某矿山素喷支护体早期强度特征与适用性分析

Early strength characteristics and applicability analysis of plain shotcrete support of a mine

针对某矿山素喷支护体在开采扰动条件下易开裂脱落的问题,对现有支护体进行了单轴抗压强度试验,分析现有支护体强度特征及其与速凝剂用量、水用量的关系。在此基础上,通过现场应力监测,研究巷道顶板与帮部径向次生压应力特征,并对素喷支护体适用性进行了分析。研究结果表明:由采场开采所诱发的巷道顶板径向次生压应力大于巷道帮部径向次生压应力。现有素喷支护体单轴抗压强度小于巷道径向次生压应力是导致现有素喷支护体破坏的主要原因。现有素喷支护体强度随水用量的增大呈现先增大而后减小的趋势,随速凝剂用量的增大而减小,并且相对于未添加速凝剂的支护体,现有支护体强度损失约73.6%。减少速凝剂用量至现用量40%或增大水用量至现用量的1.30倍,素喷支护体单轴抗压强度将大于巷道径向次生压应力,有利于提升素喷支护体抵抗采场开采所诱发的次生应力的能力。

Aiming at the problem that the plain shotcrete support of a mine is easy to crack and fall off under the condition of mining disturbance,the uniaxial compressive strength test of the existing support is carried out,the strength characteristics of the existing support and its relationship with the amount of accelerator and water consumption are analyzed.On this basis,through on-site stress monitoring,the characteristics of radial secondary compressive stress of roadway roof and side are studied,and the applicability of plain shotcrete support is analyzed.The results show that the radial secondary compressive stress of roadway roof induced by stope mining is greater than that of roadway side. The uniaxial compressive strength of the existing plain shotcrete support is less than the radial secondary compressive stress of the roadway, which is the main reason for the failure of the existing plain shotcrete support. The strength of the existing plain shotcrete support increases first and then decreases with the increase of water consumption, and decreases with the increase of the amount of accelerator. Compared with the support without accelerator, the strength loss of the existing support is about 73.6%. Reducing the amount of accelerator to 40% of the current amount or increasing the water consumption to 1.30 times the current amount, the uniaxial compressive strength of the plain shotcrete support will be greater than the radial secondary compressive stress of the roadway, which is conducive to improving the ability of the plain shotcrete support to resist the secondary stress induced by the mining of the stope.