Study On Mechanical Characteristics Of Steel Fiber Reinforced Shotcrete Lining

With the increase of mining depth, the support of deep roadway has become a major technical problem. Based on the theory of modern bolting, spray layer plays an important role. In order to improve the mechanical properties of shotcrete and supporting effect, this paper studied the mechanical properties of steel fiber reinforced concrete sprayed.Firstly, this papers simplified model for straight wall and semicircle arch spray layer lining which is commonly used, through the analysis of the internal force for the lining, deduce the shear, axial force and moment expressions of arbitrary cross section for the spray layer, in this way, the internal force distribution of the spray layer structure is intuitively shown up. And by the spraying steel fiber concrete mixture ratio test, the steel fiber optimum content of40Kg/m3is gained.Then, models were designed according to the similarity theory, and spray steel fiber concrete lining is researched through the test, the results show that in the plain concrete mixed with steel fiber, the support strength of the structure is improveed. After specimens begin to crack, its width expands with the increase of load, when they reach the ultimate strength, the unloading phenomenon appear slowly with the crack continues to expand, rather then become suddenly broken or broken as plain concrete. Sprayed steel fiber reinforced concrete specimens cracks are still able to withstand the load when cracks appear, and damaged parts are quite complete. These account for that steel fiber concrete has good crack resistance and toughness, and show that steel fiber reinforced concrete lining has better ability to let the compressive deform. Therefore, it is suitable for the supporting of deep buried tunnel and soft rock roadway.Finally, the results through the numerical simulation show that, for straight wall and semicircle arch lining structure of sprayed steel fiber reinforced concrete, as a general rule, when put distributed load on the scope of entire arch, the damage appear from vaults or shoulder, and when put the same load on the whole arch and straight wall, the damage start from the straight wall or the junction of straight wall and the arch, this phenomenon are basically identical with the experimental results. In this paper, the research results may provide the reference for the application of sprayed steel fiber reinforced concrete lining structure in deep buried tunnel and soft rock roadway.