Hydraulic Model Test and Mechanical Behavior of Lining Structure in the Water-filled Large Cross-section Highway Tunnel

In order to study the stress characteristics, structural safety and failure modes of the tunnel lining under the effects of surrounding rock pressure and external water pressure, a self-made homogeneous hydraulic pressure simulation device and a tunnel stratum composite test bench were used to simulate the loaded of different external water pressures under deep burial. Studies show that when using vacuum to simulate the external water pressure method, the greater the external water pressure value, the smaller the test error. When the external water pressure reaches 150 kPa, the error can be controlled within 5%; in the case of fixed depth As the external water pressure increases, the axial force and bending moment of the lining increase continuously, and the increase rate is basically linear; as the load increases, the toe of the lining structure first breaks, and the continuously cracking of the toe of the lining, resulting in redistributing of the structural stress, eventually cracks in the inverted arch; cracks in the walls cause the permanent bending moment at the foot of the wall to continue to decrease, and the negative bending moment of the inverted arch continue to increase, and the safety factor continue to decrease. When the bending moment of the foot of the wall fall to 85% of that before cracking, the safety factor of the invert is reduced to 1.41 and the invert arch crack and destroy. This article involves the model test program can provide a reference for similar numerical model test, the research results can provide a basis for the design and safety assessment of water-rich large section highway tunnel. © 2019, Editorial Department of China Journal of Highway and Transport. All right reserved.