Abstract
In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as the reference group. The static mechanical properties, dynamic mechanical properties, and crack failure characteristics of the hybrid fiber concrete were experimentally studied. The test results showed that compared to the reference group concrete, the compressive strength of the hybrid fiber-reinforced concrete did not significantly increase, but the splitting tensile strength increased by 60.4%. The split Hopkinson compression bar results showed that the optimal group peak stress and peak strain of the hybrid fiber concrete increased by 58.2% and 79.2%, respectively, and the dynamic toughness increased by 68.1%. The strain distribution before visible cracks was analyzed by the DIC technology. The results showed that the strain dispersion phenomenon of the fiber-reinforced concrete specimen was stronger than that of the reference group concrete. By comparing the crack failure forms of the specimens, it was found that compared to the reference group concrete, the fiber-reinforced concrete specimens showed the characteristics of continuous and slow ductile failure. The above results suggest that HFRC has significantly high dynamic splitting tensile strength and compressive deformation capacity, as well as a certain anti-disturbance effect. It is an excellent construction material for deep mines under complex working conditions.
Highlights
In order to ensure a working energy supply, China’s coal mining has been gradually promoted to the deep rock strata [1,2,3]
In order to improve the mechanical properties of the shaft lining concrete, the authors of this study focused on the C60 concrete, which is commonly used in shaft lining, and prepared hybrid fiber concrete by adding steel and polypropylene fibers
Length–Diameter of this focused on the C60 Ratio concrete, which is commonly used in shaft lining,Ratio and prepared hybrid fiber concrete by adding steel and polypropylene fibers.46.7
Summary
In order to ensure a working energy supply, China’s coal mining has been gradually promoted to the deep rock strata [1,2,3]. In a certain range of mining operation space/coal strata, underground aquifers will be deformed, broken, and moved, resulting in a large amount of cracks, surface settlement, and stress and strain fields [4,5,6]. As the most widely used vertical passage component in underground mines, the strength requirements of shaft lining, which is mainly composed of high-strength concrete, are becoming more and more severe. Studies by many experts and authors have shown that the incorporation of fiber into concrete can effectively solve its problems of poor crack and impact resistance, as well as increase its stress strength [9]. Steel fiber concrete (SFRC) has been widely used for its superior mechanical and deformation properties [10]
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