Research And Application On High-performance Shotcrete Used For Large Underground Water Seal Oil Carve Storage

Sprayed concrete in the underground engineering construction embodies the superiority of more, as the materials, equipment and construction technology improvement, sprayed concrete become an indispensable modern underground engineering construction materials.As the underground water seal oil depot significantly increased demand of large-scale construction, also is bound to promote the wide application of sprayed concrete construction technology and rapid development.For underground oil storage caves in Shandong for this particular project, sprayed concrete in its whole structure is not as before most of the underground engineering supporting,"temporary" adopted by the outside of the shotcrete layer without lining layer for protection, but the shotcrete layer as the innermost structure of underground structure (direct contact with crude oil), become a permanent structure layer is used.Therefore, for underground water seal oil underground structure with sprayed concrete, in addition to the strength of the guarantee, also need to ensure that its bond strength with rock, control of sprayed concrete permeability, make the shotcrete "infiltration and not leak" unique performance, improve its performance in terms of the whole structure of waterproof impermeability, to ensure that the runtime reduce workload of osmotic quantity and oil-water separation, water reduces the operating costs at a later stage of oil depot.In this paper, through theoretical analysis and field test and numerical calculation methods, the research on performance guarantee sprayed concrete, the basic physical and mechanical properties such as compressive strength under the premise of efforts to improve its permeability resistance and bond strength, reduce the shrinkage of sprayed concrete, as a whole to improve the long-term durability of the sprayed concrete, for underground water seal oil depot of sprayed concrete service provide a reliable guarantee for a long time.This study can provide the similar engineering of the theory basis for dynamic design and site construction, provide guidance for oil depot operating costs and long-term service, has very important scientific research value and social significance.This article main research conclusion is as follows:(1) The design of mixture ratio.Underground water seal oil underground structure with shotcrete for the permanent protection layer, therefore, when the mixture ratio design need to pay special attention to the type and quality of raw materials and the quality of aggregate and grading, water/cement ratio, the change of the accelerator and the adaptability of gelled material parameters.For adding mineral admixtures of sprayed concrete, should not be mixed with fly ash, appropriate chooses silicon powder and slag as supplementary cementing materials, and content need to be in accordance with the requirements of practical engineering and testing to determine in the end.(2) The workability of sprayed concrete.Mineral admixtures can affect the setting time of mixing accelerator cement materials, different admixtures and setting time of cement materials, the influence of slag and fly ash were increased gel system of setting time, and the setting time of silicon powder to shorten gelation system.Basic performance is:the dosage of slag in less than40%when the initial setting time of the gel system is affected, both within6min, the initial setting and final setting time, but the final setting time basic is less than15min.(3) The basic mechanical properties of sprayed concrete.Mixing concrete early strength of fly ash and slag is slightly lower than the benchmark concrete, but the late strength is higher, silicon powder can increase the concrete age strength.Engineering application showed that adding30%slag after28d compressive strength of shotcrete is still in the above40mpa.Slag and fly ash on the concrete bonding performance is affected, silicon powder is helpful to the improvement of the performance of the concrete bonding, and bonding properties have a certain relationship with its strength and working performance.(4) Durability performance of sprayed concrete.Mineral admixtures can improve the permeability resistance of concrete, the silicon powder for best performance.But silicon powder increased the drying shrinkage of concrete, and the slag and fly ash can reduce the drying shrinkage of concrete, suggested that the doped silicon powder concrete early maihtenance.In addition, the SRA can effectively reduce dry shrinkage of concrete, reduce their risk of cracking.Mineral admixtures can effectively reduce the oil permeability in concrete;In concrete are soaked with oil, do not affect the overall performance. Slag to a certain extent reduce the shotcrete stable water quantity and water absorption coefficient, improve the permeability resistance of sprayed concrete. (5) The microstructure evolution of sprayed concrete performance related.Slag and silica fume can improve the hydration degree of cement gelled material, dosage, the greater the increase, the more obvious, but it will consume a certain amount of Ca (OH)2. In addition, the mineral admixtures can improve the pore structure of concrete, improve the compactness and permeability resistance of concrete. Slag and silicon powder can effectively dense concrete microstructure, the SRA will not affect the crystal growth of concrete products, silicon powder, its activity is higher, cannot effectively consumption Ca (OH)2crystal.(6) The function of Sprayed concrete as the role of underground water seal oil underground structure water seal.Shotcrete layer as the first protective layer, underground water seal oil underground structure direct contact with oil, can reduce the infiltration of water through the water curtain to improve its permeability, reduce the operating cost in the underground structure run late; Mineral slag of high-performance shotcrete has a prominent role in the permeability resistance, can be used in underground water seal oil underground structure of water seal auxiliary protective layer.(7) Sprayed concrete problems existing in the application as the permanent works.Although sprayed concrete technology has been developed for a long time, also gradually mature, but as there are still some in the permanent works need to be further solve the problem:①The durability problem of sprayed concrete. The traditional shotcrete as a temporary support engineering, usually paid little attention to the durability, and shotcrete as permanent structure layer, the problems need attention, such as shotcrete infiltration resistance, frost resistance, resistance to sulfate of corrosive medium, such as corrosion, etc.;②The adhesive of the shotcrete and rock properties characterization. Bonding performance of shotcrete and rock experiment has been the basic mechanical properties of sprayed concrete in a difficulty, need to study more convenient, reliable, and close to the real value of the bond strength test method.