Load tests on segment joints of single lining structure of shield tunnel in Qingcaosha Water Conveyance Project

The key parameters for models of lining structure of shield tunnels, such as bending stiffness of radial joint s, shear stiffness of radial ( circumferential ) joints and moment transfer coefficient , have always been the research focus in this field. The above key parameters are studied by means of the prototype load tests on segment joints in Qingcaosha Water Conveyance Project. The test results indicate that under sagging moments the bending stiffness coincides with the bilinear model, and under hogging moments it is similar to the linear model. The bending stiffness of radial joint and its variation law are different from those of various joint structures. According to the results from shear tests the dislocation change process of radial (circumferential) joint can be divided into three stages. The dislocation occurs mainly at the second stage. The results of moment transfer tests indicate that the moment transfer coefficient decreases with the increase of load. The greater the bending stiffness of radial joint is, the less the moment transfer coefficient is, and vice versa. Finally, based on the test results, the value range of the key parameters for the models of lining structure of shield tunnels is put forward. Several beneficial conclusions for the design of lining structure of shield tunnels are drawn.