Research On Material Parameter Inversion Method Of Panel Rockfill Dam Based On SSA-MSVR

With the increasing maturity of construction technology,panel rockfill dams have gradually become the preferred dam type for dam construction under complex geological conditions due to the advantages of small engineering quantity,cost saving,strong adaptability to foundation and higher structural safety.At present,the filling height of panel rockfill dams has reached 200m,and the consequences of these high-panel rockfill dams are serious,and it is necessary to understand their true operational behavior,especially for dams that have been in service for many years.As an important index of dam structure analysis,the material parameters of dam body are mainly obtained through traditional indoor test,in-situ test and inversion analysis method.Indoor tests and in-situ tests are affected by sites,equipment,etc.,and it is difficult to accurately obtain material parameters,and a large number of studies have shown that with the increasing service time,the material parameters obtained through traditional tests will be very different from the actual situation.Compared with the traditional test,the parameters obtained by the inversion analysis can represent the most real operating behavior of the dam,and the material parameters obtained by the inversion can be used to calculate the dam structure and analyze the safety state of the dam.Based on the secondary development interface provided by MSC.Marc software,this paper writes the calculation subprograms of Duncan-Chang E-B model and Burgers rheological model of rockfill dam body materials,and proposes an adaptive parameter inversion method for rockfill dam based on sparrow search algorithm(SSA)and multi-output support vector regression(MSVR),which inverts the parameters of Duncan-Chang E-B model and Burgers rheological model,respectively,and finally uses the parameters obtained by inversion to predict the settlement value of rockfill dam.The main research contents of this paper are as follows:(1)According to the basic principles of Duncan-Chang E-B model and Burgers rheological model,using the HYPELA2 and CRPLAW secondary development interfaces provided by MSC.Marc,the subprograms of the E-B model and Burgers rheological model were written through the Fortran language to calculate the displacement and stress of rockfill dams.For a panel rockfill dam project,the displacement and stress of the dam body were calculated by using the E-B constitutive model and Burgers rheological model subprogram developed in this paper,and the rationality of the E-B model and Burgers rheological model calculation program obtained in this paper was verified by comparing the calculation results with other literature.(2)The basic principles of SSA and MSVR are introduced,and an intelligent inversion method for E-B model parameters of rockfill dam materials is proposed based on SSA and MSVR,and SSA is used to optimize the nuclear parameters par and penalty factor C of the MSVR model to realize the adaptability of the MSVR model and establish an MSVR-based agent model.At the same time,the sensitivity analysis of the E-B model parameters of rockfill dam was carried out by orthogonal test,and the parameter with high sensitivity was determined to be the parameter to be inverted.The training samples of the MSVR model are calculated by the finite element of the E-B constitutive model developed twice,and the surrogate model is trained by using the samples instead of the finite element calculation.Finally,aiming at the settlement value of the first completed water storage,SSA is used to perform inversion calculation on the determined inversion parameters to obtain the real E-B parameters of the rockfill dam.Engineering examples show that the parameter inversion method of the E-B model proposed in this paper has good inversion speed and inversion accuracy,and the parameters obtained by inversion can be used for finite element calculation.(3)Based on SSA and MSVR models,an inversion method for the parameters of Burgers rheological model of rockfill dam materials was proposed.According to the sensitivity analysis results,the parameters to be inverted by the Burgers rheological model of rockfill dams were determined.Using the finite element of the previously developed rockfill dam Burgers rheological model to calculate the 15-day settlement value of rockfill dam in the operation period from August 7,2006 to March 5,2007 after the initial completion of water storage in the reservoir(August 6,2004),the training samples of the MSVR model were established,and the fitting of the rheological settlement value of the rockfill dam was realized through the MSVR model,which was used instead of finite element calculation in the inversion calculation.Finally,the rheological parameters of the inversion are calculated by SSA,and the real rheological parameters of the rockfill dam are obtained.The E-B parameters and rheological parameters obtained by inversion are brought into the finite element calculation,and the E-B model and Burgers rheological model of the rockfill dam developed earlier are used to calculate the settlement value of the dam 1000～1650 days after the initial water storage,and the measured data of 1000～13 00 days are used to compare to verify the accuracy of the inversion parameters,and the settlement value after 1300 days is predicted,and the settlement prediction model of rockfill dam is established.