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
研究了两跳缓存辅助(Buffer-aided)多中继索引调制OFDM(Orthogonal Frequency Division Multiplexing with Index Modulation,OFDM-IM)的中断性能,并提出了一种名为“最大可用缓存/最大接收信噪比之和(Max Available Buffer/Max Sum of ...研究了两跳缓存辅助(Buffer-aided)多中继索引调制OFDM(Orthogonal Frequency Division Multiplexing with Index Modulation,OFDM-IM)的中断性能,并提出了一种名为“最大可用缓存/最大接收信噪比之和(Max Available Buffer/Max Sum of Received Signal-to-Noise Ratio,MAB/MSR)”的中继/子载波组联合选择方案。采用译码转发(Decode and Forward,DF)中继协议,运用马尔科夫链(Markov Chain,MC)理论分析了中继的缓存空间状态变化情况,推导了MAB/MSR方案可达中断概率的闭式解,理论分析与蒙特卡罗仿真数值吻合良好。结果表明,MAB/MSR方案获得了比缓存辅助最大链路选择(Max Link Selection,MLS)、最大权重中继选择(Max Weight Relay Selection,MWRS)方案更好的系统中断性能。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.
文摘研究了两跳缓存辅助(Buffer-aided)多中继索引调制OFDM(Orthogonal Frequency Division Multiplexing with Index Modulation,OFDM-IM)的中断性能,并提出了一种名为“最大可用缓存/最大接收信噪比之和(Max Available Buffer/Max Sum of Received Signal-to-Noise Ratio,MAB/MSR)”的中继/子载波组联合选择方案。采用译码转发(Decode and Forward,DF)中继协议,运用马尔科夫链(Markov Chain,MC)理论分析了中继的缓存空间状态变化情况,推导了MAB/MSR方案可达中断概率的闭式解,理论分析与蒙特卡罗仿真数值吻合良好。结果表明,MAB/MSR方案获得了比缓存辅助最大链路选择(Max Link Selection,MLS)、最大权重中继选择(Max Weight Relay Selection,MWRS)方案更好的系统中断性能。
