ABSTRACT
Namikata and Kurashiki underground LPG storage caverns apply natural groundwater with artificial hydraulic containment system to preserve the LPG at high pressure and normal temperature (e.g. Propane, 0.73MPaG at 20°C). The water curtain galleries and water curtain boreholes were designed to maintain the surrounding pore pressure higher than the storage pressure and to ensure the groundwater flow toward the storage caverns constantly. Therefore, the constitution of storage caverns under high water pressure has to be discussed throughout the construction phase, commissioning and operation phase. Pore pressure sensors, acoustic emission sensors, vibration sensors and accelerometers were installed in the caverns to ensure the rock mechanical stability. These monitoring and measurement are launched from the water curtain compression test, the access tunnel water filling and the cavern air tightness test, and are continued even in the operation phase. Based on the measurement results, the storage caverns have been evaluated the integrity.
