Abstract: To investigate the deformation and failure characteristics of the anchor and soft surrounding rock in the soaked tunnel, two scale model tests are carried out based on the building Yangtze River bridge project at Jijiang. These two model tests are soaked state tunnel anchor model M2 and natural state tunnel anchor model M3. The reduced scale ratio is 1:30. By analysing the data from key measuring points, the deformation characteristics and rules of the tunnel anchor and its soft surrounding rock at different states are achieved. The results show that either on the surface or in the interior of the tunnel anchor, the measuring displacement of M2 is greater than that of M3, but the failure load value of M2 is lower than that of M3. There are various failure modes caused by different moisture contents. For model M2 with a moisture content of 7.39%, the cracks appear firstly at the surface of tunnel anchor hole and the west tunnel anchor, following at the ground surface and the east tunnel anchor. For model M3 with a moisture content of 5.36%, the cracks are initially observed at the ground surface of the upper part of the tunnel anchor, then at the side face of the tunnel anchorage hole and finally in other parts. Furthermore, the terrain also results in the deformation difference of tunnel anchorage with the same water content.

Key words: soft surrounding rock, tunnel anchorage, model test, soaked