煤矸石击实特性试验

Compaction Characteristics of Coal Gangue

天然煤矸石级配极不均匀,多变量控制下的击实特性试验研究对其合理利用有着重要意义。以广西合山市某煤矸石堆为例,现场筛分得到该煤矸石堆天然矸石级配曲线,并设计了5种人工级配试验样进行击实试验,得到不同级配煤矸石的最佳含水率和最大干密度。测试了不同击实数(不同击实能量)作用下煤矸石的破碎值及休止角等指标参数。研究表明:煤矸石击实性受含水率、颗粒级配和击实能量等因素影响,大于5mm的粗颗粒质量分数(P_5)为70%时击实效果最佳;随着粗颗粒含量的增加,击实最优含水率由P_5=10%的8%降低为P_5=70%的4%;煤矸石击实过程可以简化为3个阶段:初期的颗粒间压密、中期的颗粒破碎和后期的弹性回弹,击实破碎可以有效地改善其散体的级配条件,在填筑工程施工过程中,应确保单位体积击实能量不小于437kJ/m3;煤矸石休止角与颗粒级配及击实程度关系密切,P_5=70%时煤矸石休止角最大。

The grading of natural coal gangue is extremely uneven, and the study of compaction test under the control of multivariate analysis has great significance for its rational utilization. This study takes a cer- tain coal gangue heap in Heshan ,Guangxi, as an example to obtain a grading curve of natural coal gangue in the heap by local sieving. Five experimental samples of man-made grading were designed for the compac- tion test, which obtained the best moisture content and maximum dry density of different graded coal gangue. Also the index parameters of crushing value angle of the repose were tested under the action of different grading. The study shows that the compaction property of coal gangue is affected by moisture content, grain composition and compaction energy. When the content of coarse particles larger than 5mm reaches its peak at 70 %, the compaction effect is optimal. With the increase of coarse content, the optimal moisture content of compaction decreases from 8% of P5 = 10% to 4% of P5=70%. The compaction pro- cedure of coal gangue can be classified into three steps： the initial step pf compact; the middle stage of breakage, and the later stag of elastic rebound. The breakage can effectively improve the graded condition of bulk solid. It should be assured that the compaction energy per unit volume is no less than 437 kJ/m^3 when the filling engineering is carried out. The repose angle has close relationship with grain composition and compaction level, when P5 equals 70%, and the angle of coal gangue reaches its maxim.