With the development of urban infrastructure,it is inevitable that shield tunnels will undercross intercity railways.However,the safe operation of intercity railways requires strict subgrade deformation.On the basis o...With the development of urban infrastructure,it is inevitable that shield tunnels will undercross intercity railways.However,the safe operation of intercity railways requires strict subgrade deformation.On the basis of the engineering background of the Lianghu Tunnel in Wuhan,the three-dimensional centrifuge test and numerical back analysis were used to study the development of subgrade surface settlement during shield tunneling.A three-dimensional numerical model with the same size as the prototype was subsequently established to further study the settlement development and torsion behavior of the subgrade during tunnel excavation.The results show that the maximum settlement point of the transverse settlement trough gradually moves to the tunnel axis during tunnel excavation and that the entire subgrade experiences torsional deformation.Moreover,the effect of the intersection angle between the axes of the tunnel and the subgrade on the surface settlement of the subgrade was further studied.The results show that the intersection angle has no effect on the maximum settlement,but the width of the settlement trough increases gradually with increasing angle.Finally,on the basis of the soil arching effect caused by tunnel excavation,the subgrade settlement during tunnel excavation is reduced by reinforcing the soil in different zones of soil arching.The results show that the settlement of the subgrade caused by the shield tunnel can be effectively controlled by adding reinforcement directly to the top of the tunnel,and the maximum settlement of the subgrade surface is reduced from 24.41 mm to 9.47 mm,a reduction of approximately 61.2%.展开更多
New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban...New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban construction.This paper presents a two-stage analytical method that considers the asymmetric ground settlement for investigating the longitudinal tunnel responses to new tunnelling.An improved semi-analytical solution considering the horizontal movement of the new tunnel is established for evaluating the tunnelling-induced asymmetric greenfield settlement.The proposed method is verified with field measurement data from a case study.A parametric analysis is conducted to study the influences of the input parameters on the tunnel responses.Results indicate that the horizontal movement of the new tunnel due to bias loading or asymmetric construction may lead to asymmetric responses of the existing tunnel.With increasing tunnel horizontal movement,the asymmetry of the tunnel responses becomes more obvious.An increase in the pillar depth and decreases in the tunnel horizontal movement and skew angle lower the internal forces induced by new tunnelling.展开更多
基金funding support from the National Natural Science Foundation of China(Grant Nos.52208355and 52378308)Shenzhen University's 2035 Program for Excellent Research(Grant No.00000219).
文摘With the development of urban infrastructure,it is inevitable that shield tunnels will undercross intercity railways.However,the safe operation of intercity railways requires strict subgrade deformation.On the basis of the engineering background of the Lianghu Tunnel in Wuhan,the three-dimensional centrifuge test and numerical back analysis were used to study the development of subgrade surface settlement during shield tunneling.A three-dimensional numerical model with the same size as the prototype was subsequently established to further study the settlement development and torsion behavior of the subgrade during tunnel excavation.The results show that the maximum settlement point of the transverse settlement trough gradually moves to the tunnel axis during tunnel excavation and that the entire subgrade experiences torsional deformation.Moreover,the effect of the intersection angle between the axes of the tunnel and the subgrade on the surface settlement of the subgrade was further studied.The results show that the intersection angle has no effect on the maximum settlement,but the width of the settlement trough increases gradually with increasing angle.Finally,on the basis of the soil arching effect caused by tunnel excavation,the subgrade settlement during tunnel excavation is reduced by reinforcing the soil in different zones of soil arching.The results show that the settlement of the subgrade caused by the shield tunnel can be effectively controlled by adding reinforcement directly to the top of the tunnel,and the maximum settlement of the subgrade surface is reduced from 24.41 mm to 9.47 mm,a reduction of approximately 61.2%.
基金The financial support from the National Natural Science Foundation of China(Grant No.51778575)Science and Technology Department of Zhejiang Province(Grant No.2019C03103)。
文摘New tunnelling underneath could influence existing shield tunnels in underground spaces.The evaluation of the influences of tunnelling-induced ground movements on existing tunnels has been a major concern during urban construction.This paper presents a two-stage analytical method that considers the asymmetric ground settlement for investigating the longitudinal tunnel responses to new tunnelling.An improved semi-analytical solution considering the horizontal movement of the new tunnel is established for evaluating the tunnelling-induced asymmetric greenfield settlement.The proposed method is verified with field measurement data from a case study.A parametric analysis is conducted to study the influences of the input parameters on the tunnel responses.Results indicate that the horizontal movement of the new tunnel due to bias loading or asymmetric construction may lead to asymmetric responses of the existing tunnel.With increasing tunnel horizontal movement,the asymmetry of the tunnel responses becomes more obvious.An increase in the pillar depth and decreases in the tunnel horizontal movement and skew angle lower the internal forces induced by new tunnelling.
