Engineering Geological Properties And Disturbed State Model For Chifeng Loess

Loess is a kind of special loose debris formed in quaternary period. It’s maincomponents is silt and it is rich in calcium carbonate. Loess Has obvious structural strengthand Vertical joints, and the large pore is visible. The loess shows collapsibility In wetconditions or under a certain pressure or the presence of both.Take Loess in Chifeng areaas the object, combined with field investigation, laboratory test, numerical simulation andmany other test means, research on the material composition, structurecharacteristics,mechanical properties and the deformation rule of loess.Analysis theinternal microstructure evolution law Under external load. Establish the loess constitutivemodel based on the disturbed state concept:(1) Chifeng loess particles is given priority to silt, followed by the clay.The diameterfrom0.005mm to0.075mm is accounted for85%, and the particle size less than0.005mm is11%.Minerals of loess are mainly composed of detrital minerals and some clayminerals.The Soluble salt in research area is given priority to Sulfate andbicarbonate.Microstructure type of Loess is mainly Mosaic micropore structure with asmall amount of coagulum cementation structure.The loess particle morphology is granularand massive particles, in addition with some flaky particles.There are two contact ways ofLoess particles: Surface to surface and surface to point.Pore of the loess is of large numberand in irregular shape or aperture shape(2) The average moisture content of Chifeng loess is14.6%, the natural density isfrom1.68g/cm3to1.68g/cm3, void ratio ranges between0.771to0.846.(3) The stress-strain curve of loess under CD conditions is geared to strain hardeningtype.(4) The collapsibility coefficient of loess has a large range, the initial moisturecontent has a significant influence on collapsible deformation. (5) To measure Chifeng loess pore size by mercury injection test. The loessporosity was35.5%, of which4μm-40μm pore number is in the majority.(6)Based on the disturbed state concept theory, the perturbation function was definedby deformation modulus, bulk modulus and shear modulus, respectively, and the evolutionlaw of perturbation function was also studied. Through the triaxial consolidation drainedshear test of both intact loess and remolded loess under different confining pressure, thedouble parameters perturbation function considering both shear strain and volumetric strainwas built and which presented an exponential function trend. And disturbance functionparameters values of both shear strain and volumetric strain were obtained by least squaremethod; moreover, the relationships between various parameters and confining pressurewere also analyzed.