DESIGN AND CONSTRUCTION ASPECTS OF UNLINED OIL STORAGE CAVERNS IN ROCK

An, underground oil storage facility comprising sit storage caverns is under construction in southern Korea. Each of the horseshoe-shaped ca verns is 18 m wide, 30 m high, and 400-600 m long. The artificial wate r curtain system used consisted of water curtain tunnels and horizonta l boreholes drilled from these tunnels, and pre-grouting measures have been introduced to keep the bedrock saturated all the time in, order prevent oil from migrating through rock mass. The results of site inve stigation show that the bedrock at the site was very competent and imp ermeable and, hence, a suitable medium for the storage of oil. This co nclusion was confirmed later by the results of design analysis, the re vised instrumentation program, and hydraulic tests performed during co nstruction. In general, design concepts for the excavation and support and water curtain system have been verified to be reasonably good in, terms of the technical soundness and economy. The results of the revi sed instrumentation program indicate that the three-dimensional excava tion behaviour is complex and should be studied in more detail.