A study on the optimum range of reinforcement in tunneling adjacent to structures

Hong-Sung Lee; Dae-Young Kim; Byung-Sik Chun; Hyuk-Sang Jung

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2009 Vol.11, Issue 2 Preview Page

A study on the optimum range of reinforcement in tunneling adjacent to structures 구조물 근접 터널시공시 최적의 보강범위에 관한 연구

30 June 2009. pp. 199-211

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Abstract

Development of underground space is actively performed globally for better life in the surface, and the scale of the space is increasing. Extreme care should be taken in the construction of the underground space in urban areas in order to avoid damage of adjacent structures and interference with existing underground space. In case of shallow tunnels, reinforcement of ground and structures is necessary to minimize the damage to structures due to excavation but any standard for optimum range of the reinforcement has not been established yet. In this paper, a series of numerical analyses have been performed for a 20 m diameter tunnel excavated underneath a structure to investigate the degree of damage of the structure according to vertical and horizontal spacing between the tunnel and structure. In addition to that, optimum range of reinforcement is presented for each case where reinforcement is required. It has been observed that the reinforcement is necessary for the ground condition adapted in the analyses as follows: (1) if horizontal spacing (SH) approaches to 0D (D: equivalent diameter of tunnel) for vertical spacing (SV) of 0.5D, and (2) if tunnel exists underneath the structure for vertical spacing (SV) of 0.75D. The reinforcement is not necessary for SV of 1D regardless of SH. It also has been obtained that the optimum ranges of the reinforcement around structure foundation are 7 m in depth and whole width of the structure and 5 m beyond tunnel sidewall. These reinforcememt ranges have been confirmed to be enough for stability of the structure if types of reinforcement method is appropriately selected.

Keywords

Tunneling adjacent to structure

range of reinforcement

numerical analysis

쾌적한 지상공간의 삶을 위하여 전세계적으로 지하공간 개발이 활발히 이루어지고 있으며, 그 규모도 점차 대형화하고 있는 추세이다. 하지만 밀집한 상부 구조물에 대한 피해 우려와 기존 지하공간과의 간섭 등으로 인하여 새로운 지하공간 건설 시 많은 주의가 필요한 실정이다. 천층에 굴착되는 터널의 경우, 굴착으로 인한 상부 구조물의 피해를 최소화하기 위하여 구조물 하부 및 터널 주변지반의 보강이 필수적이나 그 적정범위에 대한 기준은 마련되어있지 않은 실정이다. 본 논문에서는 직경 20 m의 대단면 터널이 구조물 하부에 시공되는 경우에 대해서 수치해석을 실시하여, 터널과 구조물간의 수직 및 수평이격거리에 따른 구조물 피해정도를 조사하였고 보강이 필요한 경우에는 각각의 경우별로 최적의 보강범위를 제시하였다. 본 논문에서 다룬 지반조건에 대한 해석결과, 수직이격거리가 0.5D(D: 터널등가직경)인 경우에는 수평이격거리가 0D에 근접하면서부터 보강이 필요한 것으로 나타났으며, 수직이격거리가 0.75D인 경우에는 터널이 구조물 하부에 위치할 때 보강이 필요하였다. 또한 수직이격거리가 1D 이상인 경우에는 수평이격거리에 상관없이 보강이 필요 없는 것으로 나타났다. 구조물 기초지반 보강범위는 깊이 7 m, 폭은 구조물 전체를 포함하여 터널 측벽에서 5 m 벗어난 곳까지이다. 상황에 따라 적절한 보강공법을 선택하였을 경우, 이와 같은 보강범위는 구조물 안정에 충분한 것으로 나타났다.

키워드

구조물 근접시공

보강범위

수치해석

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Information

Publisher :Korean Tunneling and Underground Space Association
Publisher(Ko) :한국터널지하공간학회
Journal Title :Journal of Korean Tunnelling and Underground Space Association
Journal Title(Ko) :한국터널지하공간학회 논문집
Volume : 11
No :2
Pages :199-211
Received Date : 2009-05-21
Revised Date : 2009-05-28
Accepted Date : 2009-06-02

Journal of Korean Tunnelling and Underground Space Association ISSN:2233-8292(Print) 2287-4747(Online) 한국터널지하공간학회 논문집

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