In order to investigate the failure process of brittle rock under triaxial compression through both experimental and numerical approaches, the particle simulation method was used in numerical simulations and the simul...In order to investigate the failure process of brittle rock under triaxial compression through both experimental and numerical approaches, the particle simulation method was used in numerical simulations and the simulated results were compared with those of the experiment. The numerical simulation results, such as fracture propagation, microcrack distribution, stress-strain response, and damage patterns, were discussed in detail. The simulated results under various confining pressures （0-60 MPa） are in good agreement with the experimental results. The simulated results reveal that rock failure is caused by axial splitting under uniaxial compression. As the confining pressure increases, rock failure occurs in a few localized shear planes and the rock mechanical behavior is changed from brittle to ductile. Consequently, the peak failure strength, microcrack numbers, and the shear plane angle increase, but the ratio of tensile to shear microcracks decreases. The damage formation during the compression simulations indicates that the particle simulation method can produce similar behaviors as those observed through laboratory compression tests.展开更多
针对新疆某油田超深井在更换密封件提起采油四通时,发现井口悬挂器卡瓦夹持处套管断裂的问题,结合现场X1井使用的ø232.5 mm W型卡瓦悬挂器结构,建立了悬挂器坐挂-卡瓦夹持套管的三维有限元模型。根据第四强度理论推导出卡瓦效应的...针对新疆某油田超深井在更换密封件提起采油四通时,发现井口悬挂器卡瓦夹持处套管断裂的问题,结合现场X1井使用的ø232.5 mm W型卡瓦悬挂器结构,建立了悬挂器坐挂-卡瓦夹持套管的三维有限元模型。根据第四强度理论推导出卡瓦效应的套管极限载荷计算公式,并通过有限元计算得到了理论公式的修正系数为0.913,同时得到在套管坐挂时,X1井卡瓦效应的套管极限载荷为6400 kN。有限元计算结果表明:卡瓦部分套管上的应力呈现非均匀分布,尤其是套管外壁非均匀程度较严重,且外壁牙痕上的应力集中是套管损伤、裂纹起裂和断裂的主要原因;如果存在较高的环空压力,在卡瓦部分或过渡区套管均有可能发生断裂失效破坏。建议选择无齿痕的卡瓦夹持套管,或者采用全金属密封的心轴式悬挂器,避免卡瓦悬挂器造成套管损伤破坏。研究方法和成果可为深井超深井卡瓦悬挂器套管的安全评价提供理论指导。展开更多
With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been ...With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been paid little attention to in past research.In this paper,the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out.The mechanical fracture properties of this material were studied,and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness.Through the tests,the fracture behavior of materials with wide stress triaxiality was obtained,and each specimen’s fracture locations and fracture strains were determined.Parameters of a generalized incremental stress state dependent damage model(GISSMO)of the material were calibrated,and the model’s accuracy was verified with test results from a 45°shear specimen.The GISSMO failure model accurately reflected the fracture characteristics of the material.The mesh dependency of this model was modified and discussed.The results show that the simulation agrees well with experimental data for the force-displacement curve after correction,but the strain distribution needs to be further studied and improved.展开更多
基金supported by the Graduate Degree Thesis Innovation Foundation of Central South University (No.2009ssxt226)
文摘In order to investigate the failure process of brittle rock under triaxial compression through both experimental and numerical approaches, the particle simulation method was used in numerical simulations and the simulated results were compared with those of the experiment. The numerical simulation results, such as fracture propagation, microcrack distribution, stress-strain response, and damage patterns, were discussed in detail. The simulated results under various confining pressures （0-60 MPa） are in good agreement with the experimental results. The simulated results reveal that rock failure is caused by axial splitting under uniaxial compression. As the confining pressure increases, rock failure occurs in a few localized shear planes and the rock mechanical behavior is changed from brittle to ductile. Consequently, the peak failure strength, microcrack numbers, and the shear plane angle increase, but the ratio of tensile to shear microcracks decreases. The damage formation during the compression simulations indicates that the particle simulation method can produce similar behaviors as those observed through laboratory compression tests.
文摘针对新疆某油田超深井在更换密封件提起采油四通时,发现井口悬挂器卡瓦夹持处套管断裂的问题,结合现场X1井使用的ø232.5 mm W型卡瓦悬挂器结构,建立了悬挂器坐挂-卡瓦夹持套管的三维有限元模型。根据第四强度理论推导出卡瓦效应的套管极限载荷计算公式,并通过有限元计算得到了理论公式的修正系数为0.913,同时得到在套管坐挂时,X1井卡瓦效应的套管极限载荷为6400 kN。有限元计算结果表明:卡瓦部分套管上的应力呈现非均匀分布,尤其是套管外壁非均匀程度较严重,且外壁牙痕上的应力集中是套管损伤、裂纹起裂和断裂的主要原因;如果存在较高的环空压力,在卡瓦部分或过渡区套管均有可能发生断裂失效破坏。建议选择无齿痕的卡瓦夹持套管,或者采用全金属密封的心轴式悬挂器,避免卡瓦悬挂器造成套管损伤破坏。研究方法和成果可为深井超深井卡瓦悬挂器套管的安全评价提供理论指导。
基金National Natural Scienceof China(Grant No.52172409)Sichuan Provincial Outstanding Youth Fund of China(Grant No.2022JDJQ0025)。
文摘With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been paid little attention to in past research.In this paper,the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out.The mechanical fracture properties of this material were studied,and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness.Through the tests,the fracture behavior of materials with wide stress triaxiality was obtained,and each specimen’s fracture locations and fracture strains were determined.Parameters of a generalized incremental stress state dependent damage model(GISSMO)of the material were calibrated,and the model’s accuracy was verified with test results from a 45°shear specimen.The GISSMO failure model accurately reflected the fracture characteristics of the material.The mesh dependency of this model was modified and discussed.The results show that the simulation agrees well with experimental data for the force-displacement curve after correction,but the strain distribution needs to be further studied and improved.
