Pre-stressed bolt anchorage is the key technology for jointed rock masses in rock tunnelling,slope treatment and mining engineering.To investigate the mechanical properties and reinforcement effect of jointed rock mas...Pre-stressed bolt anchorage is the key technology for jointed rock masses in rock tunnelling,slope treatment and mining engineering.To investigate the mechanical properties and reinforcement effect of jointed rock masses with pre-stressed bolts,in this study,uniaxial compression tests were conducted on specimens with different anchoring types and flaw inclination angles.ABAQUS software was used to verify and supplement the laboratory tests.The laws of the uniaxial compressive strength(UCS)obtained from the numerical simulations and laboratory tests were consistent.The results showed that under the same flaw angle,both the UCS and elastic modulus of the bolted specimens were improved compared with those of the specimens without bolts and the improvements increased with an increase in the bolt pre-stress.Under the same anchoring type,the UCS and elastic modulus of the jointed specimens increased with an increase in the flaw angle.The pre-stressed bolt could not only restrain the slip of the specimens along the flaw surface but also change the propagation mode of the secondary cracks and limit the initiation of cracks.In addition,the plot contours of the maximum principal strain and the Tresca stress of the numerical models were influenced by the anchoring type,flaw angle,anchoring angle and bolt position.展开更多
Rockburst disasters occur frequently during deep underground excavation,yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions.Consequently,rockburst control...Rockburst disasters occur frequently during deep underground excavation,yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions.Consequently,rockburst control remains challenging in the engineering field.In this study,the mechanism of excavation-induced rockburst was briefly described,and it was proposed to apply the excavation compensation method(ECM)to rockburst control.Moreover,a field test was carried out on the Qinling Water Conveyance Tunnel.The following beneficial findings were obtained:Excavation leads to changes in the engineering stress state of surrounding rock and results in the generation of excess energy DE,which is the fundamental cause of rockburst.The ECM,which aims to offset the deep excavation effect and lower the risk of rockburst,is an active support strategy based on high pre-stress compensation.The new negative Poisson’s ratio(NPR)bolt developed has the mechanical characteristics of high strength,high toughness,and impact resistance,serving as the material basis for the ECM.The field test results reveal that the ECM and the NPR bolt succeed in controlling rockburst disasters effectively.The research results are expected to provide guidance for rockburst support in deep underground projects such as Sichuan-Xizang Railway.展开更多
Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing unde...Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing under vertical loading,the critical factors deciding the initial pretention value were found.According to these factors,a rule for the initial pretension value was put forward.The determination equations were acquired based on the principle of force equilibrium at nodes.The numerical results indicate that the internal force disequilibrium in composite bracings resulted from symmetrical load can be eliminated only in a symmetrical way,so that initial pretention values are decided only by vertical loads.The influencing coefficient leveling method,taking into account interactions between story and story,is accurate and feasible.展开更多
为了增强传统钢框筒结构(Steel framed-tubed structures,SFT)的抗震性能和震后功能可恢复能力,提出了螺栓拼接连接可更换耗能梁段-钢框筒结构(Steel framed-tubed structures with bolt-splice-connected repairable link beams,SFT-R...为了增强传统钢框筒结构(Steel framed-tubed structures,SFT)的抗震性能和震后功能可恢复能力,提出了螺栓拼接连接可更换耗能梁段-钢框筒结构(Steel framed-tubed structures with bolt-splice-connected repairable link beams,SFT-RLB)。首先给出了SFT-RLB结构构件的设计方法;然后基于OpenSEES平台提出了整体结构的弹塑性数值模型建模方法,通过子结构试验结果验证了有限元模型的准确性;继而设计了SFT和SFT-RLB结构算例,对比了2种结构的弹性和弹塑性性能;最后采用IDA方法对结构算例的抗地震倒塌能力进行评估。分析结果表明,SFT-RLB结构主要通过耗能梁段发展塑性耗散地震能量代替裙梁端部形成塑性铰,其耗能能力和变形能力均明显优于SFT结构。大震作用下,裙梁中设置的耗能梁段充分进入塑性耗散地震能量,可以有效地减小结构的基底剪力和层间侧移角,从而降低结构的地震作用,减轻主体构件的损伤程度。SFT-RLB的残余层间侧移角小于试验测得的可允许更换残余侧移角,证明结构具有震后功能可恢复潜力。算例SFT-RLB的修正倒塌储备系数ACMR远大于允许值ACMR10%(βTOT),揭示了SFT-RLB结构具有足够的抗倒塌能力储备。展开更多
基金Project(51979281)supported by the National Natural Science Foundation of ChinaProject(ZR2018MEE050)supported by the Natural Science Foundation of Shandong Province,ChinaProject(18CX02079A)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Pre-stressed bolt anchorage is the key technology for jointed rock masses in rock tunnelling,slope treatment and mining engineering.To investigate the mechanical properties and reinforcement effect of jointed rock masses with pre-stressed bolts,in this study,uniaxial compression tests were conducted on specimens with different anchoring types and flaw inclination angles.ABAQUS software was used to verify and supplement the laboratory tests.The laws of the uniaxial compressive strength(UCS)obtained from the numerical simulations and laboratory tests were consistent.The results showed that under the same flaw angle,both the UCS and elastic modulus of the bolted specimens were improved compared with those of the specimens without bolts and the improvements increased with an increase in the bolt pre-stress.Under the same anchoring type,the UCS and elastic modulus of the jointed specimens increased with an increase in the flaw angle.The pre-stressed bolt could not only restrain the slip of the specimens along the flaw surface but also change the propagation mode of the secondary cracks and limit the initiation of cracks.In addition,the plot contours of the maximum principal strain and the Tresca stress of the numerical models were influenced by the anchoring type,flaw angle,anchoring angle and bolt position.
基金supported by the National Natural Science Foundation of China (41941018)the Foundation of State Key Laboratory for Geomechanics and Deep Underground Engineering (SKLGDUEK 2217)the Foundation of Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province (PCMGH-2022-03).
文摘Rockburst disasters occur frequently during deep underground excavation,yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions.Consequently,rockburst control remains challenging in the engineering field.In this study,the mechanism of excavation-induced rockburst was briefly described,and it was proposed to apply the excavation compensation method(ECM)to rockburst control.Moreover,a field test was carried out on the Qinling Water Conveyance Tunnel.The following beneficial findings were obtained:Excavation leads to changes in the engineering stress state of surrounding rock and results in the generation of excess energy DE,which is the fundamental cause of rockburst.The ECM,which aims to offset the deep excavation effect and lower the risk of rockburst,is an active support strategy based on high pre-stress compensation.The new negative Poisson’s ratio(NPR)bolt developed has the mechanical characteristics of high strength,high toughness,and impact resistance,serving as the material basis for the ECM.The field test results reveal that the ECM and the NPR bolt succeed in controlling rockburst disasters effectively.The research results are expected to provide guidance for rockburst support in deep underground projects such as Sichuan-Xizang Railway.
基金Project of Ministry of Housing and Urban-Rural Development of China(No.2012-K2-28)
文摘Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing under vertical loading,the critical factors deciding the initial pretention value were found.According to these factors,a rule for the initial pretension value was put forward.The determination equations were acquired based on the principle of force equilibrium at nodes.The numerical results indicate that the internal force disequilibrium in composite bracings resulted from symmetrical load can be eliminated only in a symmetrical way,so that initial pretention values are decided only by vertical loads.The influencing coefficient leveling method,taking into account interactions between story and story,is accurate and feasible.
文摘为了增强传统钢框筒结构(Steel framed-tubed structures,SFT)的抗震性能和震后功能可恢复能力,提出了螺栓拼接连接可更换耗能梁段-钢框筒结构(Steel framed-tubed structures with bolt-splice-connected repairable link beams,SFT-RLB)。首先给出了SFT-RLB结构构件的设计方法;然后基于OpenSEES平台提出了整体结构的弹塑性数值模型建模方法,通过子结构试验结果验证了有限元模型的准确性;继而设计了SFT和SFT-RLB结构算例,对比了2种结构的弹性和弹塑性性能;最后采用IDA方法对结构算例的抗地震倒塌能力进行评估。分析结果表明,SFT-RLB结构主要通过耗能梁段发展塑性耗散地震能量代替裙梁端部形成塑性铰,其耗能能力和变形能力均明显优于SFT结构。大震作用下,裙梁中设置的耗能梁段充分进入塑性耗散地震能量,可以有效地减小结构的基底剪力和层间侧移角,从而降低结构的地震作用,减轻主体构件的损伤程度。SFT-RLB的残余层间侧移角小于试验测得的可允许更换残余侧移角,证明结构具有震后功能可恢复潜力。算例SFT-RLB的修正倒塌储备系数ACMR远大于允许值ACMR10%(βTOT),揭示了SFT-RLB结构具有足够的抗倒塌能力储备。
