EXPERIMENTAL FAILURE ANALYSIS ON CONCRETE SHEAR KEYS IN IMMERSION JOINT SUBJECTED TO COMPRESSION-SHEAR LOADING

When the immersed tunnel is subjected to earthquakes, differential settlement or/and other loadings, transversal deformation occurs and is transferred by the shear keys in the immersion joint, which is deemed to be the weakest part in immersed tunnel. So far, in consideration of researches on immersion joint, only few of them focus on shear keys and most of them are lack of support from the experiments on the behavior of the whole immersion joint. Based on the characteristics of the immersion joint, a testing method and a loading scheme are proposed to obtain the shear capacity and failure mode of the joint. With the geometric scale of 1:10, the model was designed and the compression-shear test was carried out to investigate the mechanical behavior of the joint subjected to low frequency cyclic loading. The load-displacement curves of the joint and the shear stiffness are recorded. The results indicate that the shear capacities of the joint and one single shear key are 310 kN/355 kN (+/-) and 88 kN respectively, which are both higher than the designed values. The local warping failure and tension failure in the root of tenon are regarded as the failure mode of the concrete shear keys.