The Haidong Tunnel is one of the four soft rock tunnels of the Central Yunnan Water Diversion Project(CYWDP),where large deformation hazards of soft rock occur frequently,which seriously affect construction safety.The...The Haidong Tunnel is one of the four soft rock tunnels of the Central Yunnan Water Diversion Project(CYWDP),where large deformation hazards of soft rock occur frequently,which seriously affect construction safety.The effect of highly prestressed anchor cable support was studied based on the active support test in the No.3 branch tunnel of Haidong Tunnel.Firstly,the geological conditions and failure causes were analyzed on the basis of the results of geological survey,in-situ test,and rock laboratory test.Then,the Mohr circle form of the highly prestressed anchor cable active support theory for the support of bedded rock mass was given in combination with the excavation compensation method.It is considered that the prestress active compensation value required for the bedded rock mass is larger than that for the homogeneous rock mass.The deformations of rock mass under both passive and active supports were analyzed by numerical simulations.Furthermore,the'pressure bubble'mechanical model for anchor cable support of bedded rock mass in Haidong Tunnel is given.Field monitoring results show that the highly prestressed anchor cable support can control rock mass deformation well,with a maximum deformation of about 200 mm.The prestressed anchor cable is effective in the bedded stratum,which makes the stress of rock mass uniform and reduces the risk of failure of steel arches due to local bias.Meanwhile,the expansion of plastic zone was efficiently controlled,which is of positive significance for the overall stability of rock mass.展开更多
基金supported by the China Yunnan Province Major Science and Technology Special Plan Foundation Project(Grant No.202002AF080003)the China Railway No.5 Engineering Group Co.,Ltd.The support is greatly appreciated.
文摘The Haidong Tunnel is one of the four soft rock tunnels of the Central Yunnan Water Diversion Project(CYWDP),where large deformation hazards of soft rock occur frequently,which seriously affect construction safety.The effect of highly prestressed anchor cable support was studied based on the active support test in the No.3 branch tunnel of Haidong Tunnel.Firstly,the geological conditions and failure causes were analyzed on the basis of the results of geological survey,in-situ test,and rock laboratory test.Then,the Mohr circle form of the highly prestressed anchor cable active support theory for the support of bedded rock mass was given in combination with the excavation compensation method.It is considered that the prestress active compensation value required for the bedded rock mass is larger than that for the homogeneous rock mass.The deformations of rock mass under both passive and active supports were analyzed by numerical simulations.Furthermore,the'pressure bubble'mechanical model for anchor cable support of bedded rock mass in Haidong Tunnel is given.Field monitoring results show that the highly prestressed anchor cable support can control rock mass deformation well,with a maximum deformation of about 200 mm.The prestressed anchor cable is effective in the bedded stratum,which makes the stress of rock mass uniform and reduces the risk of failure of steel arches due to local bias.Meanwhile,the expansion of plastic zone was efficiently controlled,which is of positive significance for the overall stability of rock mass.
