• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.393-402
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• 2021

The first TBM introduced in Korea was the gripper TBM, which was applied to the Gudeok Waterway Tunnel in 1985. In the initial stage of the introduction of the gripper TBM, many applications were mainly focused on waterway tunnels (Tunnel Mechanized Construction Design, 2008). Currently, the construction range of gripper TBM in Korea is widely applied to not only waterway tunnels, but also subways, railway tunnels, and TBM+NATM expansion. Overseas, gripper TBM is generally applied, and even when NATM tunnel is applied, it is applied as an exploration tunnel because of the excellent advance rate of gripper TBM and used as an evacuation tunnel after completion. Due to the fast excavation speed, the application of the gripper TBM in the rock section of weathered rock or higher can minimize the environmental and civil complaints caused by creating a large number of work areas when planning long tunnels or mountain tunnels. In this study, the work process of the general gripper TBM was analyzed by analyzing the construction cycle and the gripper TBM with a diameter of 2.6~5.0 m, which was applied the most in Korea. Downtime was investigated and analyzed.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.413-420
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• 2024

When planning gripper TBM, which is highly applicable to urban areas, the excavation characteristics are not considered. In addition the excavation stability and constructability are degraded by installing reinforcements in the adjacent construction site considering the relaxation load theory of the pre-existing NATM. In this study, a rationalization plan for the support was proposed considering the excavation characteristics of gripper TBM when planning reinforcements for adjacent pre-existing construction. The effect of excavation on the surrounding ground was analyzed by conducting three-dimensional stability analyses considering the construction stage for each excavation phase. In NATM, relaxation phenomenon is concentrated in tunnel face due to non-supporting time occurring simultaneously with excavation, but gripper TBM supports the ground around the tunnel face through the cutter head and skin plate, simultaneously causing ground relaxation behind the skin plate. Considering these excavation characteristics, problems in reinforcement planning for adjacent construction at the study site were pointed out. A performance improvement plan for a reasonable supporting system was proposed.