寒冷期湿喷混凝土温度影响效应与纤维掺量优化

为解决金英金矿寒冷期湿喷支护效果不佳的问题，对其性能影响因素进行了分析，认为低温与不合理的纤维掺量是主要问题所在。对养护温度分别为0，6，13，20 ℃的不同龄期混凝土试块进行了强度测试及表面特征电镜扫描(SEM)分析，并通过混凝土水化反应过程对上述分析进行了解释；基于圆盘测试试验（RDP试验），对不同类型与掺量的合成纤维混凝土圆盘试件荷载 挠度 能量曲线进行分析，优选出了能够满足该矿地下巷道支护要求的纤维；针对温度影响试验及RDP试验结果，在现场进行了应用研究。结果表明:在将井下温度控制在10 ℃以上且向混凝土中添加6 kg·m^-3的C类纤维情况下，湿喷支护后混凝土回弹率明显降低，巷道准入作业时间大幅缩短且湿喷混凝土的单轴抗压强度平均值可达30 MPa，完全满足金英金矿的支护要求。

Temperature Effects of Wet Shotcrete and Optimization of Fiber Content During Cold Period

In order to solve the problem of poor effect of wet shotcrete support of Jinying gold mine during cold period, the factors affecting its performance were analyzed, and it was considered that low temperature and unreasonable fiber ratio were the main problems. The strength tests and surface characteristics scanning electron microscope (SEM) analysis of concrete specimens were carried out under curing temperature 0, 6, 13, 20 ℃, respectively, and the above analysis was explained by the hydration reaction of concrete. Based on RDP experiment, the load deflection energy curves of different types of concrete disc specimens with different contents of synthetic fibers were analyzed, and the fibers which could meet the requirement of underground roadway support of the mine was optimized. According to the experiments of temperature influence and the results of RDP experiment, the applied research was carried out on the spot. The results show that the rebound rate of concrete after wet shotcrete is obviously reduced when the underground temperature is controlled above 10 ℃ and the C fiber (6 kg·m^-3) is added to concrete. The operation time of roadway access is greatly shortened, and the uniaxial compressive strength of wet shotcrete can reach 30 MPa. The method can fully meet the support requirements of Jinying gold mine.