Burial depth is a crucial factor affecting the forces and deformation of tunnels during earthquakes.One key issue is a lack of understanding of the effect of a change in the buried depth of a single-side tunnel on the...Burial depth is a crucial factor affecting the forces and deformation of tunnels during earthquakes.One key issue is a lack of understanding of the effect of a change in the buried depth of a single-side tunnel on the seismic response of a double-tunnel system.In this study,shaking table tests were designed and performed based on a tunnel under construction in Dalian,China.Numerical models were established using the equivalent linear method combined with ABAQUS finite element software to analyze the seismic response of the interacting system.The results showed that the amplification coefficient of the soil acceleration did not change evidently with the burial depth of the new tunnel but decreased as the seismic amplitude increased.In addition,the existing tunnel acceleration,earth pressure,and internal force were hardly affected by the change in the burial depth;for the new tunnel,the acceleration and internal force decreased as the burial depth increased,while the earth pressure increased.This shows that the earth pressure distribution in a double-tunnel system is relatively complex and mainly concentrated on the arch spandrel and arch springing of the relative area.Overall,when the horizontal clearance between the center of the two tunnels was more than twice the sum of the radius of the outer edges of the two tunnels,the change in the burial depth of the new tunnel had little effect on the existing one,and the tunnel structure was deemed safe.These results provide a preliminary understanding and reference for the seismic performance of a double-tunnel system.展开更多
Based on the engineering background of the contact channel between Shangyang and Gushan of Fuzhou Metro Line 2 undercrossing the existing tunnel line,the freezing temperature field of the contact channel,the displacem...Based on the engineering background of the contact channel between Shangyang and Gushan of Fuzhou Metro Line 2 undercrossing the existing tunnel line,the freezing temperature field of the contact channel,the displacement field of the existing tunnel line and the contact channel with different net distances and horizontal angles are analyzed by ANSYS finite element software and field measurement method.The obtained results indicate that during the freezing period,the temperature drops at different measuring holes are almost the same.The temperature near the bottom freezing tube drops faster than that far from the tube.It is found that the bilateral freezing technique improves the formation of the freezing wall in the intersection area.In this case,the intersection time of the cross-section is 7 days faster than that of the adjacent ordinary section.The change curve of the displacement of the surface uplift in different freezing periods with the distance from the center of the channel is“M”shaped.The maximum uplift displacement at 12 m from channel center is 25 mm.The vertical displacement of the measuring point located above the central axis of the connecting channel is large.The farther the point from the central axis,the smaller the corresponding vertical displacement.When the horizontal angle between the existing tunnel and the connecting channel is less than 60,the existing vertical displacement of the tunnel changes rapidly with the horizontal angle,reaching 0.17 mm/.Meanwhile,when the net distance is less than 6.1 m,the change rate of the vertical displacement of the tunnel is up to 2.4 mm/m.展开更多
基金Scientific Research Fund of Liaoning Provincial Education Department under Grant No.LJKZ0336。
文摘Burial depth is a crucial factor affecting the forces and deformation of tunnels during earthquakes.One key issue is a lack of understanding of the effect of a change in the buried depth of a single-side tunnel on the seismic response of a double-tunnel system.In this study,shaking table tests were designed and performed based on a tunnel under construction in Dalian,China.Numerical models were established using the equivalent linear method combined with ABAQUS finite element software to analyze the seismic response of the interacting system.The results showed that the amplification coefficient of the soil acceleration did not change evidently with the burial depth of the new tunnel but decreased as the seismic amplitude increased.In addition,the existing tunnel acceleration,earth pressure,and internal force were hardly affected by the change in the burial depth;for the new tunnel,the acceleration and internal force decreased as the burial depth increased,while the earth pressure increased.This shows that the earth pressure distribution in a double-tunnel system is relatively complex and mainly concentrated on the arch spandrel and arch springing of the relative area.Overall,when the horizontal clearance between the center of the two tunnels was more than twice the sum of the radius of the outer edges of the two tunnels,the change in the burial depth of the new tunnel had little effect on the existing one,and the tunnel structure was deemed safe.These results provide a preliminary understanding and reference for the seismic performance of a double-tunnel system.
基金This research was supported by the project of Natural Science Foundation of Fujian Province(No.2022J01925)supported by the project of the Fuzhou Science and Technology Plan Project(2021-P-047)supported by the Open Project Program Foundation of Engineering Research Center of underground mine construction,Ministry of Education(Anhui University of Science and Technology)(No.JYBGCZX2021104).
文摘Based on the engineering background of the contact channel between Shangyang and Gushan of Fuzhou Metro Line 2 undercrossing the existing tunnel line,the freezing temperature field of the contact channel,the displacement field of the existing tunnel line and the contact channel with different net distances and horizontal angles are analyzed by ANSYS finite element software and field measurement method.The obtained results indicate that during the freezing period,the temperature drops at different measuring holes are almost the same.The temperature near the bottom freezing tube drops faster than that far from the tube.It is found that the bilateral freezing technique improves the formation of the freezing wall in the intersection area.In this case,the intersection time of the cross-section is 7 days faster than that of the adjacent ordinary section.The change curve of the displacement of the surface uplift in different freezing periods with the distance from the center of the channel is“M”shaped.The maximum uplift displacement at 12 m from channel center is 25 mm.The vertical displacement of the measuring point located above the central axis of the connecting channel is large.The farther the point from the central axis,the smaller the corresponding vertical displacement.When the horizontal angle between the existing tunnel and the connecting channel is less than 60,the existing vertical displacement of the tunnel changes rapidly with the horizontal angle,reaching 0.17 mm/.Meanwhile,when the net distance is less than 6.1 m,the change rate of the vertical displacement of the tunnel is up to 2.4 mm/m.