The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of mu...The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of muds tone, sands tone and limestone specimens during complete stress-strain process and their mechanic property were investigated. A new type of device for the observation of surrounding rock stability-borehole ultrasonic device with completely dry coupling was developed to get better coupling and more accurate measurement data comparing with those of water coupling situation. Preliminary study on the application of ultrasonic measurement technique at belt conveyor roadway of north wing in Baodian Coal Mine (Shandong province) was conducted. Based on the interrelations between the complete stress-strain properties of specimens and their wave properties, the structural properties of surrounding rocks, the range of yield zones, and the change of stresses within surrounding rocks when a longwall face was across over the roadway were analyzed.Therefore,a new and feasible way was found for the research on the deformation law of surrounding rock of roadway and rational selection of support parameters.展开更多
Based on Hamilton principle,the governing differential equations and the corresponding boundary conditions of steel-concrete composite box girder with consideration of the shear lag effect meeting self equilibrated st...Based on Hamilton principle,the governing differential equations and the corresponding boundary conditions of steel-concrete composite box girder with consideration of the shear lag effect meeting self equilibrated stress,shear deformation,slip,as well as rotational inertia were induced.Therefore,natural frequency equations were obtained for the boundary types,such as simple support,cantilever,continuous girder and fixed support at two ends.The ANSYS finite element solutions were compared with the analytical solutions by calculation examples and the validity of the proposed approach was verified,which also shows the correctness of longitudinal warping displacement functions.Some meaningful conclusions for engineering design were obtained.The decrease extent of each order natural frequency of the steel-concrete composite box-girder is great under action of the shear lag effect.The shear-lag effect of steel-concrete composite box girder increases when frequency order rises,and increases while span-width ratio decreases.The proposed approach provides theoretical basis for further research of free vibration characteristics of steel-concrete composite box-girder.展开更多
To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge blo...To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics展开更多
An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For thi...An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.展开更多
Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage ...Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage theory. It has been demonstrated that how the influence of confining pressure on the deformation behavior and AE characteristics in rocks can be inferred from a simple mechanics model. The results show that loading confining pressure sharply brings out increasing of AE. On the other hand, few AE emits when confining pressure is loaded sharply, and AE occurs again when axial pressure keeps on increasing. These results have been well simulated with computer and show close correspondence with directly measured curves in experiments.展开更多
The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine t...The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated using a two-dimensional finite element model that was developed in ANSYS14.5 Software. Also, two-dimensional finite element stress analysis was developed to determine the stress distribution needed to evaluate the failure. Tsai-Wu failure criterion was used in the analysis with the characteristic curve to predict bearing strength. The results of the analysis showed good agreement with experimental data.展开更多
By using numerical analysis methods to simulate the deep excavation,a lot of analyses are established on the basis of two-dimensional plane strain,ignoring the fact that foundation pit possesses three dimensions. For ...By using numerical analysis methods to simulate the deep excavation,a lot of analyses are established on the basis of two-dimensional plane strain,ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation,people always take linear and nonlinear model,without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics,the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.展开更多
Based on the study about the geological background of Beiya Gold Deposit, numerical simulation was conducted about the three-dimensional structural stress field for Beiya Gold Deposit by applying finite element theory...Based on the study about the geological background of Beiya Gold Deposit, numerical simulation was conducted about the three-dimensional structural stress field for Beiya Gold Deposit by applying finite element theory and by employing a linear elasticity model. Results of the simulation indicate that the Beiya syncline is a faulted basin, and a hidden fracture occurs in the west wing of the syncline.Under the action of the EW-trending compressive force, four nearly NS-trending fractures (groups) were generated in the stress stretching areas of the two wings of the syncline, and these fractures constitute favorable tectonic positions for the upward intrusion of porphyry magma and the occurrence of Au-Pb-Zn polymetallic deposits.展开更多
基金This project is supported by returned specialists fund of China National Coal Corporation
文摘The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of muds tone, sands tone and limestone specimens during complete stress-strain process and their mechanic property were investigated. A new type of device for the observation of surrounding rock stability-borehole ultrasonic device with completely dry coupling was developed to get better coupling and more accurate measurement data comparing with those of water coupling situation. Preliminary study on the application of ultrasonic measurement technique at belt conveyor roadway of north wing in Baodian Coal Mine (Shandong province) was conducted. Based on the interrelations between the complete stress-strain properties of specimens and their wave properties, the structural properties of surrounding rocks, the range of yield zones, and the change of stresses within surrounding rocks when a longwall face was across over the roadway were analyzed.Therefore,a new and feasible way was found for the research on the deformation law of surrounding rock of roadway and rational selection of support parameters.
基金Projects(51078355,50938008)supported by the National Natural Science Foundation of ChinaProject(094801020)supported by the Academic Scholarship for Doctoral Candidates of the Ministry of Education,China+1 种基金Project(CX2011B093)supported by the Doctoral Candidate Research Innovation Project of Hunan Province,ChinaProject(20117Q008)supported by the Central University Basic Scientific Research Business Expenses Special Fund of China
文摘Based on Hamilton principle,the governing differential equations and the corresponding boundary conditions of steel-concrete composite box girder with consideration of the shear lag effect meeting self equilibrated stress,shear deformation,slip,as well as rotational inertia were induced.Therefore,natural frequency equations were obtained for the boundary types,such as simple support,cantilever,continuous girder and fixed support at two ends.The ANSYS finite element solutions were compared with the analytical solutions by calculation examples and the validity of the proposed approach was verified,which also shows the correctness of longitudinal warping displacement functions.Some meaningful conclusions for engineering design were obtained.The decrease extent of each order natural frequency of the steel-concrete composite box-girder is great under action of the shear lag effect.The shear-lag effect of steel-concrete composite box girder increases when frequency order rises,and increases while span-width ratio decreases.The proposed approach provides theoretical basis for further research of free vibration characteristics of steel-concrete composite box-girder.
基金Supported by the National Natural Science Foundation of China(50874085)
文摘To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics
基金the support of the National Natural Science Foundation of China (Grant No. 51309179)the National High Technology Research and Development Program of China (863 Program, Grant No. 2012AA051705)+2 种基金the International S&T Cooperation Program of China (Grant No. 2012DFA70490)the State Key Laboratory of Hydraulic Engineering Simulation and Safety (Tianjin University)the Tianjin Municipal Natural Science Foundation (Grant Nos. 14JCQNJC07000 and 13JCYBJC19100)
文摘An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.
文摘Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage theory. It has been demonstrated that how the influence of confining pressure on the deformation behavior and AE characteristics in rocks can be inferred from a simple mechanics model. The results show that loading confining pressure sharply brings out increasing of AE. On the other hand, few AE emits when confining pressure is loaded sharply, and AE occurs again when axial pressure keeps on increasing. These results have been well simulated with computer and show close correspondence with directly measured curves in experiments.
文摘The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated using a two-dimensional finite element model that was developed in ANSYS14.5 Software. Also, two-dimensional finite element stress analysis was developed to determine the stress distribution needed to evaluate the failure. Tsai-Wu failure criterion was used in the analysis with the characteristic curve to predict bearing strength. The results of the analysis showed good agreement with experimental data.
文摘By using numerical analysis methods to simulate the deep excavation,a lot of analyses are established on the basis of two-dimensional plane strain,ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation,people always take linear and nonlinear model,without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics,the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.
文摘Based on the study about the geological background of Beiya Gold Deposit, numerical simulation was conducted about the three-dimensional structural stress field for Beiya Gold Deposit by applying finite element theory and by employing a linear elasticity model. Results of the simulation indicate that the Beiya syncline is a faulted basin, and a hidden fracture occurs in the west wing of the syncline.Under the action of the EW-trending compressive force, four nearly NS-trending fractures (groups) were generated in the stress stretching areas of the two wings of the syncline, and these fractures constitute favorable tectonic positions for the upward intrusion of porphyry magma and the occurrence of Au-Pb-Zn polymetallic deposits.
