• Title, Summary, Keyword: Integrated pipe-roof

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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.

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.

Analysis on the characteristics of the earth pressure distribution induced by the integrated steel pipe-roof construction (일체형 강관 파이프루프 시공에 따른 주변 지반의 토압 분포 특성 분석)

  • Sim, Youngjong;Jin, Kyu-Nam;Song, Ki-Il
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.5
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    • pp.455-468
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    • 2013
  • In recent, various types of steel pipe-roof methods, which is reinforced by mortar after propulsion of steel pipe into the ground, have been used for the construction of trenchless underpass. Integrated steel pipe-roof has flexural stiffness and can resist against overburden load and reduce the stress acting on the concrete underpass structures. Due to arching effect, vertical and horizontal stress distribution around the steel pipe-roof is changing. In this study, therefore, the characteristic of stress distribution around the underpass induced by the construction of integrated steel pipe-roof is investigated by using numerical method. To examine the soil-structure interaction, interface element is introduced. Results show that vertical stress acting on the concrete structure placing inside the steel pipe-roof is significantly reduced due to arching effect and flexural stiffness of integrated steel pipe-roof. Design load can be reduced and effective design of underpass will be available if the earth pressure reduction due to arching effect is considered in the design stage.