Research And Application Of Key Technologies For Construction Of Large Underground Reserve Caverns Under Complex Geological Conditions

At present,the contradiction between oil supply and demand at home and abroad is increasingly prominent,and the oil crisis facing China will also become more and more serious.According to statistics,China accounts for only 18.3% of the world’s per capita oil resources,while China’s oil consumption accounts for 7% of the world,second only to the united States.With the rapid development of China’s economy,the demand for oil is also increasing rapidly.During the "Thirteenth Five-Year Plan" period,China’s dependence on foreign oil has exceeded 60%.In addition,as a strategic resource,oil resources must be stored in large quantities.Therefore,in order to strengthen domestic oil security and respond to emergencies,China officially launched the establishment of an underground oil reserve system in 2003.Faced with the urgency of the current national oil reserves,it is not enough to rely solely on the experience and technical strength of similar domestic projects.Although we can learn from some mature foreign experience,we cannot directly use foreign experience and technology due to restrictions on foreign technology protection.Therefore,when China is building large-scale underground oil storage caverns.In close connection with an underground oil storage project in southern China.It is of great practical significance to carry out " research on key technologies for construction of large underground reserve tunnels under complex geological conditions".Through engineering analogy,theoretical analysis and numerical simulation,the following main results have been achieved:(1)Construction Technology of Large Span Flat DomeThe storage cavern dome is a spherical large-span horizontal organization.During the construction process,the excavated section is always in a state of dynamic change.Linear control is difficult.In order to ensure the stability and appearance of dome surrounding rock.For the first time,a top-lifting ring construction method is proposed and applied.The construction practice shows that the method is beneficial to control the deformation of surrounding rock and the profile of excavation section of cavern,has high construction efficiency,reduces the construction cost and achieves the expected effect of design.(2)Construction Technology of Tank ShaftShaft is the main channel for mucking and ventilation in construction,and its rapid through formation is of great significance for speeding up the construction progress and improving the construction environment.In order to achieve the above goals,a shaft construction scheme combining " inverted bell mouth" and " normal bell mouth" is proposed and applied for the first time.The engineering practice shows that the method has the advantages of simple process,high construction efficiency and small potential safety hazard,is convenient for on-site organization,and achieves the expected effect.(3)Tank body expanding excavation technologyPart of the tank body to be excavated has a large amount of work,and the amount of blasting slag is about 7000 m,which is the key part affecting the construction period of the reserve cavern.In order to speed up the construction progress,the " spiral" expansion excavation construction method is proposed for the first time.Engineering practice shows that the method can organize excavation and support parallel operations,with high degree of mechanized construction,high construction efficiency and obvious benefits,and achieves the expected purpose.(4)Section detection technologyThe storage cavern is a combination of spherical crown dome and cylindrical tank.The dynamic change of profile section puts forward high requirements for the formation of blasting construction section.In order to detect the construction section quickly and accurately,the section detection technology based on " total station method" is proposed and applied for the first time.That is,the spherical radius of the dome and the circular radius of the tank cross section are obtained by using solid geometry kNowledge,the coordinates of the excavation profile are obtained by total station measurement,and the construction radius is obtained by data processing.The construction effect is rapidly evaluated by comparing the two.Engineering practice shows that this method can quickly and accurately evaluate overbreak and underbreak,which is of great significance for controlling the cross-section shape and improving the cross-section forming effect.(5)Secondary lining construction technology of cavernThe secondary lining of the cavern adopts an integral wall-attached reinforced concrete structure.The secondary lining of dome is of variable cross-section structure and requires one-time casting.The template for secondary lining concrete construction adopts 3012 standard steel template and isosceles trapezoid wood board with a thickNess of 5cm to assemble the template.Ⅰ 14 I-steel radial arch,Φ 48 steel pipe(wall thickNess 3.5mm)hoop arch and bowl-type scaffolding and scaffolding as the support system of the template system;The construction sequence of the tank body before the dome is adopted,which is divided into five molds from bottom to top for pouring construction.I.e.tank body 3 mould,ring beam 1mould and dome 1 mould.Engineering practice shows that.The support system of this method is stable,the concrete strength and appearance quality meet the design requirements,the economic benefit is obvious,and the expected design effect is achieved.