Experimental Study On Structural Of Loess And Its Structural Constitutive Model

The problem of soil structural characteristics is called as "the focus problem of soil mechanics in the 21^st century".The loess is one kind of typical structural soil,its special structure property directly affects the mechanics and engineering property of loess. Therefore the study on the structural of loess is the main content about loess mechanics study this century.In this paper,based on the observation and analysis of a large number of literature reference,the first-class study outcomes on structural property of loess is summarized,and the essential study object of this paper are presented.Some outcomes are obtained as following:A large number of routine triaxial tests are carried out on the unsaturated soil triaxial apparatus for different water content unsaturated intact loess,disturbed loess, saturated intact loess and saturated disturbed loess.Analyzed and studied the stress-strain characteristic,volumetric strain-strain characteristic and matrix suction-stain characteristic under triaxial shear condition.The result indicates,the loess deformation property and volumetric variety property are mainly influenced by the initial water-content and consolidation stress,the water content is the most important factor on matrix suction,the disturbed loess has initial structural characteristic.On basis of a new soil mechanical method,variation characteristics of intact loess structure were studied under triaxial stress condition,and the correlation factors influencing the loess structure are analyzed.Contrasted the structural characteristics variation regularity of two Structure Parameter,the result indicates,the two Structure Parameter are unanimous.Defined a new structural parameter of disturbed loess and another saturated intact loess according to the result that the predecessor had researched previously,and studied variation regularity of disturbed loess and saturated intact loess, confirmed the applicability of the new structural parameter.Grounded on statistical damage theory,a simple damage constitutive model is presented.And carried on the comparison analysis between the test result and the model computed result,it makes clear that the model could simulate the strain softening well, the expected value is close to the strain hardening when the strain is small,the model could describe the strength and deformation behavior reasonably in a certain extent. Afford a new thinking and method of study on loess structural constitutive model.