矿用纤维增强沙漠砂混凝土拉伸力学性能试验研究

Experimental study on tensile mechanical properties of mine fiber reinforced desert sand concrete

混凝土作为现代锚网喷联合支护的重要组成部分,在控制地下矿山巷道围岩变形方面发挥着重要作用。针对传统矿用混凝土成本较高且在拉伸应力作用下容易出现开裂的实际问题,开发了一种使用沙漠砂作为细骨料,聚乙烯醇(PVA)纤维作为增强材料的新型矿用纤维增强沙漠砂混凝土。为验证该新型支护材料的力学性能,选取沙漠砂粒径、水胶比、纤维长度和纤维掺量作为变量,共制备尺寸为330 mm×60 mm×13 mm的狗骨试件36个,探讨其对混凝土弹性模量、抗拉强度、极限拉应变等性能的影响。研究结果表明,用沙漠砂替换普通河砂,材料的弹性模量和极限拉应变均呈现出增大的趋势,分别达到3.70 MPa和4.01%,新疆沙漠砂的优良性质得到充分发挥,为巷道支护等工程提供了更经济有效的选择。掺入国产PVA纤维能够有效增强沙漠砂混凝土的抗拉强度和变形能力。与河砂相比,沙漠砂粒径较小且表面光滑,使其在基体中分布较为均匀,能够提高混凝土抵抗裂缝能力,并且沙漠砂与PVA纤维之间的协同作用也更为有效,纤维能够更好地滑移,并抵抗裂纹的发展。沙漠砂属于中细砂,能够较好地与其他原材料发生作用。本文考虑到西部矿区沙漠砂资源丰富,研究开发的矿用纤维增强沙漠砂混凝土在西部沙漠矿区巷道支护领域具有一定的应用前景。

Concrete plays an important role in controlling the deformation of surrounding rock in underground mine tunnels as a key component of modern anchor net spraying combined support.To address the practical issues of high cost and susceptibility to cracking under tensile stress of traditional mine concrete,a new type of mine fiber reinforced desert sand concrete has been developed,which uses desert sand as fine aggregate and polyvinyl alcohol(PVA)fibers as reinforcement material.In order to verify the mechanical properties of the new supporting material,36 dog bone specimens with the size of 330 mm×60 mm×13 mm are prepared by selecting the particle size of desert sand,water-binder ratio,fiber length and fiber dosage as the variable,and their effects on the elastic modulus,tensile strength and ultimate tensile strain of concrete are discussed.The results show that the tensile elastic modulus and ultimate tensile strain of the material are increased by replacing ordinary river sand with desert sand,reaching 3.70 MPa and 4.01%,respectively,and the excellent properties of Xinjiang desert sand are fully utilized,which provides a more economical and effective choice for roadway support and other projects.The incorporation of domestic PVA fiber can effectively enhance the tensile strength and deformation capacity of desert sand concrete.Compared with river sand,desert sand has a smaller particle size and smooth surface makes it more evenly distributed in the matrix,which can improve the ability of concrete to resist cracks,and the synergy between desert sand and PVA fiber is also more effective,and the fiber can better slip and resist the development of cracks.Desert sand is a medium and fine sand,which can interact well with other raw materials.Considering the abundant desert sand resources in the western mining area,the research and development of mining fiber reinforced desert sand concrete has certain application prospects in the field of roadway support in the western desert mining area.