Compression-bending behavior of a scaled immersion joint

The mechanical behavior of an element joint of an immersed tunnel subjected to quasi-static axial compression and horizontal bending is investigated in this research. To explore the performance of the immersion joint compression-bending loads are applied on a scaled specimen in specific patterns, which are designed based on a practical project. It is found that the extension and closure of the immersion joint vary non-linearly with applied axial forces. Fitting equations for axial stiffness are correspondingly given with regard to loading and unloading states of the joint. Under bending action the element edges which constitute the immersion joint still remain plane. Observed rotations of the joint are non-linearly increasing with bending moment, whether it is pushed forward or bend inversely. Hysteresis behavior obviously exists and the hysteretic loop tends to contract with the increase of the axial force. The stiffness ratio of the joint with respect to that of the tunnel element in service states ranges from 1/360 to 1/120 for the axial stiffness, and from 1/29 to 1/212 for the flexural stiffness.