Effect of lining thickness lack on lining safety for highway tunnel

The calculation models of lining thickness lack were set up for surrounding rock Ⅲ and rock Ⅳ. The internal forces and safety factors of tunnel lining at various locations were compared under the conditions of tunnel linings with disease and without disease. Using numerical methods, the effect of lining thickness lack caused by disease extent and range on lining safety were analyzed. Analysis result shows that the values of the bending moments, shears and axial forces at the wall, haunch and vault of lining are large, so these sections are belonging to the sensitive parts to disease. When thickness lack disease appears, the safety factor of tunnel lining significantly reduces. With the increase of disease degree, the safety factor of left wall linearly decreases, but the safety factors of haunch and vault curvily reduce. With the increase of disease width, the safety factor firstly decreases obviously and then increases in small range, but the overall trend is decrescent. With the transfer of disease region from wall to vault, the influenced region of lining increases gradually.