Assessment of groundwater inflow rate into a tunnel considering groundwater level drawdown and permeability reduction with depth

Joon-Shik  Moon; An-Qi Zheng; Seoyong  Jang

doi:10.9711/KTAJ.2017.19.2.109

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2017 Vol.19, Issue 2 Next Page

Assessment of groundwater inflow rate into a tunnel considering groundwater level drawdown and permeability reduction with depth 터널굴착 중 지하수위 강하 및 깊이별 투수계수 변화를 적용한 지하수 유입량 변화 분석

31 March 2017. pp. 109-120

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Abstract

Groundwater seepage into a tunnel is one of the main causes triggering tunnel collapse and the consequent ground subsidence. Thus, it is important to estimate adequately the groundwater inflow rate and porewater pressure change during tunneling with time elapse. In current practice, Goodman’s analytical solution (or image tunnel method) assuming homogeneous ground condition around a tunnel is commonly used for estimating groundwater inflow rate. However, the generally-used analytical solution for estimating groundwater inflow rate does not consider groundwater level drawdown and permeability change with depth, and the inflow rate can be overestimated in design phase. In this study, parametric study was performed in order to investigate the effect of groundwater level drawdown and permeability reduction with depth, and transient flow analysis was carried out for studying the inflow rate change as well as groundwater level and porewater pressure change around a tunnel with time elapse.

Keywords

Groundwater flow into a tunnel

Groundwater level drawdouwn

Permeability reduction

Transient flow analysis

터널 내 지하수 침투는 터널붕괴와 그에 따른 지반침하의 주요 원인 중 하나이다. 따라서 터널굴착 중 시간에 따른 지하수 침투량과 간극수압 변화를 적절히 예측하는 것이 중요하다. 실무에서는 균질한 지반조건으로 가정하는 Goodman의 산정법을 사용하여 지하수 침투량을 계산하지만, 터널굴착 중 지하수위 강하와 깊이에 따른 투수계수 변화를 고려하지 않아 설계단계에서 지하수 유입량을 과다하게 산정할 우려가 있다. 따라서 본 연구에서는 지하수위 강하 및 깊이별 투수계수의 감소를 적용한 매개변수분석을 통해 지하수 유입량 변화를 분석 비교하였으며, 시간에 따른 지하수 침투량 변화와 지하수위 및 간극수압 분포 변화를 분석하기 위해 비정상류 해석을 수행하였다.

키워드

터널 내 지하수 유입

지하수위 저하

투수계수 감소

비정상류 해석

References

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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 : 19
No :2
Pages :109-120
Received Date : 2017-01-13
Revised Date : 2017-02-03
Accepted Date : 2017-02-15
DOI :https://doi.org/10.9711/KTAJ.2017.19.2.109

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

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