A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively...A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively tested by uniaxial test machine to obtain their stress—strain curves with hysteretic loops. The hysteretic loops do have two properties of P-M hysteretic systems： wiping out and congruency. It is proved that P-M model is applicable for the analysis of these two metals’ hysteresis. This model was applied on Mg at room temperature and Co at 300 ℃. By the P-M model, Co and Mg nonlinear elastic deformation can be calculated based on the stress history. The simulated stress—strain curves agree well with the experimental results. Therefore, the mechanical hysteresis of these two metals can be easily predicted by the classic P-M hysteretic model.展开更多
A simplified approach is presented for the analysis of the settlement of vertically loaded pile groups. In order to simulate the nonlinear pile-to-pile interaction in pile groups, the soils along the piles are assumed...A simplified approach is presented for the analysis of the settlement of vertically loaded pile groups. In order to simulate the nonlinear pile-to-pile interaction in pile groups, the soils along the piles are assumed to behave as a series of nonlinear springs subjected to the shaft shear stress at the pile/soil interface. Considering the displacement reduction induced by the pile-to-pile interaction, the shear-deformation method is adopted to approximate the displacement field of the layered soils around the piles, and the equivalent stiffness of the springs is obtained. Furthermore, the load-settlement response of pile groups is deduced by modifying the load-transfer functions to account for the pile-to-pile interaction. The settlements of a laboratory pile groups computed by the presented approach are in a good agreement with measured results. The analysis on Contrastive parameters shows that the settlements of pile group decrease with the increase of the pile space and pile length, and the part of piles exceeding the critical pile length has little contribution to the beating capacity of the pile groups.展开更多
Relative permeability is an indispensable property for characterizing the unsaturated flow and induced deformation in soils. The widely used Mualem model is inadequate for deformable soils because of its assumption of...Relative permeability is an indispensable property for characterizing the unsaturated flow and induced deformation in soils. The widely used Mualem model is inadequate for deformable soils because of its assumption of a rigid pore structure and the resultant unique dependence of the tortuosity factor on the volumetric water content. In this study, a unified relationship between the relative permeability and the effective degree of saturation was proposed for deformable soils by incorporating our newly developed water retention curve model into the original Mualem model, in which a new tortuosity factor was defined using the fractal dimension of flow paths and the mean radius of water-filled pores for representing the effect of pore structure variation. The modified deformation-dependent relative permeability model was verified using test data on five types of soils; the verification revealed a much better performance of the proposed model than the original model, which commonly overestimates the relative permeability of deformable soils. Finally, the proposed model was implemented in a coupled numerical model for examining the unsaturated flow and elastoplastic deformation processes in a soil slope induced by rain infiltration. The numerical results showed that the deformation-dependent nature of relative permeability has a remarkable effect on the elastoplastic deformation in the slope and that neglect of the deformation-dependent behavior of relative permeability causes overestimation of the depth of failure.展开更多
基金Projects (51002045, 10947105) supported by the National Natural Science Foundation of ChinaProject (2010B430016) supported by the Nature Science Research Project of Education Department of Henan Province, ChinaProject (2012IRTSTHN007) supported by Program for Innovative Research Team (in Science and Technology) in the University of Henan Province, China
文摘A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively tested by uniaxial test machine to obtain their stress—strain curves with hysteretic loops. The hysteretic loops do have two properties of P-M hysteretic systems： wiping out and congruency. It is proved that P-M model is applicable for the analysis of these two metals’ hysteresis. This model was applied on Mg at room temperature and Co at 300 ℃. By the P-M model, Co and Mg nonlinear elastic deformation can be calculated based on the stress history. The simulated stress—strain curves agree well with the experimental results. Therefore, the mechanical hysteresis of these two metals can be easily predicted by the classic P-M hysteretic model.
基金Project(50708033) supported by the National Natural Science Foundation of ChinaProjects(200923, CXKJSF0108-2) supported by Transportation Technical Project of Hunan Province, China
文摘A simplified approach is presented for the analysis of the settlement of vertically loaded pile groups. In order to simulate the nonlinear pile-to-pile interaction in pile groups, the soils along the piles are assumed to behave as a series of nonlinear springs subjected to the shaft shear stress at the pile/soil interface. Considering the displacement reduction induced by the pile-to-pile interaction, the shear-deformation method is adopted to approximate the displacement field of the layered soils around the piles, and the equivalent stiffness of the springs is obtained. Furthermore, the load-settlement response of pile groups is deduced by modifying the load-transfer functions to account for the pile-to-pile interaction. The settlements of a laboratory pile groups computed by the presented approach are in a good agreement with measured results. The analysis on Contrastive parameters shows that the settlements of pile group decrease with the increase of the pile space and pile length, and the part of piles exceeding the critical pile length has little contribution to the beating capacity of the pile groups.
基金supported by the CRSRI Open Research Program(Grant No.CKWV2015209/KY)the National Natural Science Foundation of China(Grant Nos.51409198,51179136&51222903)
文摘Relative permeability is an indispensable property for characterizing the unsaturated flow and induced deformation in soils. The widely used Mualem model is inadequate for deformable soils because of its assumption of a rigid pore structure and the resultant unique dependence of the tortuosity factor on the volumetric water content. In this study, a unified relationship between the relative permeability and the effective degree of saturation was proposed for deformable soils by incorporating our newly developed water retention curve model into the original Mualem model, in which a new tortuosity factor was defined using the fractal dimension of flow paths and the mean radius of water-filled pores for representing the effect of pore structure variation. The modified deformation-dependent relative permeability model was verified using test data on five types of soils; the verification revealed a much better performance of the proposed model than the original model, which commonly overestimates the relative permeability of deformable soils. Finally, the proposed model was implemented in a coupled numerical model for examining the unsaturated flow and elastoplastic deformation processes in a soil slope induced by rain infiltration. The numerical results showed that the deformation-dependent nature of relative permeability has a remarkable effect on the elastoplastic deformation in the slope and that neglect of the deformation-dependent behavior of relative permeability causes overestimation of the depth of failure.
