change the shape of standard design cross-section as principle. The results show that in single-track railway tunnel, the first boundary value of high hydraulic pressure upon upright wall lining is 0.050.10 MPa and the second boundary value is 0.18 MPa; The first boundary value of high hydraulic pressure upon curved wall lining is 0.20 MPa and the second boundary value is 0.40 MPa. Hydraulic pressure is the main load upon lining when its value is higher. The boundary value of high hydraulic pressure is rarely related to the surrounding rock classification but is closely related to the shape of lining section. Curved wall lining's capacity hydraulic pressure bearing is far higher than upright one. The capacity hydraulic pressure bearing of standard design section in single-track railway tunnel is limited. Other optimized sections should be used when static head is higher than 40m.