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Construction Technology for the Shallow Twin-tube Six-lane Multi-arch Tunnel without Middle Drift under Large Unsymmetrical Loading
(1. Xinjiang Beixin Road & Bridge Group Co., Ltd., Urumqi 830002; 2. School of Civil Engineering, Central South University,Changsha 410075; 3. Yunnan Institute of Transportation Planning and Design, Kunming 650011)
Abstract The Jinshan Tunnel of the Chuxiong (Guangtong)-Dali Expressway Expansion Project of Yunnan Nation? al Expressway Network of G56 is a six-lane multi-arch tunnel without middle drift. The tunnel passes laterally through the steep slope with a broken rock stratum. The whole tunnel is of shallow-buried large unsymmetrical loading terrain, and the lower part of the side is close to the existing expressway and township road. The unsymmetrical loading of the portal section at the entrance of the tunnel is particularly serious, and there is a large range of sections with negative burial depth. In order to smoothly carry out the entrance construction of Jinshan Tunnel and avoid the influence of mountain disturbance on the operation of existing highways, a comprehensive technical scheme is put forward from the aspects of tunnel structure, mountain reinforcement and excavation construction: (1) The buried depth section of the tunnel portal is provided with pile cap + thin-walled ear wall structure to provide an external vertical foundation and lateral support to resist the unsymmetrical loading of the mountain. (2) The reinforcement of the upper anchor cable and the lower steel pipe pile enhances the lateral stability of the portal slope; (3) The tunnel portal is constructed by half-open cover cut method to reduce the disturbance of surrounding rocks. The successful implementation of the entrance scheme of Jinshan Tunnel on site not only creates good conditions for the smooth opening of the whole line as planned but also accumulates engineering experience for the construction of the portal section of the large-span multi-arch tunnel without middle drift under large unsymmetrical loading.
Abstract：
The Jinshan Tunnel of the Chuxiong (Guangtong)-Dali Expressway Expansion Project of Yunnan Nation? al Expressway Network of G56 is a six-lane multi-arch tunnel without middle drift. The tunnel passes laterally through the steep slope with a broken rock stratum. The whole tunnel is of shallow-buried large unsymmetrical loading terrain, and the lower part of the side is close to the existing expressway and township road. The unsymmetrical loading of the portal section at the entrance of the tunnel is particularly serious, and there is a large range of sections with negative burial depth. In order to smoothly carry out the entrance construction of Jinshan Tunnel and avoid the influence of mountain disturbance on the operation of existing highways, a comprehensive technical scheme is put forward from the aspects of tunnel structure, mountain reinforcement and excavation construction: (1) The buried depth section of the tunnel portal is provided with pile cap + thin-walled ear wall structure to provide an external vertical foundation and lateral support to resist the unsymmetrical loading of the mountain. (2) The reinforcement of the upper anchor cable and the lower steel pipe pile enhances the lateral stability of the portal slope; (3) The tunnel portal is constructed by half-open cover cut method to reduce the disturbance of surrounding rocks. The successful implementation of the entrance scheme of Jinshan Tunnel on site not only creates good conditions for the smooth opening of the whole line as planned but also accumulates engineering experience for the construction of the portal section of the large-span multi-arch tunnel without middle drift under large unsymmetrical loading.
WANG Mingjiang1 CI Xinhang2 CHEN Junwu3 ZHU Changjiang1 YANG Feng2
.Construction Technology for the Shallow Twin-tube Six-lane Multi-arch Tunnel without Middle Drift under Large Unsymmetrical Loading[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(1): 241-248
2023, Vol. 60 