多源煤基固废充填体固结与承载性能的温度效应研究

Research on temperature effect of consolidation and bearing capacity of multi-source coal-based solid waste backfill

为研究煤基固废膏体充填体在煤矿深部高地温环境下的固结承载性能,采用单轴压缩和声发射试验,测试不同养护温度(20、35、50℃)和龄期(3、7、14、28 d)影响下膏体充填体强度与破坏特征;通过SEM测定充填胶结体微观形貌和矿物组成,从微观角度揭示养护温度对水化反应的影响规律。研究结果表明:伴随养护温度的升高,其对水化反应的影响逐渐从促进转变为抑制,28 d抗压强度在养护温度为35℃时达到最大值;声发射事件主要发生在压密和破坏阶段,养护温度提高促使声发射活动提前活跃,充填体破坏形态逐渐由延性破坏转变为脆性破坏;由于热损伤作用,高温养护加快了充填体早期水化反应速率,而对养护后期充填体内C-S-H和孔隙结构造成破坏,对其长期强度的增加产生不利影响。

In order to study the consolidation bearing capacity of coal-based solid waste paste backfill in deep high ground temperature environment of coal mine,uniaxial compression and acoustic emission tests were used to test the strength and failure characteristics of paste backfill under different curing temperature conditions(20℃,35℃and 50℃)and ages(3 d,7 d,14 d and 28 d).The microstructure and mineral composition of the filling cement were measured by SEM,and the influence of curing temperature on the hydration reaction was revealed from the microscopic point of view.The results show that:with the increase of curing temperature,its influence on hydration reaction gradually changes from promotion to inhibition,and the 28 d compressive strength reaches the maximum at 35℃;acoustic emission events mainly occur in the compaction and failure stages.The increase of curing temperature promotes the activity of acoustic emission in advance,and the failure mode of filling body gradually changes from ductile failure to brittle failure;due to the thermal damage,high temperature curing accelerates the early hydration reaction rate of the filling body,and causes damage to the C-S-H and pore structure of the filling body in the later stage of curing,which has an adverse effect on the increase of its long-term strength.