Experimental study on dynamic evolution of meso-structure of intact Q₃ loess during loading and collapse using CT and triaxial apparatus

To disclose the variation of meso-structure of intact Q3 loess during loading and collapse, a series of CT scanning-triaxial collapsible tests with controlled suction are done using triaxial apparatus for collapsible soils combined with computer tomography. Not only the macro response curves but also the corresponding images of CT scanning are obtained. It is indicated that the intact collapsible loess has apparent fabric; bigger holes expand, then close; smaller holes gradually close during loading; most of holes gradually close and the distribution of density of scanning section becomes homogeneous in the process of collapse; and whether the bigger holes close or not is decided by the stress condition of immersion. On the basis of analysis of macro and meso experimental materials, the yielding stress of fabric of the intact collapsible loess is determined, a structural parameter is developed based on the mean of CT values, structural damage variables in the process of loading and collapsing are individually defined, the changing law of variables is studied and equations of structural damage evolution are established.