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A platform for research: civil engineering, architecture and urbanism
Blockiness level of rock mass around underground powerhouse of Three Gorges Project
Graphical abstract Display Omitted
Highlights We present the new concept of blockiness. Thirty-five theoretical rocks are established by considering fracture classifications. We investigated the blockiness of the theoretical rocks and an actual fractured rock. Blockiness results of the actual fractured rock and the theoretical rocks are in good agreement.
Abstract A fundamental question in rock mechanics is whether a rock mass is a continuum or an assemblage of isolated blocks. Some models have treated rock masses as continuums and others, as isolated blocks. Most rock masses are neither continuums nor isolated blocks, but something between them. This study presents a new concept of blockiness to measure a rock’s level of being an assemblage of isolated blocks. Thirty-five types of theoretical fractured rock mass structural models are established by considering fracture classifications. For each structure, rock blocks are identified using the GeneralBlock program, and the blockiness is investigated. The blockiness of the surrounding rock mass of the underground powerhouse in the Three Gorges Project is systematically investigated. Based on measurements of fractures obtained from a field survey, a discrete fracture network model is established by an inverse method for identifying and analyzing rock blocks. The results show that the blockiness of the surrounding rock mass of the underground powerhouse is only 4‰; the total rock mass shows very good quality and stability; the number of blocks in the rock mass is quite small; therefore, the volume of isolated blocks only accounts for a very small proportion of the total rock volume; and the rock mass can be considered a continuum. The excavation process of the underground powerhouse in the Three Gorges Project verified these conclusions; only a few blocks are formed by fractures in the rock mass of the underground powerhouse. The calculation results for the 35models show that the blockiness of the rock mass having medium persistence and very wide spacing is very low. The structure of the rock mass around the underground powerhouse is of this type. Its blockiness agrees with the model calculation results. Therefore, the calculation results for the 35 models are useful in predicting the stability of rock masses having different persistence and spacing, and they could serve as a reference for quantifying the quality of rock masses in other projects. And, in this study, the concept of the blockiness level of rock mass was determined by one example only, and more studies would be concluded for other projects to validate this concept in future study.
Blockiness level of rock mass around underground powerhouse of Three Gorges Project
Graphical abstract Display Omitted
Highlights We present the new concept of blockiness. Thirty-five theoretical rocks are established by considering fracture classifications. We investigated the blockiness of the theoretical rocks and an actual fractured rock. Blockiness results of the actual fractured rock and the theoretical rocks are in good agreement.
Abstract A fundamental question in rock mechanics is whether a rock mass is a continuum or an assemblage of isolated blocks. Some models have treated rock masses as continuums and others, as isolated blocks. Most rock masses are neither continuums nor isolated blocks, but something between them. This study presents a new concept of blockiness to measure a rock’s level of being an assemblage of isolated blocks. Thirty-five types of theoretical fractured rock mass structural models are established by considering fracture classifications. For each structure, rock blocks are identified using the GeneralBlock program, and the blockiness is investigated. The blockiness of the surrounding rock mass of the underground powerhouse in the Three Gorges Project is systematically investigated. Based on measurements of fractures obtained from a field survey, a discrete fracture network model is established by an inverse method for identifying and analyzing rock blocks. The results show that the blockiness of the surrounding rock mass of the underground powerhouse is only 4‰; the total rock mass shows very good quality and stability; the number of blocks in the rock mass is quite small; therefore, the volume of isolated blocks only accounts for a very small proportion of the total rock volume; and the rock mass can be considered a continuum. The excavation process of the underground powerhouse in the Three Gorges Project verified these conclusions; only a few blocks are formed by fractures in the rock mass of the underground powerhouse. The calculation results for the 35models show that the blockiness of the rock mass having medium persistence and very wide spacing is very low. The structure of the rock mass around the underground powerhouse is of this type. Its blockiness agrees with the model calculation results. Therefore, the calculation results for the 35 models are useful in predicting the stability of rock masses having different persistence and spacing, and they could serve as a reference for quantifying the quality of rock masses in other projects. And, in this study, the concept of the blockiness level of rock mass was determined by one example only, and more studies would be concluded for other projects to validate this concept in future study.
Blockiness level of rock mass around underground powerhouse of Three Gorges Project
Xia, Lu (author) / Li, Maohua (author) / Chen, Youhua (author) / Zheng, Yinhe (author) / Yu, Qingchun (author)
Tunnelling and Underground Space Technology ; 48 ; 67-76
2015-02-16
10 pages
Article (Journal)
Electronic Resource
English
Blockiness level of rock mass around underground powerhouse of Three Gorges Project
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