The generalized plasticity constitutive equations that simulate, in a unified manner, the stress-strain response and the creep behavior of rockfill materials are derived using the concept of elastoplasticity. A single...The generalized plasticity constitutive equations that simulate, in a unified manner, the stress-strain response and the creep behavior of rockfill materials are derived using the concept of elastoplasticity. A single yield surface is assumed to capture the onset of plastic strains with, however, two separate potential functions for the stress-induced plastic strains and the creep strains,respectively. The involved tensors and scalars are then specified directly, following the generalized plasticity method, to substantiate the constitutive equations. The model thus obtained is verified using triaxial compression experiments, true triaxial experiments and triaxial creep experiments. The effectiveness of the model is also demonstrated by a successful application in studying the behavior of a high concrete face rockfill dam(CFRD). It is found that for a high CFRD with a long construction period, neglecting the creep of rockfill materials during construction results in an underestimation of the deformation of the dam.The deformation and stress of the concrete slabs may also be considerably underestimated.展开更多
Soil undergoes both elastic and plastic deformations under different loading conditions. A relatively accurate constitutive model of soil behaviors should be capable of predicting the elastic and plastic deformations ...Soil undergoes both elastic and plastic deformations under different loading conditions. A relatively accurate constitutive model of soil behaviors should be capable of predicting the elastic and plastic deformations properly. Among a large number of elastoplastic constitutive models developed over the last several decades, constitutive models based on generalized plasticity have been successfully utilized in modeling the mechanical behavior of various soils. This paper attempts to present a review of the most recent developments of generalized plasticity models for geotechnical problems. After a brief review of generalized plasticity theories and constitutive models, limitations of the original Pastor-Zienkiewicz model in practical application are summarized. Afterwards, recent achievements in the generalized plasticity models for both saturated and unsaturated soils and their applicability are analyzed, and a general approach for modification of generalized plasticity models is highlighted.展开更多
In this paper, two different concepts for the constitutive modeling of the mechanical behavior of creep-sensitive rockfill materials are presented. Specifically, the performance of an extended generalized plasticity m...In this paper, two different concepts for the constitutive modeling of the mechanical behavior of creep-sensitive rockfill materials are presented. Specifically, the performance of an extended generalized plasticity model proposed by Wang is compared with a simplified version of the hypoplastic constitutive model for weathered rockfill materials proposed by Bauer. Both models can reflect the influence of the mean stress on the incremental stiffness, the peak friction angle, and the dilatancy angle. The so-called solid hardness defined for a continuum description and originally introduced by Bauer is embedded in both models. Hydrochemical, thermal, and mechanical weathering are usually caused by environmental changes and are taken into account in a phenomenological description with an irreversible and time-dependent degradation of the solid hardness. A degradation of the solid hardness is usually accompanied by creep deformation of the stressed rockfill material. It is shown that appropriate modeling of creep deformation requires at least a unified description of the interaction between the time-dependent process of degradation of the solid hardness and the stress state. In this context, the solid hardness can be understood as a key parameter for describing the evolution of the state of weathering of the rockfill material. Particular attention is also paid to the necessary procedure for determining the constitutive constants of the two different constitutive models. Finally, the performance of the two different constitutive models is demonstrated by comparing the results obtained from numerical simulations with experimental data from the creep-sensitive rockfill material.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0404806)the National Natural Science Foundation of China(Grant Nos.51779152,51539006)
文摘The generalized plasticity constitutive equations that simulate, in a unified manner, the stress-strain response and the creep behavior of rockfill materials are derived using the concept of elastoplasticity. A single yield surface is assumed to capture the onset of plastic strains with, however, two separate potential functions for the stress-induced plastic strains and the creep strains,respectively. The involved tensors and scalars are then specified directly, following the generalized plasticity method, to substantiate the constitutive equations. The model thus obtained is verified using triaxial compression experiments, true triaxial experiments and triaxial creep experiments. The effectiveness of the model is also demonstrated by a successful application in studying the behavior of a high concrete face rockfill dam(CFRD). It is found that for a high CFRD with a long construction period, neglecting the creep of rockfill materials during construction results in an underestimation of the deformation of the dam.The deformation and stress of the concrete slabs may also be considerably underestimated.
基金supported by the Central Public Welfare Fund of China (Grant No.Y710005)the China Scholarship Council (CSC)
文摘Soil undergoes both elastic and plastic deformations under different loading conditions. A relatively accurate constitutive model of soil behaviors should be capable of predicting the elastic and plastic deformations properly. Among a large number of elastoplastic constitutive models developed over the last several decades, constitutive models based on generalized plasticity have been successfully utilized in modeling the mechanical behavior of various soils. This paper attempts to present a review of the most recent developments of generalized plasticity models for geotechnical problems. After a brief review of generalized plasticity theories and constitutive models, limitations of the original Pastor-Zienkiewicz model in practical application are summarized. Afterwards, recent achievements in the generalized plasticity models for both saturated and unsaturated soils and their applicability are analyzed, and a general approach for modification of generalized plasticity models is highlighted.
基金supported by the CRSRI Open Research Program(Grant No.CKWV2016375/KY)the National Natural Science Foundation of China(Grants No.51609182,51379130,and 51209141)the Chinese Scholarship Council
文摘In this paper, two different concepts for the constitutive modeling of the mechanical behavior of creep-sensitive rockfill materials are presented. Specifically, the performance of an extended generalized plasticity model proposed by Wang is compared with a simplified version of the hypoplastic constitutive model for weathered rockfill materials proposed by Bauer. Both models can reflect the influence of the mean stress on the incremental stiffness, the peak friction angle, and the dilatancy angle. The so-called solid hardness defined for a continuum description and originally introduced by Bauer is embedded in both models. Hydrochemical, thermal, and mechanical weathering are usually caused by environmental changes and are taken into account in a phenomenological description with an irreversible and time-dependent degradation of the solid hardness. A degradation of the solid hardness is usually accompanied by creep deformation of the stressed rockfill material. It is shown that appropriate modeling of creep deformation requires at least a unified description of the interaction between the time-dependent process of degradation of the solid hardness and the stress state. In this context, the solid hardness can be understood as a key parameter for describing the evolution of the state of weathering of the rockfill material. Particular attention is also paid to the necessary procedure for determining the constitutive constants of the two different constitutive models. Finally, the performance of the two different constitutive models is demonstrated by comparing the results obtained from numerical simulations with experimental data from the creep-sensitive rockfill material.
