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Construction of long and large twin tube tunnel in Korea–Sapaesan tunnel
Tunnelling and Underground Space Technology incorporating Trenchless Technology Research
Tunnelling and Underground Space Technology 21 (2006) 393
www.elsevier.com/locate/tust
Construction of long and large twin tube tunnel in Korea–Sapaesan tunnel Sang-lim No, Seung-hwan Noh, Sang-pil Lee, Jeong-woo Seo GS Engineering and Construction Corporation, Seoul, Korea
In 1989, the Korea government decided to construct Seoul Beltway, radius of 15–20 km from the center of Seoul, to solve the heavy traffic congestion in Seoul Metropolitan Area. The construction of southern section of the Beltway with the length of 91 km linking Taegyewon, Pangyo and Ilsan was finished and are currently open to the public. However, a 36 km-long northern section including the Sapaesan tunnel is still under construction due to the strong opposition by environmental and religious bodies. Therefore, the maximization of construction efficiency is demanded in Sapaesan tunnel project to compensate for the delayed time to complete the northern section. The Sapaesan tunnel, the 4 km twin tunnel with 4 lanes, is the longest 4-lane road tunnel in Korea, and connects Yangju and Eijeongbu in northern section. The internal area of the tunnel is 170.04 m2 and total excavation volume is about 1,370,000 m3. NATM (new Austrian tunnelling method) is adopted for tunnel excavation and Q-system has been applied to divide excavation pattern. Three electrical smoke and dust collectors were added to ventilation system with 30 jet fans (B1, 530 mm) considering tunnel length. For safety of tunnels, 5 cross passage and 12 emergency parking lots were designed. To shorten the construction time of the Sapaesan tunnel, each tunnelling process (excavation, mucking, support and concrete lining) was carefully examined and three main subjects were proposed; increasing tunnel cycle length, changing excavation sequence and simultaneous working of concrete lining. The 3D FEM analysis was carried out to confirm tunnelling stability, and tunnel cycle length was extended to 1–1.5 m for support type of TYPE I, TYPE II and TYPE III compared to original cycle length. TSP (tunnel seismic prediction) survey was performed for predicting tunnel face ahead and the deformation after excavation was monitored with electro optical distance meter. In case of extending tunnel cycle length with increasing volume of charging explosives, it is expected to decrease blast efficiency and widen over break. Therefore, bulk-emulsion explosive and cylinder-cut method with two bull holes (B127 mm) were adopted in tunnel blasting to maximize blast efficiency. The excavation sequence was originally designed to excavate bench after penetrating the crown of tunnel. However, this sequence takes a long construction time because of the length and width of the Sapaesan tunnel. To shorten the construction period, some modifications in the excavation sequence were carried out; crown excavation without partition and simultaneous excavation of crown and bench. In Korea, concrete structures for utilities and tunnel lining are usually set up after finishing excavation in the road tunnel construction because blast-vibration could influence the strength of structures or cause crack in concrete. However, setting up concrete structures after excavation could delay construction in long length tunnel. Therefore, the setting up concrete structures synchronized with excavation was planned to reduce construction time. Concrete lining was installed behind moveable temporary walls installed next to cross passage. With these continuous efforts, the construction period of the Sapaesan tunnel is expected to be shortened by more than 10 months. If the Sapaesan tunnel construction is finished early, the northern section of Seoul Beltway will be finalized and the heavy traffic congestion in northern Gyeonggi area will be solved with remarkable development. There has been huge request for constructing tunnel with long distance and large cross section. We hope that our efforts for the Sapaesan tunnel construction may contribute to advancement of the tunnelling technology in Korea. Keywords: Cycle length; Excavation sequence; Simultaneous working; Bulk-emulsion explosive
doi:10.1016/j.tust.2005.12.204
Tunnelling and Underground Space Technology 21 (2006) 393
www.elsevier.com/locate/tust
Construction of long and large twin tube tunnel in Korea–Sapaesan tunnel Sang-lim No, Seung-hwan Noh, Sang-pil Lee, Jeong-woo Seo GS Engineering and Construction Corporation, Seoul, Korea
In 1989, the Korea government decided to construct Seoul Beltway, radius of 15–20 km from the center of Seoul, to solve the heavy traffic congestion in Seoul Metropolitan Area. The construction of southern section of the Beltway with the length of 91 km linking Taegyewon, Pangyo and Ilsan was finished and are currently open to the public. However, a 36 km-long northern section including the Sapaesan tunnel is still under construction due to the strong opposition by environmental and religious bodies. Therefore, the maximization of construction efficiency is demanded in Sapaesan tunnel project to compensate for the delayed time to complete the northern section. The Sapaesan tunnel, the 4 km twin tunnel with 4 lanes, is the longest 4-lane road tunnel in Korea, and connects Yangju and Eijeongbu in northern section. The internal area of the tunnel is 170.04 m2 and total excavation volume is about 1,370,000 m3. NATM (new Austrian tunnelling method) is adopted for tunnel excavation and Q-system has been applied to divide excavation pattern. Three electrical smoke and dust collectors were added to ventilation system with 30 jet fans (B1, 530 mm) considering tunnel length. For safety of tunnels, 5 cross passage and 12 emergency parking lots were designed. To shorten the construction time of the Sapaesan tunnel, each tunnelling process (excavation, mucking, support and concrete lining) was carefully examined and three main subjects were proposed; increasing tunnel cycle length, changing excavation sequence and simultaneous working of concrete lining. The 3D FEM analysis was carried out to confirm tunnelling stability, and tunnel cycle length was extended to 1–1.5 m for support type of TYPE I, TYPE II and TYPE III compared to original cycle length. TSP (tunnel seismic prediction) survey was performed for predicting tunnel face ahead and the deformation after excavation was monitored with electro optical distance meter. In case of extending tunnel cycle length with increasing volume of charging explosives, it is expected to decrease blast efficiency and widen over break. Therefore, bulk-emulsion explosive and cylinder-cut method with two bull holes (B127 mm) were adopted in tunnel blasting to maximize blast efficiency. The excavation sequence was originally designed to excavate bench after penetrating the crown of tunnel. However, this sequence takes a long construction time because of the length and width of the Sapaesan tunnel. To shorten the construction period, some modifications in the excavation sequence were carried out; crown excavation without partition and simultaneous excavation of crown and bench. In Korea, concrete structures for utilities and tunnel lining are usually set up after finishing excavation in the road tunnel construction because blast-vibration could influence the strength of structures or cause crack in concrete. However, setting up concrete structures after excavation could delay construction in long length tunnel. Therefore, the setting up concrete structures synchronized with excavation was planned to reduce construction time. Concrete lining was installed behind moveable temporary walls installed next to cross passage. With these continuous efforts, the construction period of the Sapaesan tunnel is expected to be shortened by more than 10 months. If the Sapaesan tunnel construction is finished early, the northern section of Seoul Beltway will be finalized and the heavy traffic congestion in northern Gyeonggi area will be solved with remarkable development. There has been huge request for constructing tunnel with long distance and large cross section. We hope that our efforts for the Sapaesan tunnel construction may contribute to advancement of the tunnelling technology in Korea. Keywords: Cycle length; Excavation sequence; Simultaneous working; Bulk-emulsion explosive
doi:10.1016/j.tust.2005.12.204