Evaluation of the cyclic shear modulus of soils is a crucial but challenging task for many geotechnical earthquake engineering and soil dynamic issues. Improper determination of this property unnecessarily drives up d...Evaluation of the cyclic shear modulus of soils is a crucial but challenging task for many geotechnical earthquake engineering and soil dynamic issues. Improper determination of this property unnecessarily drives up design and maintenance costs or even leads to the construction of unsafe structures. Due to the complexities involved in the direct measurement, empirical curves for estimating the cyclic shear modulus have been commonly adopted in practice for simplicity and economical considerations. However, a systematic and robust approach for formulating a reliable model and empirical curve for cyclic shear modulus prediction for clayey soils is still lacking. In this study, the Bayesian model class selection approach is utilized to identify the most significant soil parameters affecting the normalized cyclic shear modulus and a reliable predictive model for normally to moderately over-consolidated clays is proposed. Results show that the predictability and reliability of the proposed model out performs the well-known empirical models. Finally, a new design chart is established for practical usage.展开更多
The unified hardening(UH)model proposed by Yao et al.(Geotechnique 2009)is the constitutive model which can consider the influence of the complex stress path and stress history on the deformation and strength of clays...The unified hardening(UH)model proposed by Yao et al.(Geotechnique 2009)is the constitutive model which can consider the influence of the complex stress path and stress history on the deformation and strength of clays reasonably.Firstly,the loading-unloading criterion of material model is defined as the change law of the intersection of current yield surface and the p axis,which makes the loading-unloading in the process of hardening and softening can be unified considered in UH model.Then,the Newton-Raphson method is adopted to attain the nonlinear problems solution in the finite element method of UH model,and the semi-implicit return mapping method is adopted to update stress.The application of the UH model in the finite element is realized.And then,the analyses of triaxial test are performed using the unit prediction and finite element method.The results of the unit prediction method are compared with the experimental results to illustrate the rationality of the UH model.Comparing the results with the unit prediction method and the finite element method,the correctness of the finite element program of the UH model is iUusttated.Further,Ae three-dimensional firdte element andysis of embankment on soft soil is performed by the program.The comparison between the results calculated by the UH model and the modified Cam-clay(MCC)model and the experimental data shows that the UH model is rational in analyzing the actual embankment engineering on soft soil.展开更多
In this paper,the thermodynamic behavior of soil was observed in well-known heating tests via a simulation,which included THMcoupled finite element analysis as the boundary value problem(BVP).The primary purpose of th...In this paper,the thermodynamic behavior of soil was observed in well-known heating tests via a simulation,which included THMcoupled finite element analysis as the boundary value problem(BVP).The primary purpose of the paper was to identify the necessity to model a phenomenon called‘the volumetric contraction of soft clay due to heating’by introducing some extra parameters in the thermoelastoplastic model in which the THM analyses were conducted.Based on the simulation,it was determined that the heating test is only a BVP,and the phenomenon is simply an average behavior of the BVP,not an inherent property of soil.Based on the universal rule that any material will expand when heated,it is not necessary to introduce an extra parameter into a properly organized thermo-elastoplastic model to describe the phenomenon.The results may provide a useful insight for researchers who are interested in modeling the thermodynamic behavior of soils.展开更多
基金Research Committee of the University of Macao under Grant No.MYRG2015-00048-FST
文摘Evaluation of the cyclic shear modulus of soils is a crucial but challenging task for many geotechnical earthquake engineering and soil dynamic issues. Improper determination of this property unnecessarily drives up design and maintenance costs or even leads to the construction of unsafe structures. Due to the complexities involved in the direct measurement, empirical curves for estimating the cyclic shear modulus have been commonly adopted in practice for simplicity and economical considerations. However, a systematic and robust approach for formulating a reliable model and empirical curve for cyclic shear modulus prediction for clayey soils is still lacking. In this study, the Bayesian model class selection approach is utilized to identify the most significant soil parameters affecting the normalized cyclic shear modulus and a reliable predictive model for normally to moderately over-consolidated clays is proposed. Results show that the predictability and reliability of the proposed model out performs the well-known empirical models. Finally, a new design chart is established for practical usage.
基金supported by the National Natural Science Foundation of China(Grants 11672015,51808547,and 51808548)the Central University Basic Scientific Research Business Expenses Funded Project(Grant 3122014C014)+1 种基金the Civil Aviation University Airport Engineering Base Open Fund(Grant JCGC2019KFJJ003)Tianjin Municipal Education Commission Scientific Research Project(Grant 2019KJ124)。
文摘The unified hardening(UH)model proposed by Yao et al.(Geotechnique 2009)is the constitutive model which can consider the influence of the complex stress path and stress history on the deformation and strength of clays reasonably.Firstly,the loading-unloading criterion of material model is defined as the change law of the intersection of current yield surface and the p axis,which makes the loading-unloading in the process of hardening and softening can be unified considered in UH model.Then,the Newton-Raphson method is adopted to attain the nonlinear problems solution in the finite element method of UH model,and the semi-implicit return mapping method is adopted to update stress.The application of the UH model in the finite element is realized.And then,the analyses of triaxial test are performed using the unit prediction and finite element method.The results of the unit prediction method are compared with the experimental results to illustrate the rationality of the UH model.Comparing the results with the unit prediction method and the finite element method,the correctness of the finite element program of the UH model is iUusttated.Further,Ae three-dimensional firdte element andysis of embankment on soft soil is performed by the program.The comparison between the results calculated by the UH model and the modified Cam-clay(MCC)model and the experimental data shows that the UH model is rational in analyzing the actual embankment engineering on soft soil.
文摘In this paper,the thermodynamic behavior of soil was observed in well-known heating tests via a simulation,which included THMcoupled finite element analysis as the boundary value problem(BVP).The primary purpose of the paper was to identify the necessity to model a phenomenon called‘the volumetric contraction of soft clay due to heating’by introducing some extra parameters in the thermoelastoplastic model in which the THM analyses were conducted.Based on the simulation,it was determined that the heating test is only a BVP,and the phenomenon is simply an average behavior of the BVP,not an inherent property of soil.Based on the universal rule that any material will expand when heated,it is not necessary to introduce an extra parameter into a properly organized thermo-elastoplastic model to describe the phenomenon.The results may provide a useful insight for researchers who are interested in modeling the thermodynamic behavior of soils.
