Abstract
References
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Numerical modeling is usually used for the verification of gas tightness in underground LPG facilities. Generally, comparing with the size of regional groundwater system including LPG facilities, that of water curtain boreholes is too small. As a result, the grid refinement modeling is impossible or very inefficient. In this research, combination modeling has been proposed. Firstly the region of concern is defined in order to evaluate head distribution. And the inflow to and outflow out of the concerned region are able to be estimated by global modeling with global water boundaries. These water inflow and outflow quantities become new boundary conditions for local modeling of the concerned region. Finally the local modeling is conducted where the grid is refined to represent exactly real sizes of water curtain boreholes. The combination modeling was applied to the gas tightness analysis of Visakhapatnam underground LPG facilities in India, and then was compared with only global modeling. The vertical hydraulic gradients of combination modeling were 9～46% lower than those of global modeling. It means that the only global modeling without grid refinement might overestimate the safety on gas tightness. Unforturenately, if only the global modeling is conducted for verification of water curtain system, which does not meet the criteria of gas tightness or has a bit of hydraulic margin, the global modeling is likely to arrive at the wrong conclusion that this water curtain system is safe enough.
지하 LPG 비축기지의 기밀성 검증을 위해 수치전산모델링을 수행할 때 대상지역을 포함하는 광역수계에 비해 수벽공 등 지하비축기지의 구성요소가 너무 작아 격자세분화에 의해 모델링을 수행하기 어려운 문제점이 있다. 이에 본 연구에서는 집중적으로 수두분포를 확인해야 하는 관심영역을 설정한 후 광역수계에서의 전체모델링을 선수행하여 관심영역으로의 지하수 유출입량을 산출함으로서 이를 관심영역의 외곽경계조건으로 재설정해 수벽공의 실제크기 그대로 격자를 세밀하게 분화시켜 국지적으로 재모델링 하는 조합모델링 방법을 제시하였다. 인도 Visakhapatnam 지하 LPG 비축기지 프로젝트에 조합모델링 방법을 적용하여 광역적 모델링 결과와 비교하였다. 조합모델링의 결과, 기밀성의 평가척도인 수직동수구배가 광역적 모델링에 비해 9～46% 작게 평가되었다. 즉 격자세분화 없이 수행된 광역모델링이 안전율을 과대평가 하는 것이다. 기밀성 기준을 만족 못시키거나 수리학적 여유가 거의 없이 설계된 수벽시설을 광역적 모델링 만으로 검증했을 경우 충분한 안전율이 확보된다는 잘못된 결과가 도출될 수 있는 것이다.
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- Publisher :The Korean Society of Mineral and Energy Resources Engineers
- Publisher(Ko) :한국자원공학회
- Journal Title :Journal of the Korean Society for Geosystem Engineering
- Journal Title(Ko) :한국지구시스템공학회지
- Volume : 42
- No :4
- Pages :345-353
Journal of the Korean Society of Mineral and Energy Resources Engineers
