Characteristics of the Tunnel Shield Method
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Release time:
2024-08-06
The shield tunneling method has gained widespread adoption due to its distinct advantages: ① Excavation and lining operations are carried out safely under the protection of the shield, ensuring robust construction safety; ② Underground construction does not disrupt surface traffic, and underwater work beneath rivers maintains unobstructed navigation in the waterway; ③ Construction activities are unaffected by weather conditions; ④ The method generates minimal environmental disturbances such as vibration and noise; ⑤ It causes limited impact on existing ground structures and underground utilities.
Applicable conditions:
In loose, water-bearing strata—or when underground facilities such as tunnels are buried at a depth of 10 meters or greater—the shield tunneling method can be employed.
1. Work shafts are permitted along the alignment for shield tunneling entry and exit, as well as for muck removal and material feeding.
2. The tunnel must have sufficient burial depth, with the overburden depth preferably no less than 6 meters and also not less than the diameter of the shield machine.
3. Relatively homogeneous geological conditions;
4. If it’s a single tunnel, sufficient clearance between tunnels must be maintained. The minimum thickness for reinforcing the soil (or rock) mass sandwiched between tunnels and between tunnels and other structures shall be 1.0 meter horizontally and 1.5 meters vertically.
5. From an economic perspective, the continuous construction length should not be less than 300 meters.
Advantages:
1. Safe excavation and lining, with fast tunneling speed;
2. The entire process of shield tunneling—pushing, muck removal, and segmental lining assembly—can be fully automated, significantly reducing construction labor intensity.
3. Does not affect ground-level traffic and infrastructure, nor does it interfere with underground utilities or other facilities;
4. When crossing the river channel, navigation is not affected; construction is unaffected by seasonal changes or weather conditions such as wind and rain, and there is no noise or disturbance during the process.
5. Constructing long tunnels with significant burial depth in soft, water-bearing strata often offers both technical and economic advantages.
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