STRESS-STRAIN RELATIONSHIPS AND NONLINEAR MOHR STRENGTH CRITERIA OF FROZEN SANDY CLAY

ABSTRACT A series of triaxial compressive tests were performed on frozen sandy clay at -4 and -6°C under confining pressures from 0 to 18 MPa. The experimental results indicate that the stress-strain curves show strain softening and hardening phenomena when the confining pressures are below and above 3.0 MPa, respectively. Since the generally hyperbolic model can not describe the strain hardening behavior very well and the Duncan-Chang model can not ideally describe the strain softening behavior of the frozen sandy clay, an improved Duncan-Chang model is proposed. This model can describe not only the strain softening behavior but also the strain hardening behavior of the frozen sandy clay, and the calculated results are rather coincident with the corresponding experimental data. In addition, it is also suitable for frozen silty clay with a high precision. Due to pressure melting, the shear strength of the frozen sandy clay changes nonlinearly with increasing confining pressures. In order to solve the problem that the linear Mohr-Coulomb criteria can not exactly reflect the shear strength of the frozen sandy clay, a nonlinear Mohr criteria of the frozen sandy clay is presented. The calculated results illustrate that it has higher precision and can describe the shear strength of frozen sandy soils more accurately than the linear Mohr-Coulomb criteria does.

[1]  Hugh M. French,et al.  The Periglacial Environment , 1977 .

[2]  Gunnar Aas,et al.  Laboratory Determination of Strength Properties of Frozen Salt Marine Clay , 1981 .

[3]  Lukas U. Arenson,et al.  Triaxial constant stress and constant strain rate tests on ice-rich permafrost samples , 2005 .

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

[5]  W. Ma,et al.  Analyses of behavior of stress–strain of frozen Lanzhou loess subjected to K0 consolidation , 2004 .

[6]  Yuanming Lai,et al.  Yield criterion and elasto-plastic damage constitutive model for frozen sandy soil , 2009 .

[7]  Lukas U. Arenson,et al.  Mathematical descriptions for the behaviour of ice-rich frozen soils at temperatures close to 0 °C , 2005 .

[8]  Wei Ma,et al.  Analyses of strength and deformation of an artificially frozen soil wall in underground engineering , 2002 .

[9]  J. M. Duncan,et al.  Nonlinear Analysis of Stress and Strain in Soils , 1970 .

[10]  Takuo Yamagami,et al.  The effect of strength envelope nonlinearity on slope stability computations , 2003 .

[11]  Y. Lai,et al.  Volumetric strain and strength behavior of frozen soils under confinement , 2007 .

[12]  Jean-Pierre Bardet,et al.  Experimental Soil Mechanics , 1997 .

[13]  R. Baker,et al.  Nonlinear Mohr Envelopes Based on Triaxial Data , 2004 .

[14]  Yuanming Lai,et al.  Strength distributions of warm frozen clay and its stochastic damage constitutive model , 2008 .