RESEARCH ON IN-SITU TEST OF MECHANICAL BEHAVIORS OF LINING IN NEW-STYLE RAILWAY TUNNEL PORTAL
新型铁路隧道门洞口段结构受力特征现场试验研究

Railway tunnel portal is always designed according to the standard drawing with experience. Research on new-style tunnel portal is necessary. Besides a new-style tunnel portal should have aesthetic effect and be beneficial to protect environment,it should be ensured security of the structure. Surrounding rock pressure and mechanical behaviors of lining in the new-style tunnel portal had been tested in-situ. The distributed characters of surrounding rock pressure and mechanical behaviors of lining are discussed,by comparing the test results with model experiment and finite element analysis results. The results show that the surrounding rock pressure and internal force of lining increase from the tunnel entrance to inside in the bamboo-truncating tunnel portal. The value increases with the depth of cover. The pressure of surrounding rock is maximal at the invert arch. And the lining is in complicated three-dimensional mechanical state. There are not only circumferential axial force and bending moment but also longitudinal axial force and bending moment. The mechanical behaviors of lining are similar to those of shell structure. So it is reasonable to design lining for the tunnel portal as a shell structure.