• Title/Summary/Keyword: tunnel enlargement

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A study on the enlargement of 2-lane road tunnel under construction (시공중인 2차로 도로터널의 확장 방안에 대한 연구)

  • Choi, Hae-Jun;Kim, Dae-Kyu
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.1
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    • pp.33-50
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    • 2011
  • Recently interest in enlargement of existing tunnel located in downtown or mountain area have been considerably increased along with requirements and discussion on the road-widening. Therefore, it is necessary to study the construction method and stability of tunnel to enlarge the existing tunnel in design. In this study, the design concept on the alignment, excavation method, reinforcement to enlarge the existing tunnel is described on the basis of the enlargement of 2-lane road tunnel under construction. This paper suggests a proper design method for the enlargement of an existing tunnel in useful practice.

Analysis of traffic volume for control during an existing tunnel enlargement (발파에 의한 터널확대 굴착 시 교통처리를 위한 교통량 분석)

  • Kim, Woong-Ku;Baek, Ki-Hyun;Seo, Kyoung-Won
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.1328-1332
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    • 2010
  • The enlargement of existing tunnels is required to cope with problems related to traffic congestion. Sometimes, the tunnel traffic must be maintained through existing tunnels during their reconstruction due to non-availability of detours. And excavation by drill and blasting is desired for widening a hard rock tunnel. In this case, the road must be closed for some period for blasting through analyzing of traffic volume. In this paper, a case study on some traffic countermeasures for tunnel enlargement by blasting was performed. And the traffic flow characteristics of some tunnels in domestic main city were analyzed.

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Tibial Tunnel Enlargement following Arthroscopic ACL Reconstruction (관절경하 전방십자인대 재건술 후 경골 터널 크기 변화)

  • Lee, Kwang-Won;Lee, Byeong-Ki;Ryu, Chang-Soo;Keum, Teok-Seop;Choy, Won-Sik
    • Journal of the Korean Arthroscopy Society
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    • v.2 no.2
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    • pp.114-118
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    • 1998
  • We retrospectively evaluated the changes in the diameter of the tibial tunnel over time following the reconstruction of the anterior cruciate ligament with a bone-patella tendon-bone(BPTB) autograft(25 cases) and quadruple semitendinosus(ST) graft(27 cases) in 52 patients at one year postoperatively. The changes in the geometry of the bony tunnel were measured with radiography. The demensions at final follow up were correated with the clinical results. An increased width of the tibial tunnel was noted in all cases. On the femoral side, however, no tunnel expansion was noted. In AP view, the average tibial tunnel enlargement in ST and BPTB graft groups were 1.30mm(13%) and 1.82mm(17%), respectively. In lateral view, the average tibial tunnel enlargement in ST and BPTB graft group was 1.30mm(13%) and 2.04mm(19%). The differences between two groups were not statistically significant, however, there was evidence of a borderline significance(P=0.0502). Although the tunnel enlargement does not appear to adversely affect the clinical outcome in the short term, the exact mechanism which are involved should be demonstrated. Furthermore histologic study is needed to evaluate graft replacements with emphasis on the graft-tunnel interface.

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The numerical study on the ground settlement behavior of box type tunnel enlargement (2차원 수치해석을 통한 초저심도 박스형 터널 편측확폭시 지반침하거동 특성 분석)

  • Cha, Yohan;Cho, Gye-Chun;Hong, Eun-soo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.1
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    • pp.83-94
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    • 2016
  • Utility tunnels have been employed in Korea since the 1970s and start to make trouble with structural safety and serviceability. Recently, tunnel enlargement has consequently been proposed due to the impending problems. However there are little study on box type utility tunnels except traffic tunnels. A 2D finite element analysis was conducted to evaluate ground behavior which depends on enlargement size and stiffness by one-side enlargement of the utility tunnel. Settlement scale increased with larger enlargement size and less stiff ground conditions. The observed settlement characteristics due to enlargement are similar to that suggested by Clough & Schmidt (1981). The settlement width is more affected by enlargement size than ground condition.

A study on the social cost estimation of the tunnel section enlargement method considering traffic flow (교통흐름을 고려한 터널단면 확대 시공기술의 사회적 손실비용 산정에 관한 연구)

  • Lee, Seung Soo;Kim, Dong-Gyou;Seo, Jong Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.4
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    • pp.487-497
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    • 2015
  • Using existing tunnel for section enlargement and remodeling is being considered as an optimal alternative in order to solve traffic jam in tunnel. The existing method has been performed while blocking the traffic flow. Recently, New enlargement method was developed which can maintain traffic flow during the construction by using protector. It can minimize social loss due to keeping traffic flow. On the other hand, installing and operating protector can cause economic disadvantages. So, social cost estimation considering traffic flow should be considered for relevant economic evaluation of tunnel section enlargement methods. This paper presents the social cost estimation method of tunnel section enlargement methods considering traffic flow. In addition, to compare economic efficiency existing method with new method, suggested method was applied to Maebong Tunnel.

Development of New Drill and Blast Method with Two Different Drilling Directions for Pilot Tunnel Enlargement (터널확공시 이방향 병용천공 발파공법의 개발)

  • 배규진;문홍득
    • Proceedings of the Korean Geotechical Society Conference
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    • 1994.09a
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    • pp.199-208
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    • 1994
  • This paper presents an evaluation of new drill and blast method with two different drilling directions for pilot tunnel enlargement using numerical experiment and field test. To evaluate the effieiency of new tunnel enlargement method, field tests were performed and compared with conventional drill and blast method. Also, three dimensional transient dynamic analysis was made to investigate the effect of the ground vibration when blasting was performed at same position using the equivalent single hole charge.

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Economic Feasibility Analysis of a Tunnel Section Enlargement Method That Does Not Halt Traffic Flow (교통류 보존형 터널단면 확대 시공기술의 경제적 타당성 분석)

  • Lee, Seung Soo;Kim, Dong-Gyou;Seo, Jong Won
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.459-472
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    • 2015
  • A recently developed tunnel section enlargement method can maintain traffic flow during construction by using a protector. By keeping traffic flowing, it can minimize the lost time and costs associated with diversions and also the accompanying environmental pollution. On the other hand, installing the protector can lengthen the construction period and increase the direct cost. This paper presents a method for analyzing the economic feasibility of tunnel section enlargement methods considering the direct construction cost and the indirect social cost. The indirect costs are divided into categories of: vehicle driving cost, travel time delay cost, and environmental pollution cost. The economic efficiency of existing technology is compared with the new method in an case study of Namsan Tunnel 3.

Numerical Analysis for Shotcrete Lining at SCL Tunnel in NS2 Transmission Cable Tunnel Project in Singapore (싱가포르 케이블터널 프로젝트 NS2현장 SCL 터널에서의 숏크리트 라이닝의 변형거동 특성)

  • Kwang, Han Fook;Kim, Young Geun
    • Tunnel and Underground Space
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    • v.27 no.4
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    • pp.185-194
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    • 2017
  • This technical paper is a study on the unique displacements of Shotcrete Lining at the mined tunnel during excavation period through deep consideration with real time data from monitoring instrumentations correlation with the numerical analysis to identify the rock stresses and the rock spring points at the working face of the Conventional tunnelling by the Drill and Blast, based on the geological face mapping results of the project NS2, Transmission cable tunnel project in Singapore. The created geometry of numerical model was prepared to the real mined tunnel construction site including, vertical shaft, construction adit, tunnel junction area, and 2 enlargement caverns. The convergence measurements by the monitoring instrumentation were performed during the tunnel excavation and shaft sinking construction stages to guarantee the safety of complicated underground structures.

Reinforcement of Shotcrete Lining on the Side Wall of Tunnel in Enlargement of Existing ASSM Road Tunnel (측벽부 숏크리트 보강에 의한 재래식 도로터널 단면확대)

  • Kim, Donggyou;Shin, Youngwan
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.12
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    • pp.81-89
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    • 2012
  • The existing tunnel in urban area can be enlarged because of requirement of road-widening by traffic growth. The protector with rectangular cross section can be set up in the tunnel, which will be constructed for enlargement of width, to solve traffic jam around the tunnel. It is impossible to install the rockbolt in the lower area of tunnel due to a limited space between the protector and cutting surface. The objective of this study is to suggest the method of shotcrete thickness increase instead of rockbolt installation in the side wall of tunnel for the stability of tunnel. Numerical analysis was performed to evaluate displacement at the crown of tunnel, convergence of tunnel, and stress in shotcrete lining in 3-lane and 4-lane NATM tunnels enlarged from 2-lane conventional tunnel. There were three types of analysis condition, rockbolt installation, no rockbolt installation, and increase of shotcrete thickness without rockbolt in the side wall of tunnel. There was no difference on the displacement at the crown and the convergence of upper tunnel. In the lower tunnel, the convergence in case of no rockbolt installation was larger as maximum 1.3mm than that in case of rockbolt installation. The stress in shotcrete lining in case of no rockbolt installation was larger as maximum 1.3MPa than that in case of rockbolt installation. Numerical analysis was performed to compare the behavior of shotcrete with rockbolt with that of shotcrete, which its thickness was increased, without rockbolt. The shotcrete has an increase of 20%(250mm ${\rightarrow}$ 300mm, 4-lane tunnel)~25%(200mm ${\rightarrow}$ 250mm, 3-lane tunnel) in its thickness to reduce the stress in shotcrete lining. The behavior of shotcrete lining increased the shotcrete thickness by 20%~25% was similar to that of existing shotcrete lining with rockbolt.

Section enlargement by reinforcement of shotcrete lining on the side wall of operating road tunnel (운영중인 도로터널의 측벽하부 숏크리트 보강에 의한 단면확대)

  • Kim, Dong-Gyou;Shin, Young-Wan;Shin, Young-Suk
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.14 no.6
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    • pp.637-652
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    • 2012
  • The protector with the shape of '${\sqcap}$' in cross section can be set up in the tunnel, which can be constructed for enlargement of cross section, to keep traffic flow in the tunnel. It is impossible to install the rockbolt in the side wall of tunnel due to a limited space between the protector and cutting surface of side wall. The objective of this study is to suggest the optimum thickness of shotcrete lining without rockbolt on the side wall and to evaluate the stability of tunnel enlarged. Numerical analysis was performed to evaluate the displacement at the center of tunnel, the convergence of tunnel, and the stress in shotcrete lining in 4-lane NATM road tunnel enlarged from 3-lane NATM road tunnel. The vertical displacement at the center of tunnel and the convergence of crown in the tunnel with rockbolt in the side wall were almost similar to those in the tunnel without rockbolt in the side wall. The convergence of bench/invert and the stress in shotcrete lining without rockbolt on the side wall were greater maximum 0.57 mm and 1,300 kN/$m^2$ than those with rockbolt in the side wall. The increased convergence and the stress in shotcrete lining can be reduced in incerasing of thickness of shotcrete lining about 20% (5 cm) of standard thickness, 25 cm, of shotcrete lining.