CONSTITUTIVE EQUATION FOR CYCLIC BEHAVIOR OF COHESIVE SOILS

Endochronic theory is employed to develop a relatively general constitutive relationship to model the dynamic behavior of cohesive soils subjected to multi-dimensional stress or strain paths. The proposed constitutive law is capable of describing (a) strain softening and hardening, (b) densification and dilatancy, (c) frictional aspects, and (d) rate dependence of the stress-strain behavior; it also accounts for pore pressure response in undrained conditions by considering saturated soils as two-phase media. The theory is based on a series of new internal state variables that are defined in terms of semi-empirical intrinsic material relationships, and it is able to handle elastic and inelastic strain histories for rate-dependent materials from the very beginning of their cyclic stress-strain path. The intrinsic relations involve ten material parameters, including the initial elastic modulus, which must be determined from a quasi-static and cyclic tests. Although limited data preclude the development at this time of specific correlations for the material parameters in terms of soil characteristics, this model offers a significant improvement in the interpretation and analysis of the cyclic behavior of cohesive soils. The mathematical model is applied to describe data from low-frequency cyclic constant-strain-rate tests on undisturbed samples and low-frequency cyclic constant-load-amplitude tests on slurry-consolidated samples of kaolin; both types of test were conducted under undrained triaxial conditions with pore pressure measurements. Emphasis is directed toward the behavior of cohesive soils under low-frequency, large-strain cyclic conditions, such as those associated with earthquakes. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 557-568

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Filing Info

  • Accession Number: 00179767
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM