A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnel...A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.展开更多
In order to obtain the seismic responses of the soil-rectangular tunnel structure,based on the PL-Finn constitutive model,four different conditions,namely,the liquefied soil around the rectangular tunnel,the liquefied...In order to obtain the seismic responses of the soil-rectangular tunnel structure,based on the PL-Finn constitutive model,four different conditions,namely,the liquefied soil around the rectangular tunnel,the liquefied soil below the rectangular tunnel,the liquefied soil on either side of the tunnel and the structure on non-liquefied soil,are compared.In accordance to the time at which a large deformation occurs,the possibility of destruction from hard to easy follows a descending order:the liquefied soil all around the structure,the liquefied soil on the bottom of the structure,and the liquefied soil on the two sides of the structure.The area of large deformation is mostly beneath the two arch angles of the tunnel floor.The soil on the two sides,especially close to the structure,is the hardest to liquefy and deform.The large deformation of soil caused by the liquefaction appears after the peak seismic value occurs.The higher the input seismic value is,the easier a large deformation can take place.With the same input of peak ground motion,the total displacement vector of the structure and differential displacement of the side-wall are in accordance with an order from large to small in the three situations:when the saturated sand is on two sides,all around the structure,and on the bottom of the structure.展开更多
China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than ...China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.展开更多
基金supported by the National Natural Science Foundation of China (51678438 & 51308574 & 51478343 & 41672289)the National Basic Research Program of China (2015CB057902)+2 种基金the Shanghai Educational Development Foundation (13CG17)the Shanghai Committee of Science and Technology (13231200503 & 16DZ1200302 & 16DZ1201904)the support from the Fundamental Research Funds for the Central Universities
文摘A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.
基金The National Natural Science Foundation of China(No.41572276)the National Key Research and Development Program of China(No.2017YFC0805400)
文摘In order to obtain the seismic responses of the soil-rectangular tunnel structure,based on the PL-Finn constitutive model,four different conditions,namely,the liquefied soil around the rectangular tunnel,the liquefied soil below the rectangular tunnel,the liquefied soil on either side of the tunnel and the structure on non-liquefied soil,are compared.In accordance to the time at which a large deformation occurs,the possibility of destruction from hard to easy follows a descending order:the liquefied soil all around the structure,the liquefied soil on the bottom of the structure,and the liquefied soil on the two sides of the structure.The area of large deformation is mostly beneath the two arch angles of the tunnel floor.The soil on the two sides,especially close to the structure,is the hardest to liquefy and deform.The large deformation of soil caused by the liquefaction appears after the peak seismic value occurs.The higher the input seismic value is,the easier a large deformation can take place.With the same input of peak ground motion,the total displacement vector of the structure and differential displacement of the side-wall are in accordance with an order from large to small in the three situations:when the saturated sand is on two sides,all around the structure,and on the bottom of the structure.
基金supported by the National Natural Science Foundation of China (Grant No. 51608542)Project of Science and Technology Research and Development Program of China Railway Corporation (Grant No.2015G001-G)
文摘China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.
