Model tests on bearing characteristics of steel fiber-reinforced concrete lining of weak surrounding rock tunnel

In order to meet the requirements of weak surrounding rock tunnel to close rock surface as soon as possible after excavation, to adapt to a certain deformation and to provide sufficient supporting force, through the indoor model tests on the mechanical behaviors of linings of plain concrete, reinforced concrete and steel fiber-reinforced concrete, the bearing characteristics of steel fiber-reinforced concrete lining are studied. The results show that the initial cracking load of the steel fiber-reinforced concrete lining increases by 20%, and the ultimate load is greatly improved. The toughness of lining structure is enhanced after mixing steel fiber, the lining structure can still resist certain deformation and reduce the deformation rate greatly after initial cracking, and it can bear greater deformation as compared with the plain concrete and the reinforced concrete. The bearing characteristic curve of steel fiber-reinforced concrete lining rises slowly after the initial cracking, while that of the plain concrete has a rapid convergence, and that of the reinforced concrete exhibits rapid convergence after slow rise. Owing to the weak surrounding rock, the initial support of steel fiber-reinforced concrete can intersect with the characteristic curve of the surrounding rock after a certain deformation so as to reach the stable state of surrounding rock and structure. The study results are of important significance to the design and construction of weak surrounding rock tunnel.