| The water-sealed underground petroleum storage caverns is the oil reserve mode which both international and national are in main development.Compared with the ground storage,it has the advantages such as smaller floor area,lower chronic cost,higher security,and suitable for combat readiness.Underground Water Sealed Caverns are underground engineerings which designed with high sidewall,longspan and did't use lining frequently.Because of the Underground Water Sealed Caverns' specific characteristics,the cavern can keep good oil storage performance only in a dynamic water seal environment.Although there are some successful examples abroad,for various reasons,our country hasn't mastered the core technology on the construction of cavern,and we are still in the exploratory stage.In order to fill the gaps on the construction of Underground Water Sealed Caverns in energy reserves and considering the particularity of the caverns,it has important engineering significance and strategic value to carry out the engineering geological practice and optimization design application research on Underground Water Sealed Caverns.The paper combines the project of the water-sealed underground petroleum storage caverns project proposed by the national petroleum reservation phase ? project,which the design capacity is 3 million m3.For the Underground Water Sealed Caverns special engineering properties,the engineering geology and hydrogeological survey have been systematically carried out in the cave area.There are a lot of engineering drilling,engineering geophysics,related in-situ tests and hydrogeological tests have been done on the spot.A lot of physical and mechanical tests of the indoor rock mass were implemented in the laboratory which acquainted the Caverns' engineering geological characteristics and hydrogeological characteristics:The library site areas' main rock mass for building are the middle Permian monzonitic granite,diorite and late cretaceous granite porphyry,it has four faults and nine crush zones.Existing an obvious lithologic contact zone,library site area mainly has four groups of dominant joint plane,maximum principal stress direction is for NW308 °;The groundwater types in the cave reservoir area are mainly loose rock type pore water and bedrock fissure water.The permeability coefficient of rock mass is generally 10-5?10-3m/d,and the permeability coefficient varies with depth in four forms.Based on the comprehensive judgment,the rock mass level in the base area is dominated by class ? and ?.Based on underground caverns geology conditions and hydrogeological conditions and space distribution characteristics of rock mass.In the way of stability of surrounding rockmass from underground cavern,it was studied that the spatial layout optimization of underground water seal cavern works by determining the nature(engineering geological analysis)and quantify(Block Theory and numerical analysis),including the horizontal layout,embedded depth,axis direction,section shape and spacing of caverns of the main chamber of the water seal cavern project.Finally,the spatial layout optimization scheme of the underground water seal cavern project is formed:On the basis of full analysis of caverns engineering geology and hydrogeological conditions,the roof elevation of the main caverns is-100m,the main axis line is NW3000,the cross-section of the straight wall is the circular arch and the cavern spacing is 1.5-2.0 times cavern span.The optimization scheme of water-sealed underground petroleum storage cavern engineering space determined by study,it can not only support the construction of the national petroleum reservation cavern project,has great significance for the construction and safe operation of the water-sealed underground petroleum storage cavern project.But also provide guidance and engineering reference for the design and construction of water-sealed underground(oil,gas)storage cavern project which is being implemented in China through its investigation and research methods. |
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