Study Of Cracking Mechanism And Prevention Measures Of Large LNG Storage Tank Concrete

Because of the rapid development of chinese economy and the high international oil prices,natural gas as a kind of clean energy with high calorific value is gradually being taken seriously.Developing natural gas industry has become the best choice for every nation in the world,in order to improve the environment and to maintain sustainable economic development.Large LNG storage tanks as the most economical and the most commonly used way of storing liquefied natural gas,its construction is in a stage of rapid growth in China.But now,China is still not independent design and construction,therefore,the study of Large LNG storage tanks is significant.External wall of LNG storage tank is mainly built by the prestressed concrete,the distribution of the stress and deformation is complex.In this thesis,I take the actual project as the object of study,and by theoretical calculation and comparative analysis of numerical results,the main job is as follows:1.First,in order to explore the mechanism of cracking during concrete outer tank,Various parameters were determined thermal analysis and structural analysis required.Through numerical simulation analysis process of pouring concrete outer tank ten layers,In the study of stress distribution in the tank after tank temperature,Summarized the concrete cracking prevention measures during construction.LNG storage tanks normally calculated using the forces inside the tank leaks case.2.External tank insulation and temperature stress calculation methods were introduced,And the actual project for the study,Using ANSYS software,In the study of stress distribution in the tank outside the tank,after the destruction of shape,Its summarized and presented on the basis of two kinds of outer tank structure optimization methods.The results showed that: During the construction of concrete outer tank,the lower the upper concrete influence depth of 1.8.The first layer relative to other layers pouring easier to crack first appeared outside of the bottom of the first crack is pouring layers.Facades under normal use,the large external tank force is reasonable.Design way of the external walls,Structural optimization methods.Medial and lateral cracks are not serious,but the inside of the concrete outer tank outside of the concrete greater than the chance of cracking.Including full tank leakage state,that the role of the ordinary and hydraulic load,the inside concrete outer tank and the outer concrete cracking have different positions,cracks are vertical cracks.Probability and the inside of the cracks larger than the outer.By analyzing the case of large LNG storage tanks facades bear loads and stress distribution,Gives the ring to adjust the prestressing steel,the tank wall thickness ranging from two structural design optimization design;Then according to each structure optimization program,established in ANSYS numerical model,the calculated results were analyzed separately,the results showed that the two kinds of programs have increased the carrying capacity of the tank.