In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter spli...In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter split Hopkinson pressure bar (SHPB) equipment with half-sine waveform loading at the strain rates ranging from 40 to 150 s- 1. With recorded signals, the energy consumption, strain rate and dynamic strength were analyzed. And the fragmentation behaviors of specimens were investigated. The experimental results show that the energy consumption density of rock increases linearly with the total incident energy. The energy consumption density is of an exponent relationship with the average size of rock fragments. The higher the energy consumption density, the more serious the fragmentation, and the better the gradation of fragments. The energy consumption density takes a good logarithm relationship with the dynamic strength of rock. The dynamic strength of rock increases with the increase of strain rate, indicating higher strain rate sensitivity.展开更多
The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method ...The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method was proposed to calculate the PEECR.The PEECR uses a simplified method to calculate the peak elastic strain energy.To solve this problem accurately,triaxial cyclic loading-unloading compression tests were carried out on shale.Strain energy parameters were calculated from the test curves.The results show that there is a linear relationship between the elastic strain energy and input strain energy,indicating that the linear energy storage law in rock is applicable to triaxial compression state.The universality of the linear energy storage law of rock under triaxial compression is also verified by the data in the published literature.Then,the peak elastic strain energy can be accurately determined using the linear energy storage law,and the PEECR is improved based on this.Finally,the PEECR and the improved PEECR were compared using the triaxial cyclic loading-unloading compression tests on three rocks(shale,red sandstone and granite),and the improved PEECR was compared with 11 existing energy-based brittleness indexes.The results show that the improved PEECR can further reflect the rock brittleness more accurately.展开更多
三峡库区发育有大量三叠系巴东组第四段紫红色泥岩(T 2 b 4,简称为巴东组紫红色泥岩),受库水位升降的影响其强度易弱化而影响库岸边坡的稳定性,开展三峡库区巴东组紫红色泥岩强度弱化特性的研究可为相关工程地质条件的评价提供参考。首...三峡库区发育有大量三叠系巴东组第四段紫红色泥岩(T 2 b 4,简称为巴东组紫红色泥岩),受库水位升降的影响其强度易弱化而影响库岸边坡的稳定性,开展三峡库区巴东组紫红色泥岩强度弱化特性的研究可为相关工程地质条件的评价提供参考。首先,依次开展了干湿循环试验和三轴压缩试验,分析巴东组紫红色泥岩的强度弱化特性,并通过CT扫描试验观察试样表面与内部的细观损伤特性;其次,基于CT扫描重构模型,开展了考虑试样内部初始损伤的三轴压缩条件下数值模拟试验;最后,基于岩石的变形特征,提出考虑岩石变开过程压密阶段的能量消耗的一种新的能量耗散模型。试验结果表明:0~10 kPa预应力下的干湿循环试验只对试样表面粗糙度有轻微的影响;干湿循环条件下,试样的峰值强度和残余强度与干湿循环次数呈负线性相关;基于CT扫描重构模型的试样三轴压缩数值模拟试验结果与室内三轴压缩试验结果具有较好的一致性,能体现试样内部的初始损伤特性,更符合实际;改进后的能量耗散模型适合于分析考虑岩石压密阶段的变形过程。展开更多
基金Projects(50674107, 10472134, 50490274) supported by the National Natural Science Foundation of China
文摘In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter split Hopkinson pressure bar (SHPB) equipment with half-sine waveform loading at the strain rates ranging from 40 to 150 s- 1. With recorded signals, the energy consumption, strain rate and dynamic strength were analyzed. And the fragmentation behaviors of specimens were investigated. The experimental results show that the energy consumption density of rock increases linearly with the total incident energy. The energy consumption density is of an exponent relationship with the average size of rock fragments. The higher the energy consumption density, the more serious the fragmentation, and the better the gradation of fragments. The energy consumption density takes a good logarithm relationship with the dynamic strength of rock. The dynamic strength of rock increases with the increase of strain rate, indicating higher strain rate sensitivity.
基金supported by the National Natural Science Foundation of China(Grant No.42077244).
文摘The peak elastic strain energy consumption ratio(PEECR)is a rock brittleness index proposed by Gong and Wang.In the present study,based on the linear energy storage law of rock under triaxial compression,a new method was proposed to calculate the PEECR.The PEECR uses a simplified method to calculate the peak elastic strain energy.To solve this problem accurately,triaxial cyclic loading-unloading compression tests were carried out on shale.Strain energy parameters were calculated from the test curves.The results show that there is a linear relationship between the elastic strain energy and input strain energy,indicating that the linear energy storage law in rock is applicable to triaxial compression state.The universality of the linear energy storage law of rock under triaxial compression is also verified by the data in the published literature.Then,the peak elastic strain energy can be accurately determined using the linear energy storage law,and the PEECR is improved based on this.Finally,the PEECR and the improved PEECR were compared using the triaxial cyclic loading-unloading compression tests on three rocks(shale,red sandstone and granite),and the improved PEECR was compared with 11 existing energy-based brittleness indexes.The results show that the improved PEECR can further reflect the rock brittleness more accurately.
文摘三峡库区发育有大量三叠系巴东组第四段紫红色泥岩(T 2 b 4,简称为巴东组紫红色泥岩),受库水位升降的影响其强度易弱化而影响库岸边坡的稳定性,开展三峡库区巴东组紫红色泥岩强度弱化特性的研究可为相关工程地质条件的评价提供参考。首先,依次开展了干湿循环试验和三轴压缩试验,分析巴东组紫红色泥岩的强度弱化特性,并通过CT扫描试验观察试样表面与内部的细观损伤特性;其次,基于CT扫描重构模型,开展了考虑试样内部初始损伤的三轴压缩条件下数值模拟试验;最后,基于岩石的变形特征,提出考虑岩石变开过程压密阶段的能量消耗的一种新的能量耗散模型。试验结果表明:0~10 kPa预应力下的干湿循环试验只对试样表面粗糙度有轻微的影响;干湿循环条件下,试样的峰值强度和残余强度与干湿循环次数呈负线性相关;基于CT扫描重构模型的试样三轴压缩数值模拟试验结果与室内三轴压缩试验结果具有较好的一致性,能体现试样内部的初始损伤特性,更符合实际;改进后的能量耗散模型适合于分析考虑岩石压密阶段的变形过程。
