动态荷载下岩石裂纹的扩张机理研究
发布时间：2018-07-23 21:00
【摘要】：动态荷载下岩石裂隙的破坏问题是关系到岩土工程建设和风险评估等各个方面的重大课题。实际岩土建设工程中所遇到的岩石裂隙的扩展破坏问题多是由于动态荷载的作用造成,如地震荷载、爆破荷载等等。在岩石断裂力学方面,静态荷载和冲击荷载都有了一定程度的研究。然而对于起衔接作用的低速荷载下岩石裂隙的扩展机理还研究尚少。因此本文将通过嵌入两大破坏准则的离散有限元程序(EDEM)对不同速度荷载下岩石裂隙的破坏进行数值模拟计算,并对其破坏的形态差异和力学特性差异进行对比分析,从而得出不同加载速度对岩石裂隙破坏的影响。对不同加载速度对岩石裂隙扩展的研究可以更进一步理解为在不同的应变率下裂隙扩展的机理,为全面系统地研究岩石裂隙在各种动态荷载下的扩展特性奠定基础。同时,可以对工程实践中的重要岩土工程选址和建筑工程风险评估等有着一定的指导依据。本文中利用扩展离散元程序,通过对多种加载速度和不同预制裂隙角度的模型的模拟,对其结果进行整理分析,发现加载速度对岩石裂隙扩展产状和岩体力学特性两方面的影响。总结出了在增大加载速度后模型裂隙扩展产状与静载作用下的相似性和差异性。在扩展产状方面,高速加载下模型的裂隙扩展将会出现更多的次生裂隙,甚至形成破坏带,最后达到与冲击破坏相似的“X”形破坏产状；在模型力学特性方面,通过统计分析每次计算中加载板的应力、位移等数据,发现在高速加载下模型在破坏前将会达到更大的应力值。同时对在动态荷载下的模型的力学响应做出了分析,发现了应力波在岩体中传播的研究在动力学研究以及实际岩土工程中的重要性。动态荷载下岩石的裂隙扩展和动态断裂力学将是解决岩土工程中动态荷载对地层和建筑工程影响的重要理论基础。在今后的研究中,通过对不同加载速度下岩石裂隙力学反应和破坏产状的深入探讨可以全面地研究岩石的动态断裂力学,以求能达到精确地对动态荷载下岩石裂隙的风险评估和扩展预测等对实际工程有指导意义的目的。
[Abstract]:The failure of rock fissures under dynamic load is an important subject related to geotechnical engineering construction and risk assessment. In the actual geotechnical construction engineering, the problems of rock crack expansion and failure are mostly caused by dynamic loads, such as earthquake load, blasting load, and so on. In rock fracture mechanics, static load and impact load have been studied to some extent. However, there is little research on the mechanism of rock fracture propagation under low speed load. In this paper, the failure of rock fractures under different velocity loads is simulated by the discrete finite element program (EDEM), which embed two failure criteria, and the difference of fracture morphology and mechanical properties is compared and analyzed. The influence of different loading speed on rock fracture failure is obtained. The study of crack propagation at different loading speeds can be further understood as the mechanism of crack propagation at different strain rates, which lays a foundation for a comprehensive and systematic study of the propagation characteristics of rock fractures under various dynamic loads. At the same time, it can provide some guidance for geotechnical engineering site selection and construction engineering risk assessment in engineering practice. In this paper, the extended discrete element program is used to simulate the models with different loading speeds and different prefabricated fracture angles, and the results are analyzed. The effect of loading speed on the occurrence of crack propagation and mechanical properties of rock mass is found. The similarity and difference between the occurrence of crack propagation and the static load in the model are summarized after increasing the loading speed. In the aspect of propagation occurrence, the crack propagation of the model under high-speed loading will appear more secondary cracks, even form failure zone, and finally achieve the "X" shape failure occurrence similar to the impact failure, and in the mechanical properties of the model, Through the statistical analysis of the stress and displacement data of the loaded plate in each calculation, it is found that the model will reach greater stress value before failure under high-speed loading. At the same time, the mechanical response of the model under dynamic load is analyzed, and the importance of the study of stress wave propagation in rock mass is found in the study of dynamics as well as in the actual geotechnical engineering. Crack propagation and dynamic fracture mechanics of rock under dynamic load will be the important theoretical basis to solve the influence of dynamic load on stratum and building engineering in geotechnical engineering. In the future research, the dynamic fracture mechanics of rock can be studied comprehensively through the deep discussion on the mechanical reaction and failure state of rock fracture under different loading speeds. In order to achieve accurate risk assessment and expansion prediction of rock fractures under dynamic load, it is of guiding significance to practical engineering.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45
本文编号：2140621
[Abstract]:The failure of rock fissures under dynamic load is an important subject related to geotechnical engineering construction and risk assessment. In the actual geotechnical construction engineering, the problems of rock crack expansion and failure are mostly caused by dynamic loads, such as earthquake load, blasting load, and so on. In rock fracture mechanics, static load and impact load have been studied to some extent. However, there is little research on the mechanism of rock fracture propagation under low speed load. In this paper, the failure of rock fractures under different velocity loads is simulated by the discrete finite element program (EDEM), which embed two failure criteria, and the difference of fracture morphology and mechanical properties is compared and analyzed. The influence of different loading speed on rock fracture failure is obtained. The study of crack propagation at different loading speeds can be further understood as the mechanism of crack propagation at different strain rates, which lays a foundation for a comprehensive and systematic study of the propagation characteristics of rock fractures under various dynamic loads. At the same time, it can provide some guidance for geotechnical engineering site selection and construction engineering risk assessment in engineering practice. In this paper, the extended discrete element program is used to simulate the models with different loading speeds and different prefabricated fracture angles, and the results are analyzed. The effect of loading speed on the occurrence of crack propagation and mechanical properties of rock mass is found. The similarity and difference between the occurrence of crack propagation and the static load in the model are summarized after increasing the loading speed. In the aspect of propagation occurrence, the crack propagation of the model under high-speed loading will appear more secondary cracks, even form failure zone, and finally achieve the "X" shape failure occurrence similar to the impact failure, and in the mechanical properties of the model, Through the statistical analysis of the stress and displacement data of the loaded plate in each calculation, it is found that the model will reach greater stress value before failure under high-speed loading. At the same time, the mechanical response of the model under dynamic load is analyzed, and the importance of the study of stress wave propagation in rock mass is found in the study of dynamics as well as in the actual geotechnical engineering. Crack propagation and dynamic fracture mechanics of rock under dynamic load will be the important theoretical basis to solve the influence of dynamic load on stratum and building engineering in geotechnical engineering. In the future research, the dynamic fracture mechanics of rock can be studied comprehensively through the deep discussion on the mechanical reaction and failure state of rock fracture under different loading speeds. In order to achieve accurate risk assessment and expansion prediction of rock fractures under dynamic load, it is of guiding significance to practical engineering.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45
【参考文献】
相关期刊论文 前1条
1 胡柳青;李夕兵;龚声武;;冲击载荷作用下裂纹动态响应的数值模拟[J];爆炸与冲击;2006年03期
，本文编号：2140621
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