Numerical Analysis Of Tunnel Damage And Stability Under Oil Tank Explosion

The dynamic response and damage of tunnels under the load of oil tank explosion is an important basis for engineering protection design and safety assessment.The development of dynamic numerical simulation method in line with the characteristics of oil tank explosion is of great significance to accurately analyze the stability of tunnel structures under the explosion of liquefied petroleum gas(LPG)tank.Firstly,the fluid computational mechanics software FLACS based on fluid correction method was used to calculate the explosion load of oil and gas in the tunnel.The feasibility of the method was verified by comparing the simulation results with the test data.Secondly,based on the calculated LPG blast load,transient dynamic analysis software LS-DYNA was used to apply the blast impact load to the tunnel lining surface,and then the dynamic response and damage of the lining structure under the blast load were calculated.The comparison between the simulated overpressure peak value and the results calculated by the empirical formula shows that the two results are in good agreement,indicating that the simulation method has good applicability for analyzing the stability of tunnel structure under LPG explosion in tunnel.Based on the numerical simulation results,the corresponding research work is carried out as follows:(1)The propagation characteristics of the blast wave are analyzed,including the reflection,diffraction and transmission of the blast wave,the propagation process of the blast wave,the location of the transition area from three-dimensional propagation to one-dimensional propagation and the judgment basis.At the same time,the “angular structure” of the tunnel has a strengthening effect on shock wave reflection,resulting in the formation of stress concentration in the corresponding position,and the stress wave intensity attenuation is slow.(2)In view of the characteristics of LPG explosion shock wave with long duration,low peak overpressure and large impulse,the transverse and longitudinal variation of shock wave intensity was studied.Based on the numerical simulation results,the empirical formula suitable for LPG explosion shock wave overpressure value was obtained,and the applicable conditions were given.(3)Transient dynamic analysis software LS-DYNA was used to simulate and analyze the dynamic response of tunnel lining structure under LPG explosion load,which mainly includes: the variation law of peak velocity,displacement and acceleration of the joints at special parts of the lining structure along the longitudinal and transverse direction of the tunnel,the attenuation law of peak velocity,displacement and acceleration of the joints at different sections,and the variation law of velocity,displacement and acceleration components of the joints at different sections in X,Y and Z directions.(4)The failure process of lining structure is analyzed by numerical simulation method,and the scope of complete failure area,serious failure area and slight failure area of lining structure is determined by using singledegree-of-freedom failure criterion.Under the action of explosion load,the lining structure in the area near the explosion center is most affected.The lining structure expands and deforms outward as a whole.The deformation of the lining top and bottom structure is large,which is more prone to internal structure damage,and the damage degree of the sidewall is small.In order to improve the explosion resistance of the tunnel structure,corresponding preventive measures should be taken for the vulnerable area.The research results have a certain reference value for the anti-explosion design and safety and stability analysis of the tunnel.