| When the sluice is built on the soft soil foundation,it may encounter problems such as uneven foundation settlement,foundation penetration and deformation,which may further lead to the sluice bottom plate emptying phenomenon and cause more serious disasters.Therefore,appropriate measures must be taken to prevent and solve these problems,so as to ensure the safe and stable operation of sluice.In recent years,a diagnostic method of sluice floor emptying based on structural dynamic characteristics has become increasingly popular.The dynamic characteristics adopted by this method are mostly modal parameters of the structure,but the parameter selection is single,and its sensitivity to sluice floor emptying needs to be improved.Therefore,the influence of different modal parameters and their derivatives on sluice floor emptying is explored.It is of great significance to determine more sensitive dynamic characteristics of sluice floor emptying.Based on the existing methods,this paper analyzes and compares the sensitivity of floor emptying with different modal parameters,and conducts emptying inversion research based on finite element model and indoor physical model.The specific contents are as follows:(1)Aiming at the problem that the current dynamic diagnosis method of the floor of soft foundation sluice has little research on the sensitive characteristic quantity,this paper will summarize and analyze the dynamic parameters mature in the field of damage identification,comprehensively compare the advantages and disadvantages of different modal parameters or their derivatives,and study the rule of their vibration response in sluice structure.Thus,a dynamic parameter,modal flexibility,which is more sensitive to structural damage and more feasible in the identification of sluice floor empties,is introduced.(2)In view of the lack of quantitative analysis of the emptying sensitivity of modal parameters in the existing diagnostic methods,this paper proposes a method of floor emptying sensitivity analysis of modal parameters of soft base sluice,determines the sensitivity index of modal parameters to floor emptying,constructs the calculation formula of the emptying sensitivity coefficient,and sets five emptying degrees.The sensitivity coefficients of the modal parameters of each order and each measuring point under different degrees of cavitation are calculated.The results show that the modal compliance is a more sensitive dynamic parameter than the frequency and mode shape.Based on the ranking of sensitivity coefficients,the weight coefficients of each subfunction of the objective function in subsequent inversion analysis were assigned.(3)The modal flexibility is taken as the sensitive characteristic quantity of sluice floor emptying dynamics,and the finite element model of sluice floor emptying is inverted,and the results of frequency mode shape method are compared and analyzed to verify the superiority of the modal flexibility method.Firstly,a mathematical model describing the floor emptying is established,and three typical working conditions are set up.The response surface model of different modal parameters and void parameters under different working conditions is established.The sensitivity analysis and calculation of the modal parameters of each order and each measurement point were carried out.Weights were assigned to different sub-objective functions based on the sensitivity level,and the objective functions of the void inversion with higher accuracy and stability were constructed.Based on genetic algorithm,the objective function is optimized and the emptying range of sluice bottom plate is inverted.The results show that the inversion accuracy of modal compliance method is higher.(4)In order to verify the feasibility of modal compliance method in practical engineering,indoor physical model tests will be carried out in this paper.Calculate the material parameters and EFS value of the physical model of the sluice under the current working condition,and revise the finite element model of the sluice again.The velocity response signals of the sluice structure are collected by vibration test and modal parameters are identified.The modal compliance values of each measuring point are calculated.Based on modal flexibility,the floor void range inversion of sluice physical model is carried out.The results show that the modal compliance method is feasible,reduces the relative error,improves the precision of inversion,and provides a new way for the diagnosis of soft foundation sluice floor void. |
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