Thermodynamic model of creep at constant stress and constant strain rate

Abstract A thermodynamic model has been developed that describes the entire creep process, including primary, secondary, and tertiary creep, and failure for both constant stress (CS) tests ( σ = const. ) and constant strain rate (CSR) tests ( ϵ = const. ), in the form of a unified constitutive equation and unified failure criteria. Deformation and failure are considered as a single thermoactivated process in which the dominant role belongs to the change of entropy. Failure occurs when the entropy change is zero. At that moment, the strain rates in CS tests reach the minima and stress in CSR tests reaches the maximum (peak) values. Families of creep (ϵ vs t) and stress-strain (σ vs ϵ) curves, obtained from uniaxial compression CS and CSR tests of frozen soil, respectively (both presented in dimensionless coordinates), are plotted as straight lines and are superposed, confirming the unity of the deformation and failure process and the validity of the model. A method is developed for determining the parameters of the model, so that creep deformation and the stress-strain relationship of ductile materials such as soils can be predicted based upon information obtained from either type of test.

[1]  L. K. Walker.  Stress Effect on Creep Rates of a Frozen Clay Soil , 1967 .

[2]  David M. Cole,et al.  Stress/strain/time relations for ice under uniaxial compression , 1983 .

[3]  Anatoly M. Fish.  Comparison of U.S.S.R. Codes and U.S. Army Manual for design of foundations on permafrost , 1983 .

[4]  O. Andersland,et al.  Strain Rate, Temperature, and Sample Size Effects on Compression and Tensile Properties of Frozen Sand , 1981 .

[5]  F. A. Leckie,et al.  Creep problems in structural members , 1969 .

[6]  Folke Karl Gustaf Odqvist,et al.  Mathematical Theory of Creep and Creep Rupture , 1966 .

[7]  J. Frankel.  Kinetic theory of liquids , 1946 .

[8]  L. W. Gold.  The process of failure of columnar-grained ice , 1972 .

[9]  S. Murayama,et al.  Rheological Properties of Clay , 1963 .

[10]  S. Vialov.  RHEOLOGICAL PROPERTIES AND BEARING CAPACITY OF FROZEN SOILS , 1965 .

[11]  V. Grigorieva,et al.  THE STRENGTH AND CREEP OF FROZEN SOILS AND CALCULATIONS FOR ICE-SOIL RETAINING STRUCTURES (PROCHNOST' I POLZUCHEST' MERZLYKH GRUNTOV I RASCHETY LEDOGRUNTOVYKH OGRAZHDENII), , 1965 .

[12]  F. Sayles,et al.  Creep of Frozen Silt and Clay. , 1974 .

[13]  James K. Mitchell,et al.  Creep Studies on Saturated Clays , 1964 .

[14]  F. Sayles.  Triaxial constant strain rate tests and triaxial creep tests on frozen Ottawa sand , 1974 .

[15]  A. Nádai.  Theory of flow and fracture of solids , 1950 .

[16]  Frank Garofalo,et al.  Fundamentals of creep and creep-rupture in metals , 1965 .

[17]  James K. Mitchell,et al.  SOIL CREEP AS A RATE PROCESS , 1968 .

[18]  Branko Ladanyi,et al.  An Engineering Theory of Creep of Frozen Soils , 1972 .

[19]  J. E. Dorn,et al.  Creep of Copper at Intermediate Temperatures , 1956 .

[20]  F. Sayles.  Creep of Frozen Sands , 1968 .

[21]  Samuel Glasstone,et al.  The Theory Of Rate Processes , 1941 .

[22]  S. S. Vyalov,et al.  Structural mechanics of clay soils , 1971 .

[23]  H. Jessberger.  A state-of-the-art report. Ground freezing: Mechanical properties, processes and design , 1981 .

[24]  David M. Cole,et al.  Deformation and failure of ice under constant stress or constant strain-rate , 1982 .

[25]  O. Andersland,et al.  Mechanical Properties of a Sand-Ice System , 1968 .

[26]  Orlando B. Andersland,et al.  Time-Dependent Strength Behavior of Frozen Soils , 1970 .

[27]  Anatoly M. Fish.  COMPARATIVE ANALYSIS OF THE USSR CONSTRUCTION CODES AND THE US ARMY TECHNICAL MANUAL FOR DESIGN OF FOUNDATIONS ON PERMAFROST , 1982 .