| At present, the problems of the underground support structure in soft rock tunnels have not been well solved. Tunnels in these kind of rocks, the rock pressure fluctuates significantly. These tunnels often have large amount of deformation, and may be badly damaged. It has a negative effect on improving the economic benefit and on working safety. Therefore, the research work on finding effective underground supporting method in soft rock tunnels is urgently needed. In this paper, a new U-steel and Fiber Reinforced Concrete support system were developed to solve this problem. This kind of combination support can completely change the weakness of the metal bracket witch can easily get a destabilization failure. By the experiment method, the mechanics properties of the concrete with different acrylic fiber content were investigated, and the optimized concrete mix was found. Based on the experimental data, two EFM models of support structures of U-steel bracket with and without fiber reinforced concrete are investigated and compared. This new underground support method was applied in transport tunnel ofâ…¢2 mining district in Daihe Coal Mine. Numerical simulation and on-site inspection shows that:1. acrylic fiber can improve the ductility of the concrete, make the concrete have good deformation capacity. And it can be used in the soft rock tunnel support structures.2. The U29 metal support can afford a line load of 88kN/m,before it starts to buckle.3. The bearing capacity of U-steel bracket with fiber reinforced concrete are 3.6 times more than of the U-steel bracket without fiber reinforced concrete.
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