• Tunnel and Underground Space
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• v.7 no.2
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• pp.136-142
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• 1997

The behaviour of ground movement during the construction of two parallel tunnels in weathered zone and soft rock has been investigated. All the influencing factors for the behaviour of twin tunnel such as tunnel size, ground conditions, tunnel depth, pillar width and initial state of ground stresses were examined The results of FEM nonlinear analysis were compared with some of model test results in weathered zone to verify the numerical method. It was found that minimum interference was obtained in the parallel construction case when the twin tunnel distance (pillar width) is just over the twice of tunnel diameter. Guide line for the interference of twin tunnelling has been introduced for the ground of weathered zone and soft rock.

• Explosives and Blasting
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• v.8 no.4
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• pp.3-22
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• 1990

The $\varphi{4.5}$ meters pilot tunneling work is almost done to the $\varphi{11.3}$ meters twin tunnel of NAM SAN No1. The south side pit of 400 meters is weak zone of Rock status, so client request us to allow the cautious blasting pattern for drilling on the condition of 0.2 kine vibration allowance limited for the safety of side running tunnel. The pattern of cautious blasting carried out by 6 time divided fiving on the round drilling depth of 1.20 meters(1.10) and also applied control blasting method with line drilling due to the reduction of vibration.