摘要
在膏体充填开采中,煤矸石-粉煤灰胶结充填材料(CGFB)可有效控制地表沉降。CGFB在被注入采空区后会受到水压影响和氯离子侵蚀。因此,研究水压和氯离子侵蚀对CGFB性能的影响对于实现有效的绿色开采至关重要。将CGFB试样在0、0.5、1.5或3.0 MPa的氯化钠溶液中浸泡15天,通过单轴压缩试验、声发射信号监测、数字散斑应变测量、扫描电子显微镜和X射线衍射研究了试样的力学性能和劣化机理。结果表明,随着浸泡压力的增加,试样单轴抗压强度先增大后减小。当浸泡压力从0 MPa增加到1.5 MPa时,平均单轴抗压强度增加了43.5%。当浸泡压力从1.5 MPa增加到3.0 MPa时,平均单轴抗压强度下降18.9%。此外,水压会促进氯离子进入CGFB内部并产生弗里德尔盐。较高的水压-氯盐耦合作用增加了CGFB的孔隙率,与0 MPa样品相比,3.0 MPa样品的孔隙率增加8.2%。高水压作用下,膏体充填体内部孔隙裂纹发育贯通,力学性能劣化,其密实度与抗压强度下降。
In paste backfill mining,cemented coal gangue-flyash backfills(CGFB)can effectively control surface subsidence.CGFBs are subjected to water pressure and chloride ion erosion in the gob.Therefore,an improved understanding of the influence of pressurized water and chloride salt erosion on the performance of CGFB is crucial for realizing effective green mining.In this study,CGFB samples were soaked in a NaCl solution at 0,0.5,1.5,or 3.0 MPa for 15 d.The mechanical properties of the samples and deterioration mechanisms were investigated using uniaxial compression tests,acoustic emission tests,digital speckle strain measurements,scanning electron microscopy,and X-ray diffraction.The results show that the uniaxial compressive strength(UCS)increased and then decreased with the increase of soaking pressure.When the soaking pressure increased from 0 to 1.5 MPa,the average UCS increased by 43.5%.Then,when the soaking pressure increased from 1.5 to 3.0 MPa,the average UCS decreased by 18.9%.Moreover,water pressure promotes chloride ions into the interior of CGFB and the production of Friedel's salt.Higher water pressureschloride salt erosion coupling increases the porosity of CGFB,with the 3.0 MPa sample showing an 8.2%increase in porosity compared to the 0 MPa sample.Thus,internal pore cracks developed and penetrated the samples,which degraded their mechanical properties and reduced their strength and compactness.
作者
李宗蓄
尹大伟
柳慧敏
谭毅
李学龙
LI Zong-xu;YIN Da-wei;LIU Hui-min;TAN Yi;LI Xue-long(State Key Laboratory of Mine Disaster Prevention and Control,Shandong University of Science and Technology,Qingdao 266590,China;State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,China;Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources,Henan Polytechnic University,Jiaozuo 454000,China)
基金
Projects(52274128, 51904167, 52174159) supported by the National Natural Science Foundation of China
Project supported by the Taishan Scholars Project Special Fund of Shandong Province,China
Project(KCF2204) supported by the Open Fund for the Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources,China
Project(22KF01) supported by the Open Fund for the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,China。
关键词
水压
氯盐侵蚀
煤矸石-粉煤灰充填
变形局部化带
声发射信号
细观形貌
water pressure
chloride salt erosion
coal gangue-flyash backfill
localized deformation zone
acoustic emission signal
fracture morphology
