Jinping traffic tunnel is one of the deepest traffic tunnels in the world with a maximum overburden of 2 375 m and the overburden over 73% of its total length is larger than 1 500 m. The tunnel is 17.5 km long and des...Jinping traffic tunnel is one of the deepest traffic tunnels in the world with a maximum overburden of 2 375 m and the overburden over 73% of its total length is larger than 1 500 m. The tunnel is 17.5 km long and designed to provide a shortcut road between two hydropower stations： Jinping I and Jinping II of the Jinping Hydropower Project, located on Yalong River, Liangshan State, Sichuan Province, China. The tunnel is so deep that building any shafts is impossible. The construction starts from both ends （east and west ends）, and the construction length from the west end is 10 km with a blind heading. This paper deals with an overview of this project and analysis of the engineering features, as well as key technologies developed and applied during the construction, including geological prediction, rock burst prevention under a super high in-situ stress, sealing of groundwater with a high pressure and big flow rate, ventilation for a blind heading of 10 km, wet spraying of shotcrete at zones of rock burst and rich water, etc. The application of the new technologies to the construction achieved a high quality tunnel within the contract period.展开更多
A recent seismic event was recorded by a deep longwall mine in Virginia at 3.7 ML on the local magnitude scale and 3.4 MMS by the United States Geological Survey(USGS) in 2016.Further investigations by the National In...A recent seismic event was recorded by a deep longwall mine in Virginia at 3.7 ML on the local magnitude scale and 3.4 MMS by the United States Geological Survey(USGS) in 2016.Further investigations by the National Institute for Occupational Safety and Health(NIOSH) and Coronado Coal researchers have shown that this event was associated with geological features that have also been associated with other, similar seismic events in Virginia.Detailed mapping and geological exploration in the mining area has made it possible to forecast possible locations for future seismic activity.In order to use the geology as a forecaster of mining-induced seismic events and their energy potential, two primary components are needed.The first component is a long history of recorded seismic events with accurately plotted locations.The second component is a high density of geologic data within the mining area.In this case, 181 events of 1.0 MLor greater were recorded by the mine's seismic network between January, 2009, and October, 2016.Within the mining area, 897 geophysical logs, 224 core holes, and 1031 fiberscope holes were examined by mine geologists.From this information, it was found that overburden thickness, sandstone thickness, and sandstone quality contributed greatly to seismic locations.After the data was analyzed, a pattern became apparent indicating that the majority of seismic events occurred under specific conditions.Three forecast maps were created based on geology of previous seismic locations.The forecast maps have shown an accuracy of within 74%–89% when compared to the recorded 181 events that were1.0 MLor greater when considering three major geological criteria of overburden thickness of 579.12 m or greater, 6.096–12.192 m of sandstone within 15.24 m of the Pocahontas number 3 seam, and a longwall caving height of 4.572 m or less.展开更多
文摘Jinping traffic tunnel is one of the deepest traffic tunnels in the world with a maximum overburden of 2 375 m and the overburden over 73% of its total length is larger than 1 500 m. The tunnel is 17.5 km long and designed to provide a shortcut road between two hydropower stations： Jinping I and Jinping II of the Jinping Hydropower Project, located on Yalong River, Liangshan State, Sichuan Province, China. The tunnel is so deep that building any shafts is impossible. The construction starts from both ends （east and west ends）, and the construction length from the west end is 10 km with a blind heading. This paper deals with an overview of this project and analysis of the engineering features, as well as key technologies developed and applied during the construction, including geological prediction, rock burst prevention under a super high in-situ stress, sealing of groundwater with a high pressure and big flow rate, ventilation for a blind heading of 10 km, wet spraying of shotcrete at zones of rock burst and rich water, etc. The application of the new technologies to the construction achieved a high quality tunnel within the contract period.
文摘A recent seismic event was recorded by a deep longwall mine in Virginia at 3.7 ML on the local magnitude scale and 3.4 MMS by the United States Geological Survey(USGS) in 2016.Further investigations by the National Institute for Occupational Safety and Health(NIOSH) and Coronado Coal researchers have shown that this event was associated with geological features that have also been associated with other, similar seismic events in Virginia.Detailed mapping and geological exploration in the mining area has made it possible to forecast possible locations for future seismic activity.In order to use the geology as a forecaster of mining-induced seismic events and their energy potential, two primary components are needed.The first component is a long history of recorded seismic events with accurately plotted locations.The second component is a high density of geologic data within the mining area.In this case, 181 events of 1.0 MLor greater were recorded by the mine's seismic network between January, 2009, and October, 2016.Within the mining area, 897 geophysical logs, 224 core holes, and 1031 fiberscope holes were examined by mine geologists.From this information, it was found that overburden thickness, sandstone thickness, and sandstone quality contributed greatly to seismic locations.After the data was analyzed, a pattern became apparent indicating that the majority of seismic events occurred under specific conditions.Three forecast maps were created based on geology of previous seismic locations.The forecast maps have shown an accuracy of within 74%–89% when compared to the recorded 181 events that were1.0 MLor greater when considering three major geological criteria of overburden thickness of 579.12 m or greater, 6.096–12.192 m of sandstone within 15.24 m of the Pocahontas number 3 seam, and a longwall caving height of 4.572 m or less.
