Study On The Influencing Factors Of Structural Properties Of Loess In Xianyang

Loess is a typical structural soil formed under the arid and semi-arid condition, its special structure affects the characteristics of engineering mechanics of loess. In this paper, loess in Shaanxi Xianyang is taken as the research object, combining laboratory experiments and theoretical analysis to study the influencing factors of structural properties of loess. Using confined compression test with the help of comprehensive structural potential and constitutive loss to analyze the variation law of loess structure under different moisture content, calcium carbonate content and dry density. Qualitative and quantitative analysis are performed for the micro-structure by using scanning electron microscopy and mercury intrusion porosimetry to explain the evolution of its internal structure.First of all, based on the compression characteristics of loess, taking confined compression test through undisturbed loess and disturbed loess to analyze and discuss their deformation characteristics of different influencing factors under different pressure conditions. The results show that the compression curve of undisturbed loess(e~lgP curve) reaches the turning point at the pressure of 50 kPa. The kind of deformation increasing with the increase of stress confirms the presence of structural loess.Secondly, on basis of a new soil mechanical method, calculating comprehensive structural potential and constitutive loss through confined compression tests to analyze the change rule of structural parameter under the effect of each influencing factor(moisture content, calcium carbonate content, dry density). The results show that the two structural parameters can reflect the variation trend of loess structure characteristics well. The moisture content increased and the content of calcium carbonate decreased weaken the structure of loess. Whereas, the initial dry density decreased strengthens the structure of loessAnd then, carry on the quantitative analysis on the structural factors of loess by mathematical method. The coefficient of variance is adopted to determine the weight of loess structure characteristics from the statistical point of view. Results indicate that the influence of moisture content on the structure is the most obvious, dry density and the content of calcium carbonate come second. The structure of loess in Xianyang has a strong sensitivity to moisture content. It is necessary to pay attention to this factor, so as to avoid the occurrence of accidents in practical engineerings.Finally, using scanning electron microscopy and mercury intrusion porosimetry to observe and analyze the internal structure change of loess.Describe the internal structural changes through qualitative and quantitative analysis from the perspective of the evolution of the micro-structure features.