高应力破碎镍矿机械化湿喷混凝土配合比优化

Mix Optimization of Mechanized Wet Shotcrete in High-stress Fractured Nickel Mine

针对金川镍矿矿岩破碎,地压较大,采用传统的干喷锚网支护效果不理想且巷道返修率高的问题,提出湿喷混凝土技术来改善这一局面。采用正交设计方法进行配合比试验,研究了水灰比、水泥、减水剂和砂石比（细砂与绿豆石的质量比）对湿喷混凝土工作性及力学性能的影响规律。结果表明：各因素对湿喷混凝土工作性的影响顺序为：水灰比＞水泥掺量＞砂石比＞减水剂掺量,要保证湿喷料浆塌落度大于150 mm,其水灰比应大于0．44、水泥掺量应大于430 kg/m3、砂石比应在2～4；水泥掺量对湿喷混凝土的力学特性影响最大,其次为水灰比,砂石比与湿喷混凝土强度呈凸形关系,减水剂对湿喷混凝土的强度影响较小。引入单位价值强度系数V对不同水泥掺量湿喷混凝土的经济性进行对比,确定了最佳配合比,通过现场应用达到了较好的效果,具有较高的综合经济效益。

For solving the problems of poor supporting effect,high repair rate of the traditional dry shotcrete-rockbolt-mesh support in Jinchuan nickel mine,which is fractured and under high geo-pressure,the wet shotcrete technology is adopted to make the situation better. The effects of water-cement ratio,cement,water reducer and sand-coarse aggregate ratio（ fine mung bean stone mass ratio） on workability and mechanical properties of wet shotcrete are studied in mix proportion experiment by u-sing orthogonal design. The results show the effect sequence as following：water-cement ratio〉cement dosage〉sand-coarse ag-gregate ratio〉 water reducer dosage. And,water-cement ratio greater than 0. 44,cement dosage greater than 430 kg/m3 ,a 2～4 sand-coarse aggregate ratio are necessary to acquire a slurry with a slump greater than 150 mm. Cement dosage is the biggest influence on the mechanical properties of wet shotcrete,followed by water-cement ratio and water reducer in sequence. The re-lationship curve between sand-coarse aggregate ratio and strength of wet shotcrete is a convex curve. The economical efficiency of wet shotcrete with different cement dosages is researched by introducing the concept of the coefficient of strength per unit cost V. Finally,the optimum mix proportion is determined. The application of the wet shotcrete achieves good effect and higher comprehensive economic benefit.