Analysis and Design Approach for Concrete Plugs for Underground Storage Caverns

Abstract

In underground crude oil storage facilities, concrete plugs are mainly required to contain crude oil inside caverns and are designed as gas-tight to prevent movement of any oil or vapor across the tunnel, either in a horizontal or vertical direction. Plugs are retained in a key excavated in the rock surface, which provides sufficient bearing to the concrete mass under sustained loading conditions. Construction of plugs involves mass concreting under the typically hot and humid conditions found in underground construction. Therefore, the construction of plugs requires an engineering design that takes into account not only design loads and reinforcement, but also the systematic cooling arrangement and efficient grouting mechanism so that the basic purpose of the plug design is not defeated. This paper discusses the design and construction aspects involved in the construction of large tunnel and shaft plugs for an underground crude oil storage project.