A series of triaxial laboratory experiments are performed on thick-walled hollow cylindrical samples of boom clay.The aim of this testing program is to better understand the anisotropic deformation during the excavati...A series of triaxial laboratory experiments are performed on thick-walled hollow cylindrical samples of boom clay.The aim of this testing program is to better understand the anisotropic deformation during the excavation.The testing conditions are similar to those to be experienced by host rocks around disposal galleries for radioactive waste.X-ray computed tomography is performed at different steps for each test with the samples remaining inside the loading cell.Initial analysis of the tomography images allows of the observation of the deformation of the central hole.In addition,particles manual tracking and 3D volumetric digital image correlation processing methods are considered being used to analyze the particles displacements and the boundary deformation of the sample quantitatively.An unsymmetrical damaged zone is induced around the hole,with a reverse deformation trend being found at the boundary after unloading,which indicates that the significant anisotropic deformation of boom clay can be induced by mechanical unloading.展开更多
In order to study the failure of surrounding rock under high in situ stress in deep underground engineering projects, disturbed by excavation unloading, we carried out triaxial unloading experiments using thickwalled ...In order to study the failure of surrounding rock under high in situ stress in deep underground engineering projects, disturbed by excavation unloading, we carried out triaxial unloading experiments using thickwalled cylinder specimens on a TATW-2000 rock servo-controlled triaxial testing machine in a laboratory. The specimens were made of limestone material, taken from Tongshan county, Xuzhou city, Jiangsu province, China. In our experiments, rock deformation and failure behavior was studied through loading and unloading of inner hole pressure of thick-walled cylinder specimens. At first, the axial stress, confining pressure and inner pressure were increased simultaneously to a specified designed state of stress. Then, keeping the axial stress and confining pressure stable, the pressure on the inner hole was decreased until the specimen was fractured. When the inner pressure was released completely but the specimen did not fracture, the confining pressure was decreased subsequently until complete failure occurred. Our experimental results suggest that traces of major circular ringlike fractures with a number of radial cracks often appear in thick cylinder walls. This type of ringlike failure phenomenon, similar to intermittent zonal fracturing characteristics of deep exploitation, has, so far, not been published. Our experimental results show that rock deformation and failure behavior of thick-walled limestone cylinders vary under different stress paths between loading and unloading. Tensile failure and orderly failure surfaces occur under unloading conditions while irregular damaged rock blocks are produced during loading failure. This type of triaxial unloading experiment provides for new research methodology and approach for thorough investigations on intermittent zonal fracturing in deep underground excavations.展开更多
Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)th...Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)thermodynamic code,this paper introduced the universal solid equation of state(EOS)VINET.In order to truly reflect the compressibility of nanocarbon under the extremely high-temperature and high-pressure environment in detonation,an SVM(support vector machine)was utilized to optimize the input parameters of carbon.The detonation performance of several explosives with different densities was calculated by the optimized universal EOS,and the results show that the thermodynamic code coupled with the universal solid EOS VINET can predict the detonation performance parameters of explosives well.To investigate the application of the thermodynamic code with the improved VINET EOS in the working capacity of explosives,the interrelationship between pressure P-particle velocity u and pressure P-volume V were computed for the detonation products of TNT and HMX-based PBX(HMX:binder:insensitive agent=95:4.3:0.7)in the CJ isentropic state.A universal curve proposed by Cooper was used to compared the computed isentropic state,where the ratio of pressure to CJ state were plotted against the ratio of velocity to CJ state.The parameters of the JWL(Jones-Wilkins-Lee)EOS for detonation products were obtained by fitting the P-V curve.The cylinder tests of TNT and HMX-based PBX were numerically simulated using the LS-DYNA,it is verified that,within a certain range,the improved algorithm has superiority in describing the working capacity of explosives.展开更多
基金supported by Fundamental Research Funds for the Central Universities (No.FRF-TP-14-033A1)TIMODAZ project as part of the sixth EURATOM framework programme for nuclear research and training activities (2002–2006)The Department of Diagnostic and Interventional Radiology of the CHUV and the collaboration with Laboratoire 3S-R,Grenoble are gratefully acknowledged
文摘A series of triaxial laboratory experiments are performed on thick-walled hollow cylindrical samples of boom clay.The aim of this testing program is to better understand the anisotropic deformation during the excavation.The testing conditions are similar to those to be experienced by host rocks around disposal galleries for radioactive waste.X-ray computed tomography is performed at different steps for each test with the samples remaining inside the loading cell.Initial analysis of the tomography images allows of the observation of the deformation of the central hole.In addition,particles manual tracking and 3D volumetric digital image correlation processing methods are considered being used to analyze the particles displacements and the boundary deformation of the sample quantitatively.An unsymmetrical damaged zone is induced around the hole,with a reverse deformation trend being found at the boundary after unloading,which indicates that the significant anisotropic deformation of boom clay can be induced by mechanical unloading.
基金supported by the National Natural Science Foundation of China (Nos.50804046, 50490273 and 50774082)the Scientific Research Fund for Youths of CUMT (No. 0B080240)
文摘In order to study the failure of surrounding rock under high in situ stress in deep underground engineering projects, disturbed by excavation unloading, we carried out triaxial unloading experiments using thickwalled cylinder specimens on a TATW-2000 rock servo-controlled triaxial testing machine in a laboratory. The specimens were made of limestone material, taken from Tongshan county, Xuzhou city, Jiangsu province, China. In our experiments, rock deformation and failure behavior was studied through loading and unloading of inner hole pressure of thick-walled cylinder specimens. At first, the axial stress, confining pressure and inner pressure were increased simultaneously to a specified designed state of stress. Then, keeping the axial stress and confining pressure stable, the pressure on the inner hole was decreased until the specimen was fractured. When the inner pressure was released completely but the specimen did not fracture, the confining pressure was decreased subsequently until complete failure occurred. Our experimental results suggest that traces of major circular ringlike fractures with a number of radial cracks often appear in thick cylinder walls. This type of ringlike failure phenomenon, similar to intermittent zonal fracturing characteristics of deep exploitation, has, so far, not been published. Our experimental results show that rock deformation and failure behavior of thick-walled limestone cylinders vary under different stress paths between loading and unloading. Tensile failure and orderly failure surfaces occur under unloading conditions while irregular damaged rock blocks are produced during loading failure. This type of triaxial unloading experiment provides for new research methodology and approach for thorough investigations on intermittent zonal fracturing in deep underground excavations.
基金the financial support from the National Natural Science Foundation of China(No.11902298)the National Key Research and Development Program of China(No.2017YFC0804701)。
文摘Thermodynamic calculation is the theoretical basis for the study of initiation and detonation,as well as the prerequisite for forecasting the detonation performance of unknown explosives.Based on the VLWR(Virial-Wu)thermodynamic code,this paper introduced the universal solid equation of state(EOS)VINET.In order to truly reflect the compressibility of nanocarbon under the extremely high-temperature and high-pressure environment in detonation,an SVM(support vector machine)was utilized to optimize the input parameters of carbon.The detonation performance of several explosives with different densities was calculated by the optimized universal EOS,and the results show that the thermodynamic code coupled with the universal solid EOS VINET can predict the detonation performance parameters of explosives well.To investigate the application of the thermodynamic code with the improved VINET EOS in the working capacity of explosives,the interrelationship between pressure P-particle velocity u and pressure P-volume V were computed for the detonation products of TNT and HMX-based PBX(HMX:binder:insensitive agent=95:4.3:0.7)in the CJ isentropic state.A universal curve proposed by Cooper was used to compared the computed isentropic state,where the ratio of pressure to CJ state were plotted against the ratio of velocity to CJ state.The parameters of the JWL(Jones-Wilkins-Lee)EOS for detonation products were obtained by fitting the P-V curve.The cylinder tests of TNT and HMX-based PBX were numerically simulated using the LS-DYNA,it is verified that,within a certain range,the improved algorithm has superiority in describing the working capacity of explosives.
