In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under...In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include:(1)drained and undrained conditions,(2) different filling rates,(3) different filling sequences, and(4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under stress.Furthermore, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.展开更多
The stability of cemented paste backfill(CPB)is threatened by dynamic disturbance,but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose.Therefore,a split Hopkinso...The stability of cemented paste backfill(CPB)is threatened by dynamic disturbance,but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose.Therefore,a split Hopkinson pressure bar(SHPB)was utilized to investigate the high strain rate compressive behavior of CPB with dynamic loads of 0.4,0.8,and 1.2 MPa.And the failure modes were determined by macro and micro analysis.CPB with different cement-to-tailings ratios,solid mass concentrations,and curing ages was prepared to conduct the SHPB test.The results showed that increasing the cement content,tailings content,and curing age can improve the dynamic compressive strength and elastic modulus.Under an impact load,a higher strain rate can lead to larger increasing times of the dynamic compressive strength when compared with static loading.And the dynamic compressive strength of CPB has an exponential correlation with the strain rate.The macroscopic failure modes indicated that CPB is more seriously damaged under dynamic loading.The local damage was enhanced,and fine cracks were formed in the interior of the CPB.This is because the CPB cannot dissipate the energy of the high strain rate stress wave in a short loading period.展开更多
对煅烧硬质高岭土对铅锌矿溢流尾砂胶结膏体充填材料抗压强度的影响进行了研究。研究结果表明:当胶结剂中煅烧硬质高岭土(Calcined Hard Kaolin,CHK)取代水泥率从0增加到30%时,胶结膏体充填材料(Cemented Paste Backfill,CPB)28d抗压强...对煅烧硬质高岭土对铅锌矿溢流尾砂胶结膏体充填材料抗压强度的影响进行了研究。研究结果表明:当胶结剂中煅烧硬质高岭土(Calcined Hard Kaolin,CHK)取代水泥率从0增加到30%时,胶结膏体充填材料(Cemented Paste Backfill,CPB)28d抗压强度基本保持不变;当CHK取代水泥率从30%增加到80%时,CPB的28d抗压强度急剧降低;当CHK取代水泥率低于50%的CPB养护到28d或56d后,其抗压强度大幅度降低;当CHK取代水泥率为50%的CPB养护到180d时,其抗压强度呈增长趋势。CPB抗压强度损失与其内部形成膨胀性物质(石膏)有关。当CHK取代水泥率为50%时,由于降低了胶结剂中水泥熟料的量,CHK中偏高岭土(Metakaolin,MK)和水泥水化产物氢氧化钙的火山灰反应解除或减少了膨胀性二水石膏的形成,结果CPB的180d抗压强度呈增长趋势。展开更多
基金the Natural Sciences and Engineering Research Council of Canada (NSERC)the University of Ottawa
文摘In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include:(1)drained and undrained conditions,(2) different filling rates,(3) different filling sequences, and(4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under stress.Furthermore, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.
基金supported by the National Key R&D Program of China(No.2017YFC0602902)the National Natural Scienceof China(Nos.41807259 and 51874350)+2 种基金the Fundamental Research Funds for the Central Universities of Central South University(No.2016zztx096)The support provided by the China Scholarship Council(CSC)during the visit of the first author toécole Polytechnique de Montréal(Student ID:201706370039)the materials supply by Fan Kou lead-zinc mine of Shenzhen Zhongjin Lingnan Non-ferrous metal Company Limited。
文摘The stability of cemented paste backfill(CPB)is threatened by dynamic disturbance,but the conventional low strain rate laboratory pressure test has difficulty achieving this research purpose.Therefore,a split Hopkinson pressure bar(SHPB)was utilized to investigate the high strain rate compressive behavior of CPB with dynamic loads of 0.4,0.8,and 1.2 MPa.And the failure modes were determined by macro and micro analysis.CPB with different cement-to-tailings ratios,solid mass concentrations,and curing ages was prepared to conduct the SHPB test.The results showed that increasing the cement content,tailings content,and curing age can improve the dynamic compressive strength and elastic modulus.Under an impact load,a higher strain rate can lead to larger increasing times of the dynamic compressive strength when compared with static loading.And the dynamic compressive strength of CPB has an exponential correlation with the strain rate.The macroscopic failure modes indicated that CPB is more seriously damaged under dynamic loading.The local damage was enhanced,and fine cracks were formed in the interior of the CPB.This is because the CPB cannot dissipate the energy of the high strain rate stress wave in a short loading period.
文摘对煅烧硬质高岭土对铅锌矿溢流尾砂胶结膏体充填材料抗压强度的影响进行了研究。研究结果表明:当胶结剂中煅烧硬质高岭土(Calcined Hard Kaolin,CHK)取代水泥率从0增加到30%时,胶结膏体充填材料(Cemented Paste Backfill,CPB)28d抗压强度基本保持不变;当CHK取代水泥率从30%增加到80%时,CPB的28d抗压强度急剧降低;当CHK取代水泥率低于50%的CPB养护到28d或56d后,其抗压强度大幅度降低;当CHK取代水泥率为50%的CPB养护到180d时,其抗压强度呈增长趋势。CPB抗压强度损失与其内部形成膨胀性物质(石膏)有关。当CHK取代水泥率为50%时,由于降低了胶结剂中水泥熟料的量,CHK中偏高岭土(Metakaolin,MK)和水泥水化产物氢氧化钙的火山灰反应解除或减少了膨胀性二水石膏的形成,结果CPB的180d抗压强度呈增长趋势。
