Model tests on segmental subway tunnel crossing ground fissure belt

By use of a 1:25 model to simulate one section of the ground fissure in Xi'an, the effect of ground fissure activities on segmental lining is studied. The results indicate that each segment of lining can satisfy the quantitative unattached deformation and there is very small effect between each segment lining, so it can adapt to the ground fissure surroundings. When a fissure moves, the earth pressure at the lining top at the depth of 10 cm of two segments in the hanging wall and one segment in the footwall near the fissure decreases. The earth pressure at the lining bottom at the depth of 5 cm of one segment in the hanging wall near the fissure decreases, but that in the footwall increases. The top and bottom of two segment linings near the fissure in the hanging wall are longitudinally pressed. The top of one segmental lining in the footwall is pulled, but its bottom is pressed. Both sides of the lining near the fissure in the hanging wall are pressed, and the effect is smaller in the footwall. The main failure mode for the linings is that sidewall suffers hoop extrusion, which often occurs in the hanging wall, especially near the fissure. The secondary fissures in the soil do not develop, and they only appear on the top of the hanging wall near the fissure and inside the soil of the footwall. The soil is pulled and sheared to form the fissure.