Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insid...Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.展开更多
The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair ...The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair rates to be constant.The system availability is defined as the ability of the system to satisfy consumer demand.Factor improvement method and standby redundancy method are used to improve the system design.To evaluate availability of the both original and improved systems,a fast technique,based on universal generating function,is adopted.The availability equivalence factor is introduced to compare different system designs.Two types of availability equivalence factors of the system are derived.A numerical example is provided to illustrate how to utilize the obtained results.展开更多
基金funded by the Major Basic Research and Development Program of China(No.2014CB046905)the Ph.D.Programs Foundation of Ministry of Education of China(No.20130095110018)
文摘Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.
基金supported in part by the Natural Science Foundation of Hebei Province under Grant Nos.A2014203096 and G2012203136the National Natural Science Foundation of China under Grant No.11201408the Science Research Project of Yanshan University under Grant No.13LGA017
文摘The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair rates to be constant.The system availability is defined as the ability of the system to satisfy consumer demand.Factor improvement method and standby redundancy method are used to improve the system design.To evaluate availability of the both original and improved systems,a fast technique,based on universal generating function,is adopted.The availability equivalence factor is introduced to compare different system designs.Two types of availability equivalence factors of the system are derived.A numerical example is provided to illustrate how to utilize the obtained results.
