Investigation On Pressure Resistance And Safety Of Cover Soil Spherical Tank

Spherical tanks are widely used in the chemical industry due to their own storage advantages,and with the rapid development of the chemical industry and the continuous improvement of advanced machinery manufacturing technology,the large-scale and highparameterization of spherical tanks have become the main development trend at present.However,the existing above-ground spherical tanks will continue to react with the combustibles outside the tank to form a combustible vapor cloud and explode if they leak or explode under severe environments such as high pressure and corrosion.The explosion shock wave will even drive debris to cause nearby storage tanks to occur.Perforation or plastic failure,forming a domino effect.If the spherical tank is covered with soil,the above problems can be solved well.In addition,the above-ground space can be saved after the spherical tank is covered with soil,which is also of great significance to the current shortage of urban land and the need for strategic reserves.However,when the spherical tank is covered with soil,it also brings other problems.Firstly,whether the soil pressure above the spherical tank causes the buckling failure of the spherical shell,and the risk assessment of the spherical tank in the soil-covering mode.Therefore,the investigation on the pressure resistance and safety of cover soil spherical tank has important theoretical and engineering significance.The thesis starts with the soil pressure distribution of the cover soil spherical tank.Through the analysis of the existing soil pressure calculation methods,a two-dimensional plane numerical simulation method is used to propose a maximum soil pressure calculation method that is more in line with the actual situation.Combining the numerical simulation of the soil pressure distribution and the classical experimental results of the buried horizontal tank by Shmulevich et al.,the radial and tangential soil pressure components acting on the top of the spherical tank are deduced,and the experiments of the cover soil spherical tank are used to carry out validation analysis.Then,the stability of the cover soil spherical tank under soil pressure and other loads is studied.Due to the uneven distribution of the earth pressure load,the eigenvalue buckling analysis method is selected for buckling calculation.Taking an Φ12368×34mm spherical tank as the research object,the finite element model was established through a series of steps of element selection,model establishment,and mesh convergence analysis.The correctness of the finite element model was verified by the membrane theory solution.Through the analysis of the buckling characteristic value of the spherical tank under the most unfavorable pressure,the critical buried depth is 38.4m when the spherical tank is unstable,and the test verification analysis of the spherical tank reduction model is carried out.Finally,the hazard source analysis of the cover soil spherical tank filled with liquefied petroleum gas was carried out,and the four types of explosions were clarified.Moreover,the accident tree was used to conduct a qualitative analysis with the " cover soil spherical tank explosion" as the top event,and the downward method was used to derive Draw out the minimum cut set and sort the importance of the basic events,and determine the possibility of fire and explosion caused by the residual substance in the tank and the knock on the tank body.At the same time,it is determined that the explosion process of the cover soil spherical tank in the soil is a near-surface explosion.The relationship is obtained by the TNT equivalent method and the Lakehoff empirical formula between the shock wave overpressure,vibration velocity and distance.A comparative analysis of the impact radius of an explosion on the same scale on the ground shows that the storage safety of the overburden is higher.