循环冲击下胶结充填体动载力学特性试验研究
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摘要
矿山开采过程中,充填体将频繁受到开挖和爆破等动载的循环扰动,使充填体损伤与破坏具有显著的累积特性。因此,研究充填体循环冲击下的动载力学行为及特征对维持矿山结构及采场稳定具有重要的指导意义。论文采用SHPB对6组30个胶结充填体试件进行了单轴单次冲击及多次循环冲击试验,探索了充填体在不致使发生较大宏观破坏的冲击速度下多次循环冲击的应力应变、动载强度及变形破坏特征。研究发现:多次循环冲击下,充填体试件的应力应变曲线在到达动态峰值应力前后分别出现了1～2个低应力波峰,且相较于单次冲击下低应力波峰更为明显;多次循环冲击更有利于充填体内部微裂隙及孔隙在到达峰值应力前进行充分的压实及闭合,并可提高充填体最终破坏时的动载强度及承载能力,试件发生破坏时的最终动载强度及承载能力为单次冲击条件下的2倍左右;多次循环冲击下充填体的最终破坏形式为压裂破坏,其破碎程度较相近动载强度下单次冲击时低。
During the mining process, cemented tailings backfill bodies are disturbed frequently and repeatedly by cyclic dynamical loading such as excavation and blasting. This causes damage and failure to cemented tailings backfill body and make the failure process be of accumulative feature. In addition to research on statical mechanical properties of cemented tailings backfill, it's also necessary to study on dynamic behavior and characteristics of cemented tailings backfill under dynamic loading. This study conducted a series of Split Hopkinson Pressure Bar single and cyclic dynamic loading tests on cemented tailings backfill specimens, to discover the characteristic of stress-strain, dynamic strength, deformation and failure of cemented tailings backfill specimens. It is found that, compared with the stress-strain curves under a single impact, the stress-strain curves under cyclic impact loading show more evident 1～2 low stress peaks before reaching to the dynamic peak stress. Cyclic dynamic loading was more beneficial to make the microstructures and voids inside cemented tailings backfill specimens be compacted and closed before reaching to the dynamic peak stress. This also improved the dynamic strength and bearing capacity of cemented tailings backfill specimens. The dynamic peak stress value under a cyclic loading is approximately twice of that under single loading. The final failure mode of the cemented tailings backfill specimens under cyclic dynamic loading was fracturing, and the degree of damage was less than that under single loading under similar speeds.
During the mining process, cemented tailings backfill bodies are disturbed frequently and repeatedly by cyclic dynamical loading such as excavation and blasting. This causes damage and failure to cemented tailings backfill body and make the failure process be of accumulative feature. In addition to research on statical mechanical properties of cemented tailings backfill, it's also necessary to study on dynamic behavior and characteristics of cemented tailings backfill under dynamic loading. This study conducted a series of Split Hopkinson Pressure Bar single and cyclic dynamic loading tests on cemented tailings backfill specimens, to discover the characteristic of stress-strain, dynamic strength, deformation and failure of cemented tailings backfill specimens. It is found that, compared with the stress-strain curves under a single impact, the stress-strain curves under cyclic impact loading show more evident 1～2 low stress peaks before reaching to the dynamic peak stress. Cyclic dynamic loading was more beneficial to make the microstructures and voids inside cemented tailings backfill specimens be compacted and closed before reaching to the dynamic peak stress. This also improved the dynamic strength and bearing capacity of cemented tailings backfill specimens. The dynamic peak stress value under a cyclic loading is approximately twice of that under single loading. The final failure mode of the cemented tailings backfill specimens under cyclic dynamic loading was fracturing, and the degree of damage was less than that under single loading under similar speeds.
引文
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[10]李娜,周科平,潘东,等.中深孔爆破动载荷下块石充填体强度响应研究[J].矿冶工程,2011,31(4):9-13.LI Na,ZHOU Keping,PAN Dong,et al.Study on intensity response of rubble backfill to dynamic loading of medium-length hole blasting[J].Mining and Metallurgical Engineering,2011,31(4):9-13.
[11]张钦礼,杨伟,杨珊,等.动载下高密度全尾砂胶结充填体稳定性试验研究[J].中国安全科学学报,2015,25(3):78-82.ZHANG Qinli,YANG Wei,YANG Shan,et al.Test research on stability of high density total tailing cemented backfilling under dynamic loading[J].China Safety Science Journal,2015,25(3):78-82.
[12]CHEN Rongjun,LIU Hongwei,ZENG Rui.SHPBdynamic experiment on silica fume concrete[J].Advanced Materials Research,2013,631(1):771-775.
[13]FAIRHURST C E,HUDSON J A.Draft ISRM suggested method for the complete stress-strain curve for intact rock in uniaxial compression[J].International Journal of Rock Mechanics and Mining Sciences,1999,36(3):279-289.
[14]许金余,范建设,吕晓聪,等.围压条件下岩石的动态力学特性[M].西安:西北工业大学出版社,2012:56-58.
[15]付建新,杜翠凤,宋卫东.全尾砂胶结充填体的强度敏感性及破坏机制[J].北京科技大学学报,2014(9):1149-1157.FU Jianxin,DU Cuifeng,SONG Weidong.Strength sensitivity and failure mechanism of full tailings cemented backfills[J].Journal of University of Science and Technology Beijing,2014(9):1149-1157.
[2]HASSANIFP,MORTAZAVIA,SHABANIM.An investigation of mechanisms involved in backfill-rock mass behaviour in narrow vein mining[J].Journal of the South African Institute of Mining and Metallurgy,2008,108(8):463-472.
[3]RANKINER,PACHECOM,SIVAKUGANN.Underground mining with backfills[J].Soils and Rocks,2007,30(2):93-101.
[4]董凯程.爆破地震对充填体影响与控制技术研究[D].长沙:中南大学,2010.
[5]董璐,高谦,南世卿,等.超细全尾砂新型胶结充填料水化机理与性能[J].中南大学学报(自然科学版),2013,44(4):1571-1577.DONG Lu,GAO Qian,NAN Shiqing,et al.Performance and hydration mechanism of new super fine cemented whole-tailings backfilling materials[J].Journal of Central South University(Natural Science),2013,44(4):1571-1577.
[6]孙吉书,窦远明,周戟,等.应变速率对混凝土抗压特性影响的试验研究[J].混凝土与水泥制品,2011(5):1-3.SUN Jishu,DOU Yuanming,ZHOU Ji,et al.Experimental study on the affect to compressive property of concrete caused by strain rate[J].China Concrete and Cement Products,2011(5):1-3.
[7]严成,欧卓成,段卓平,等.脆性材料动态强度应变率效应[J].爆炸与冲击,2011,31(4):423-427.YAN Cheng,OU Zhuocheng,DUAN Zhuoping,et al.Strain-rate effects on dynamic strength of brittle materials[J].Explosion and Shock Waves,2011,31(4):423-427.
[8]闫东明,林皋,王哲,等.不同应变速率下混凝土直接拉伸试验研究[J].土木工程学报,2005(6):97-103.YAN Dongming,LIN Gao,WANG Zhe,et al.A study on direct tensile properties of concrete at different strain rates[J].China Civil Engineering Journal,2005(6):97-103.
[9]刘志祥,李夕兵.爆破动载下高阶段充填体稳定性研究[J].矿冶工程,2004,24(3):22-24.LIU Zhixiang,LI Xibing.Research on stability of high-level backfill in blasting[J].Mining and Metallurgical Engineering,2004,24(3):22-24.
[10]李娜,周科平,潘东,等.中深孔爆破动载荷下块石充填体强度响应研究[J].矿冶工程,2011,31(4):9-13.LI Na,ZHOU Keping,PAN Dong,et al.Study on intensity response of rubble backfill to dynamic loading of medium-length hole blasting[J].Mining and Metallurgical Engineering,2011,31(4):9-13.
[11]张钦礼,杨伟,杨珊,等.动载下高密度全尾砂胶结充填体稳定性试验研究[J].中国安全科学学报,2015,25(3):78-82.ZHANG Qinli,YANG Wei,YANG Shan,et al.Test research on stability of high density total tailing cemented backfilling under dynamic loading[J].China Safety Science Journal,2015,25(3):78-82.
[12]CHEN Rongjun,LIU Hongwei,ZENG Rui.SHPBdynamic experiment on silica fume concrete[J].Advanced Materials Research,2013,631(1):771-775.
[13]FAIRHURST C E,HUDSON J A.Draft ISRM suggested method for the complete stress-strain curve for intact rock in uniaxial compression[J].International Journal of Rock Mechanics and Mining Sciences,1999,36(3):279-289.
[14]许金余,范建设,吕晓聪,等.围压条件下岩石的动态力学特性[M].西安:西北工业大学出版社,2012:56-58.
[15]付建新,杜翠凤,宋卫东.全尾砂胶结充填体的强度敏感性及破坏机制[J].北京科技大学学报,2014(9):1149-1157.FU Jianxin,DU Cuifeng,SONG Weidong.Strength sensitivity and failure mechanism of full tailings cemented backfills[J].Journal of University of Science and Technology Beijing,2014(9):1149-1157.