Full-scale tests on deformation recoverability of longitudinal joints of shield tunnel

A series of full-scale tests are conducted on the two-seam longitudinal joint at the shield tunnel crown and one-seam longitudinal joint at the shield tunnel waist, aiming to explore the deformation development laws of these two joints under the surcharge above the tunnel and the deformation recoverability under the conditions of unloading and soil micro-disturbance grouting. The test results show that the joint opening develops nonlinearly with the increase of the surcharge load. The deformation caused by the surcharge can be partially recovered by unloading. The smaller the deformation, the better the recovery effects. Under the action of grouting, the deformation recovery effects of the joints at the tunnel crown are better than those of the joints at the tunnel waist.