Backfill mining technology is an inevitable choice for sustainable green mining. Full roof-contact of backfill is a key issue to ensure the long-term stability of the backfill mining technology, but no effective measures have been proposed. Based on the expansion characteristics of the modified magnesium slag-based filling material (MCM) and the shrinkage characteristics of the ordinary cement-bonded filling material (CFM), an active roof-contacted combined backfill mining technology (MCM-CFM) was proposed. The expansion characteristics and the uniaxial compressive strength (UCS) of the modified magnesium slag-based cementitious material (MC) were compared and analyzed. And the analytical expressions of the main control parameters as the axial force and the filling height of the backfill were derived, with or without lateral restraints. Then the sensitivity and the influence rule of the parameters were also investigated. The results show that: (1) the expansion rate of MC can reach 0.21% and increases rapidly in the early stage. At 28d and 40d, 84% and 95% of the total expansion deformation are reached, respectively, and the maximum expansion rate is 0.21%. (2) With or without lateral restraints, the height ratio of the upper and the lower filling parts is about 0.72 or 0.18, respectively. (3) The force subjected on the backfill is mainly controled by the parameters of the filling width, the elastic modulus and the expansion rate. (4) With or without lateral restraints, the height ratio of the two filling materials is controlled by the elastic modulus, the density or the elastic modulus, the Poisson’s ratio, the expansion rate, respectively. MCM-CFM can solve the problem of active roof-contact for backfill mining technology, and has the potential for large-scale application in mine backfilling.

中文翻译：

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基于改性镁渣基胶凝材料的主动接触顶板联合充填采矿技术


充填采矿技术是可持续绿色采矿的必然选择。充填体完全接触顶板是保证充填采矿技术长期稳定的关键问题，但目前尚未提出有效的措施。基于改性镁渣基充填材料（MCM）的膨胀特性和普通水泥结充填材料（CFM）的收缩特性，提出了主动顶板接触组合充填采矿技术（MCM-CFM）。对改性镁渣基胶凝材料（MC）的膨胀特性和单轴抗压强度（UCS）进行了比较和分析。推导了有或无侧向约束情况下回填体轴向力和充填高度等主要控制参数的解析表达式。然后考察了参数的敏感性和影响规律。结果表明：（1）MC的扩张率可达0.21%，且早期增长较快。 28d和40d时，分别达到总膨胀变形的84%和95%，最大膨胀率为0.21%。 (2)无论有无侧向约束，上、下填充部分的高度比分别约为0.72或0.18。 (3)回填体所受的力主要由填充宽度、弹性模量和膨胀率等参数控制。 (4)无论有或没有侧向约束，两种填充材料的高度比分别由弹性模量、密度或弹性模量、泊松比、膨胀率控制。 MCM-CFM可以解决充填采矿技术的主动接触顶板问题，在矿山充填中具有大规模应用的潜力。