Abstract Taking a running tunnel approaching an existing railway bridge as an example, the characteristics of dis? placements induced by metro tunnel construction approaching an existing railway bridge are studied using the Hardening-Soil constitutive model, which compares 3D numerical calculations and site measured results. The following conclusions are made: 1) the rock of a cobble stratum is relatively loose and has poor cementation and stability of the rock mass, and the Hardening-Soil model may be used to simulate the stress-strain relation; 2) vertical displacement induced by running tunnel excavation is mainly concentrated at the tunnel crown and decreases gradually with the increasing of the overburden; 3) surface subsidence induced by the tunnel excavation may be regarded as the superposition of the surface settlement curves of two single-bore tunnels, and the measured values are consistant with the calculated values; 4) the maximum deformations of the existing railway bridge are smaller than the allowable displacements specified in“Railway Line Repair Rules,”and the existing excavation method and support parameters meet the operating conditions for the existing structure regarding its safety; 5) generally the excavation-induced horizontal displacement of the stratum and existing bridge structure is small; and 6) the running tunnel excavation-induced soil disturbance is mainly within the range of 5.4 m around the tunnel.
Abstract：
Taking a running tunnel approaching an existing railway bridge as an example, the characteristics of dis? placements induced by metro tunnel construction approaching an existing railway bridge are studied using the Hardening-Soil constitutive model, which compares 3D numerical calculations and site measured results. The following conclusions are made: 1) the rock of a cobble stratum is relatively loose and has poor cementation and stability of the rock mass, and the Hardening-Soil model may be used to simulate the stress-strain relation; 2) vertical displacement induced by running tunnel excavation is mainly concentrated at the tunnel crown and decreases gradually with the increasing of the overburden; 3) surface subsidence induced by the tunnel excavation may be regarded as the superposition of the surface settlement curves of two single-bore tunnels, and the measured values are consistant with the calculated values; 4) the maximum deformations of the existing railway bridge are smaller than the allowable displacements specified in“Railway Line Repair Rules,”and the existing excavation method and support parameters meet the operating conditions for the existing structure regarding its safety; 5) generally the excavation-induced horizontal displacement of the stratum and existing bridge structure is small; and 6) the running tunnel excavation-induced soil disturbance is mainly within the range of 5.4 m around the tunnel.
LIANG Xiao-Yong- Jin- Jing- Zhang-Chun-Hui
.On Characteristics of Displacements Induced by Approaching Metro Tunnel Construction in a Cobble Stratum[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(1): 110-115
2017, Vol. 54 