湿喷混凝土配合比优化试验

Optimization Experiment on Mixing Ratio of Wet Shotcrete

针对锦丰金矿破碎、易风化的围岩条件及钢网支护存在的问题,进行了湿喷混凝土配合比优化现场试验,研究了关键物料掺量对湿喷混凝土单轴抗压强度的影响规律。结果表明:增加水泥掺量,可以显著提高湿喷混凝土单轴抗压强度,且水泥掺量达430 kg/m3时,湿喷混凝土强度足以保证围岩稳定;塑料纤维的掺量由1 kg/m3提高到3,5 kg/m3时,湿喷混凝土单轴抗压强度先提高后降低;在保持湿喷混凝土料浆可泵送性不变的前提下,增加减水剂的掺量,可以显著提高湿喷混凝土的单轴抗压强度;当液体速凝剂掺量增加时,混凝土7,28 d单轴抗压强度均会降低。最后,提出了抗压经济强度指数的概念,以此为依据优化了湿喷混凝土配合比,应用于现场施工并获得良好支护效果,为国内矿山喷射混凝土支护提供了借鉴。

According to the crushing and easy weathering surrounding rock situation and the problems of stencil supporting of Jinfeng gold mine,the optimization experiment on the mixing ratio of wet shotcrete is conducted so as to analyze the influence rule of the key material content to the uniaxial compressive strength of wet shotcrete. The experiment results show that,the uniaxial compressive strength of wet shotcrete can be improved by increasing dosage of cement,the surrounding rock stability can be ensured by the wet shotcrete with the cement content is 430 kg / m^3. If the plastic fiber content is changed from 1 ~ 3 and 5 kg / m^3,the uniaxial compressive strength will tend to increase firstly and then decrease.The uniaxial compressive strength of wet shotcrete can be increased significantly by increasing the dosage of water reducing agent under the condition of remaining the pumping properties of the wet shotcrete slurry unchanged. The uniaxial compressive strength of 7 d and 28 d can be decreased by increasing the liquid accelerator dosage. Besides that,the concept of compressive strength economic strength index is proposed,the mixing ratio of wet shotcrete is optimized based on the concept,so good supporting effect is obtained and it can provide some references for shotcrete supporting of the mines in our country.