The Fenghuoshan Tunnel is an important project in Qinghai-Tibet Railway. How to protect permafrost during tunnelling is one of key technology. There are two kinds of influences on permafrost because of the blasting co...The Fenghuoshan Tunnel is an important project in Qinghai-Tibet Railway. How to protect permafrost during tunnelling is one of key technology. There are two kinds of influences on permafrost because of the blasting construction, firstly, blasting results in the damage of the surrounding rock, producing cranny in surrounding rock or making existing cranny spreading even connecting, secondly, the explosion produces gas with high temperature and high pressure, tremendous heat energy influences the heat balance of permafrost. To minimize the effect on permafrost during explosion construction, this paper has done research for relevant explosion scheme based on the theoretic analysis and spot tests. Pre-crack explosion is adopted on the hollow segment, and smooth explosion is adopted on the tunnel body segment, whole section excavation is adopted on the tunnel body segment with grade Ⅳ surrounding rock, and the face steps excavation is adopted on the tunnel body segment with grade Ⅴ surrounding rock. Explosion parameters were optimised finally. The maximal explosion vibration velocity in the surrounding rock is controlled in 5～10 cm/s. To solve the heat disturbance problem, brine mud is adopted to block up explosion holes in order to coll and dustproof. The research result indicated the explosion gaseous cool effect when the brine mud medium as adopted reached 70% compared to 55% when the water mud medium was adopted, so the gaseous cool effect was very distinct.展开更多
Based on the characteristics of tunnels in permafrost, we established an integrated infromatization management system for the construction of the Fenghuoshan Tunnel Qinghai-Tibet Railway. In addition to information co...Based on the characteristics of tunnels in permafrost, we established an integrated infromatization management system for the construction of the Fenghuoshan Tunnel Qinghai-Tibet Railway. In addition to information collection items of generic tunnels, our emphases were placed on the monitoring of the work face temperature, environment temperature, surrounding rock temperature, frost heave force on lining, water pressure on lining and rock bolt force. According to the work face and environment temperatures during construction, we regulated and controlled the ventilation temperature in fime to guarantee the stabilization of the work face and the construction quality of concrete. According to the changes in surrounding rock temperatures, water pressure and frost heave force on the lining, we could estimate the effectiveness of waterproof and temperature preservation systems. According to the changes in frost heave force on lining and rock bolt force, we could estimate the mechanical effectiveness of support system.展开更多
The major technical difficulties of Fenghuoshan Tunnel were caused by arctic alpine, high altitude and permafrost. Through analysis of the major technical problems of Fenghuoshan Tunnel, this paper explored the design...The major technical difficulties of Fenghuoshan Tunnel were caused by arctic alpine, high altitude and permafrost. Through analysis of the major technical problems of Fenghuoshan Tunnel, this paper explored the designing methods and ways of tunnels in arctic alpine climate, on high altitude and on permafrost regions, to offer reference for the projects of similar nature.展开更多
文摘The Fenghuoshan Tunnel is an important project in Qinghai-Tibet Railway. How to protect permafrost during tunnelling is one of key technology. There are two kinds of influences on permafrost because of the blasting construction, firstly, blasting results in the damage of the surrounding rock, producing cranny in surrounding rock or making existing cranny spreading even connecting, secondly, the explosion produces gas with high temperature and high pressure, tremendous heat energy influences the heat balance of permafrost. To minimize the effect on permafrost during explosion construction, this paper has done research for relevant explosion scheme based on the theoretic analysis and spot tests. Pre-crack explosion is adopted on the hollow segment, and smooth explosion is adopted on the tunnel body segment, whole section excavation is adopted on the tunnel body segment with grade Ⅳ surrounding rock, and the face steps excavation is adopted on the tunnel body segment with grade Ⅴ surrounding rock. Explosion parameters were optimised finally. The maximal explosion vibration velocity in the surrounding rock is controlled in 5～10 cm/s. To solve the heat disturbance problem, brine mud is adopted to block up explosion holes in order to coll and dustproof. The research result indicated the explosion gaseous cool effect when the brine mud medium as adopted reached 70% compared to 55% when the water mud medium was adopted, so the gaseous cool effect was very distinct.
文摘Based on the characteristics of tunnels in permafrost, we established an integrated infromatization management system for the construction of the Fenghuoshan Tunnel Qinghai-Tibet Railway. In addition to information collection items of generic tunnels, our emphases were placed on the monitoring of the work face temperature, environment temperature, surrounding rock temperature, frost heave force on lining, water pressure on lining and rock bolt force. According to the work face and environment temperatures during construction, we regulated and controlled the ventilation temperature in fime to guarantee the stabilization of the work face and the construction quality of concrete. According to the changes in surrounding rock temperatures, water pressure and frost heave force on the lining, we could estimate the effectiveness of waterproof and temperature preservation systems. According to the changes in frost heave force on lining and rock bolt force, we could estimate the mechanical effectiveness of support system.
文摘The major technical difficulties of Fenghuoshan Tunnel were caused by arctic alpine, high altitude and permafrost. Through analysis of the major technical problems of Fenghuoshan Tunnel, this paper explored the designing methods and ways of tunnels in arctic alpine climate, on high altitude and on permafrost regions, to offer reference for the projects of similar nature.
