• Title, Summary, Keyword: Trenchless method

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Trenchless Repairing-Reinforcing Process of Underground Pipes with Advanced Composite Materials (신소재 복합재료를 이용한 비굴착 지하매설관 보수-보강공법)

  • 진우석;권재욱;이대길;유애권
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.43-48
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    • 2001
  • To overcome the disadvantages of conventional excavation technology, various trenchless (or excavation free, or no-dig) repair-reinforcement technologies have been developed and tried. But trenchless technologies so fat developed have some brawbacks such as high cost and inconvenience of operation. In this study, a repairing-reinforcing process for underground pipes with glass fiber fabric polymer composites using VARTM(Vacuum Assisted Resin Transfer Molding) has been developed. The developed process requires shorter operation time and lower cost with smaller and simpler operating equipments than those of the conventional trenchless technologies. For the reliable operation of the developed method, a simple method to apply pressure and vacuum to the reinforcement was devised and flexible mold technology was tried. Also, resin filling and cure status during RTM process were monitored with a commercial dielectrometry cure monitoring system, LACOMCURE. From the investigation, it has been found that the developed repairing-reinforcing technology with appropriate process variables and on-line cure monitoring has many advantages over conventional methods.

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Trenchless Repairing-Reinforcing Process of Underground Pipes with Advanced Composite Materials (신소재 복합재료를 이용한 비굴착 지하매설관 보수-보강공법)

  • 진우석;권재욱;이대길;유애권
    • Composites Research
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    • v.15 no.1
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    • pp.21-31
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    • 2002
  • To overcome the disadvantages of conventional excavation technology various trenchless (or excavation free, or no-dig) repair-reinforcement technologies have been developed and tried. But trenchless technologies so far developed have some drawbacks such as high cost and inconvenience of operation. In this study, a repairing-reinforcing process for underground pipes with glass fiber fabric polymer composites using VARTM (Vacuum Assisted Resin Transfer Molding) has been developed. The developed process requires shorter operation time and lower cost with smaller and simpler operating equipments than those of the conventional trenchless technologies. For the reliable operation of the developed method, a simple method to apply pressure and vacuum to the reinforcement was devised and flexible mold technology was tried. Also, resin filling and cure status during RTM process were monitored with a commercial dielectrometry cure monitoring system, LACOMCURE. From the investigation, it has been found that the developed repairing-reinforcing technology with appropriate process variables and on-line cure monitoring has many advantages over conventional methods.

Behavior of Lateral Earth Pressure around the Underpass Constructed by the STS Construction Method

  • Jin, Kyu-Nam;Kim, Hyo-Jin;Sim, Young-Jong
    • LHI Journal of Land, Housing, and Urban Affairs
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    • v.7 no.4
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    • pp.271-279
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    • 2016
  • Recently developed trenchless construction methods ensure stability for the ground settlement by inserting steel pipes along the underpass section and integrating steel pipes before ground excavation to form pipe-roof. This study is to confirm the reinforcing effect of pipe-roof by measuring lateral earth pressure acting on the underpass constructed by the STS (Steel Tube Slab) construction method. For this purpose, lateral earth pressure was measured at the left and right side of the pipe-roof after installing earth pressure cells. As a result, lateral earth pressure was measured with considerable reduction because the integrated pipe-roof shared surcharge. Therefore, economic design for the underpass could be expected by sharing design load by pipe-roof. In addition, construction cost was analyzed according to the design-load sharing ratio by pipe-roof. As pipe-roof shares design load by 40%, the total construction cost can decrease by almost 10% in the case of four-lane underpass.

A preliminary study on the use of analytic hierarchy process for selecting a optimum trenchless excavation method (최적의 비개착공법 선정을 위한 계층분석법의 적용에 관한 기초연구)

  • Kang, Tae-Ho;Chang, Soo-Ho;Choi, Soon-Wook;Lee, Chulho;Cho, Jinwoo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.6
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    • pp.685-693
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    • 2015
  • There have been high demands for urban underground structures. However, they should be rapidly constructed while maintaining the functions of adjacent structures and road systems especially in urban areas. In this respect, trenchless excavation methods are considered to very effective in minimizing ground displacements during excavation works. A variety of field conditions such as economic, technical and environmental aspects should be taken into consideration when an optimum trechless excavation method is to be chosen in a given condition. Therefore, this study aims to carry out a fundamental study to select an optimum trenchless excavation method by the decision making technique. Especially, AHP (Analytic Hierarchy Process) which is a kind of a multiple attribute decision making process is adopted to consider the opinions of experts and to derive reliable decision criteria. As a result, the weights of key factors and the most effective trenchless methods for different ground conditions were proposed in this study.

A case study on perforation under Daejeon station building by Front-Jacking method (Front-Jacking공법에 의한 대전역사 하부 관통사례)

  • Kim, Yong-Il;Hwang, Nak-Yeon;Jeong, Du-Seok;Cha, Jong-Hwi;Lee, Nae-Yong
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.195-203
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    • 2006
  • The crossing construction under railroad have two methods which are cut and cover and trenchless method. first, cut and cover method is an extremely limited method concerning non-running time. Whereas, trenchless method is free from restriction such as train speed and running time, and has the strong points of safe and rapid construction. Front Jacking method, one of the trenchless methods, is frequently applied recently due to its stability during construction and vantage of assuring schedule reliability. The procedure is that after minimizing interlocking friction with structure and earth pressure due to jacking the small steel tube, pulling the precast box manufactured at the field in the ground using PC strand and hydraulic Jack. This method is able to be applied regardless of section size and length of box and condition of ground. And that is also pro-environmental. This paper presents the case of Daejeon E. W. perforate Road Project applied with the Front Jacking method.

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An Experimental Study on Flexural Behavior in Framed Structure of P.S.T Method (P.S.T 공법 라멘 구조물의 휨 거동 특성에 관한 실험적 연구)

  • Cui, Jie;Yoon, Jong Nam;Eum, Ki Young;Hong, Sung Nam;Park, Sun Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.2
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    • pp.144-152
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    • 2011
  • The existing underground trenchless methods use reinforcing rod in steel tube to obtain structural stiffness. However, there are some problems such as inconvenience of work and expensive material fee which are resulted from limited working space and reinforcing work. To resolve these problems, a new trenchless method, namely P.S.T method (Prestressed Segment Tunnel Method), is developed which uses joint to connect the steel segment and form erection structure in underground construction. Further, installing strands for prestressing. In order to evaluate the flexural capacity of the P.S.T method structure, experiment was conducted. The parameters considered in the experiment are the span-to-depth ratio, diameter of steel tube at corner, prestressing force and welding of joint. Altogether examining the flexural behavior, the effect of deflection in structure according to different parameters has also been analysised.

A Case Study on Construction of Front-Jacking method in Daejeon E.W. perforate Road Project (대전 동서관통도로 Front-Jacking공법 시공사례)

  • Kim Yong-Il;Hwang Nak-Yeon;Cha Jong-Whi;Jang Sung-Wook;Lee Nai-Yong
    • Proceedings of the KSR Conference
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    • pp.646-654
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    • 2005
  • The crossing construction under railroad have two methods which are cut and cover and trenchless method. First, cut and cover method is an extremely limited method concerning non-running time. Whereas, trenchless method is free from restriction such as train speed and running time, and has the strong points of safe and rapid construction. Front Jacking method, one of the trenchless methods, is frequently applied recently due to its stability during construction and vantage of assuring schedule reliability. The procedure is that after minimizing interlocking friction with structure and earth pressure due to jacking the small steel tube, pulling the precast box manufactured at the field in the ground using PC strand and hydraulic Jack. This method is able to be applied regardless of section size and length of box and condition of soil. And that is also pro-environmental. This paper presents the case of Daejeon E. W. perforate Road Project applied with the Front Jacking method.

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Development of Trenchless Tunneling Method Using Pressurizing Support and Its Field Application (가압식 지보를 이용한 비개착 터널공법 개발 및 현장적용 사례)

  • Kim, Dae-Young;Lee, Hong-Sung;Sim, Bo-Kyoung
    • Journal of the Korean Geotechnical Society
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    • v.28 no.7
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    • pp.17-30
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    • 2012
  • A new trenchless tunneling method using pressurizing support has been developed. As it overcomes shortcomings of conventional methods, it is applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies the pressure corresponding to the magnitude of the relaxed earth pressure caused by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through several ways such as numerical tests and various model tests. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long road tunnel that passes under Yeongdong Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months. It decreases the construction period to 35% compared to that of conventional methods, and ground displacement was almost negligible.

Restoration Efficiency Analysis of Expansive Material Implemented Trenchless Underground Cavity Restoration Method Varying Number and Location of Bore Holes (팽창재료를 이용한 지하 공동 비개착 복구공법에서 천공 개수 및 위치에 따른 복구효율 분석)

  • Choi, Byeong-Hyun;Lee, Kicheol;Lee, Junwon;Kim, Dongwook
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.25-37
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    • 2019
  • The conventional representative underground cavity restoration methods, which are mainly open-cut methods, require high cost and long period of time for the restoration. Therefore, various trenchless restoration methods have been proposed to improve these disadvantages. The underground cavity restoration method using the expansive material proposed in this paper is one of the trenchless methods. This method fills the underground cavity with high quality backfill soils through the small hole(s) at asphalt layer and compacts backfill soils by insertion of the expansive material within the cavity. In this study, the restoration method using expansive material was constructed in acrylic chamber. The restoration efficiency of the method was analyzed by the fill ratio and degree of relative compaction according to the location and number of bore holes. As a result of the experiment, the restoration efficiency and the optimum construction location were found to be irrelevant.

Experimental analysis for the effect of integrated pipe-roof in trenchless method (비개착 일체형 파이프루프 지보효과의 실험적 분석)

  • Sim, Youngjong;Jin, Kyu-Nam
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.5
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    • pp.377-387
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    • 2016
  • In recent, in case that the underpass is constructed by trenchless method, its stability increases by reinforcing steel pipe with re-bar and mortar after propulsion into the ground to form pipe-roof. Therefore, it can be predicted that the integrated pipe-roof decreases the stress acting on the underpass by sharing load. In this study, to analyze the effect of integrated pipe-roof and behavior of stress around underpass, experimental tests for the rectangular and arch cross section of the underpass are performed using soil chamber. As a result, stress and strain acting on the underpass decrease due to sharing load by integrated pipe-roof. This phenomenon is more pronounced by increasing the stiffness of pipe-roof. Furthermore it can be expected that cross-section of underpass can be economically designed.