软弱围岩隧道钢纤维混凝土衬砌承载特性模型试验研究

为满足软弱围岩隧道开挖后尽快封闭岩面、适应一定变形及提供足够支护力的要求,通过素混凝土、钢筋混凝土及钢纤维混凝土衬砌力学行为室内模型试验,对钢纤维混凝土衬砌的承载特性进行研究。研究结果表明:钢纤维混凝土衬砌初裂荷载提高了20%,极限荷载得到较大提高;掺入钢纤维后衬砌结构韧性增强,初裂后仍能抵抗一定变形并较大降低变形速率,与素混凝土、钢筋混凝土相比可承受更大的变形;钢纤维混凝土衬砌初裂后承载特性曲线缓慢上升,至2倍初裂荷载时仍无收敛迹象,素混凝土快速收敛,钢筋混凝土在一定缓慢上升后快速趋于收敛,软弱围岩条件下,钢纤维混凝土初支在一定变形后可与围岩特征曲线相交,达到围岩–结构稳定状态,是一种力学性能良好的快速支护材料。研究成果对软弱围岩隧道的设计与施工都具有重要的意义。

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.