Pressure-impulse Theory Of Damage And Failure Caused By Blast Wave And Domino Effect Pre-control In Chemical Industry Parks

The centralized development of chemical industry parks not only brings industrial scale benefits,but also makes the distribution of large chemical plants and major hazard sources increasingly dense and highly concentrated.The instantaneous damage intensity of explosions is large and the influence range is wide.The blast wave can impose severe damage to adjacent devices,leading to the domino effect.In recent years,major and especially serious explosion accidents in domestic chemical industry parks have occurred from time to time,which fully shows the possibility and danger of domino effect induced by blast wave.Therefore,research on damage and failure theory caused by blast wave and domino effect pre-control in chemical industry parks has important practical significance and engineering application for improving the ability of safety and emergency management and the technical level of accident pre-control.At present,research on dynamic response of equipment failure caused by blast wave in chemical industry parks is abundant.However,there is a lack of theoretical models to quantitatively characterize the dynamic response of equipment failure,which leads to the simplification of the existing calculation methods of failure probability caused by blast wave.The calculation methods ignore the instantaneous characteristics of blast loads,structural and material characteristics of equipment and dynamic characteristics of failure process.At the same time,the research on pre-control of domino effect accidents induced by blast wave mainly focuses on the layout optimization based on safe distance.There is a lack of systematic precontrol strategy research.Therefore,with the explosion accident scenarios as the research object,the pressure-impulse(P-I)theory of damage and failure caused by blast wave as the core and the pre-control of domino effect accidents induced by blast wave as the purpose,the following studies are mainly carried out.(i)P-I damage mechanism of blast wave and equipment damage mechanism with multiple failure modes.The response mechanism of P-I damage caused by blast wave is analyzed.The general process of quantitative characterization for P-I damage is proposed.Three failure modes of atmospheric vertical storage tanks under blast wave are determined.The causes of multiple failure modes are analyzed.the nature of equipment failure with multiple failure modes is clarified.(ii)Dynamic response law and P-I theoretical models of displacement failure and overturning failure of storage tanks induced by blast wave.The dynamic response law of displacement failure and overturning failure of atmospheric vertical storage tanks is analyzed and the critical motion state of storage tanks is determined.Based on momentum conservation law and angular momentum conservation law,P-I theoretical models of displacement failure and overturning failure of atmospheric vertical storage tanks induced by blast wave are established,respectively,which achieve quantitative characterization between failure degree(maximum displacement distance,maximum rotation angle)and P,I.The models overcome the oversimplified limitation that Probit model only uses overpressure to represent failure degree.The models are verified by LS-DYNA simulations.The failure criteria and limit state equations(LSEs)of displacement failure and overturning failure are built to provide model basis for the calculation method of failure probability.(iii)Study on dynamic response law of buckling failure of storage tanks induced by blast wave.The buckling failure experiment of small scaled atmospheric vertical storage tanks under blast wave is carried out.The dynamic process of buckling deformation and the full-sized morphology data are analyzed.The influence of tank type,liquid type and liquid height on buckling deformation is studied.The finite element model of buckling failure of large scaled atmospheric vertical storage tanks under blast loads is established.The finite element modeling method is verified by experimental data.The buckling failure law,the influence of blast load parameters and storage tank parameters are studied.The relationship between buckling failure degree and stress,the applicable conditions for simplifying blast load parameters and the influence mechanism of liquids on the impact resistance of storage tanks are obtained,which provided the basis for the P-I theoretical model research of buckling failure.(iv)P-I theoretical model of buckling failure of storage tanks induced by blast wave.Based on the Donnell cylindrical shell theory,the P-I theoretical model of buckling failure of atmospheric vertical storage tanks caused by blast wave is established.The quantitative characterization between failure degree(maximum Von Mises stress)and P,I is realized,which overcomes the oversimplified limitation that Probit model only uses overpressure to represent failure degree.Distributed transfer function method is adopted to solve a set of ternary secondorder linear partial differential motion equations in the P-I theoretical model.Simulation results of buckling failure in Chapter 4 verify the model.A new P-I type – ‘sum of squares’ model is built,which can realize fast calculation and accurate judgment of buckling failure.The failure criterion and limit state equation of buckling failure are established to provide model basis for the calculation method of failure probability.(v)Calculation method of failure probability with multiple failure modes caused by blast wave and vulnerability analysis.The LSE surfaces or curves of the three failure modes are constructed to clarify the logical relationship among failure modes and the possible damage forms.The logical relationship is represented by directed graph of Bayesian network(BN)and the calculation method of failure probability with multiple failure modes based on BN is established.Monte Carlo method is used to verify the calculation method.The method solves the problem of overestimating the failure probability by assuming that the failure modes are independent of each other or only considering the relationship between partial failure modes.The critical equivalent TNT mass and critical stand-off distance are determined through vulnerability analysis and the key parameters are identified through sensitivity analysis of blast intensity parameters and tank parameters.The study provides probabilistic method support and pre-control technical support for dynamic probability assessment and pre-control of domino effect accidents.(vi)Dynamic probability assessment model for domino effect accidents induced by blast wave and ‘six-level’ pre-control strategies.Based on evolutionary process of domino effect accidents induced by blast wave,dynamic probability assessment model for domino effect accidents induced by blast wave is set up,which can realize the calculation of all orders of domino effect probabilities and all domino effect link probabilities.The master level of domino effect and the most likely domino effect link under different leak time can be determined.The most dangerous initial equipment unit and the most critical intermediate equipment unit can be identified.Based on disaster mitigation theory of broken chain,the ‘sixlevel’ pre-control strategies for evolutionary process of domino effect accidents induced by blast wave are constructed.The corresponding quantitative models of pre-control effects are established to compare and analyze the effectiveness of pre-control strategies at different levels.