Research on variability characteristics of micropore of Zhanjiang clay under ambient temperature and pressure, normal atmospheric

Abstract

Soils are generally used as building material and foundation, are normally under the atmospheric with ambient temperature and pressure, nevertheless, effect of oxidation of soil proceeding so slowly that it is no easy to perceive, long-term deterioration of soil properties, cannot be ignored. Zhanjiang Clay was taken as the object of study, studied the reformation effect on the micro-structures under the influence of the atmospheric and its impacting mechanism to soil properties, by scanning electron microscopy, mercury intrusion porosimetry and nitrogen absorption method. Research shows, after oxidized, the color of soil changes from grayish green and light grayish green to yellow and yellowish brown; while aggregation of soil particles increases, not only Swelling-shrinkage properties, but also plasticity of soil particles decreases, as for the sensitivity and structure yield strength reduced. Furthermore, atmospheric environment has an effect of shrinkage and closure on pores (<italic>d</italic><0.1 μm), and enlargement and dispersion on pores (<italic>d</italic>>1 μm), which results in a decrease of total pores volume of oxidized clay. As far as pores (<italic>d</italic>>1 μm) are concerned, pores volume increases remarking, with appearance of fracture porosity and reduction of ink-bottle type pores, as well as conversion from open pores to close ones. The transformation of soil properties by the influence of atmospheric is not caused by inherent changes of mineral, but the remodeling effect of micro-structures because of motion effects and chemical reactions of water-soil-electrolytes- atmosphere leading to coupling and transforming of soil particles. It is the variation of ultra-micro-structure that generates this phenomenon. Prolonged influence with comparatively large potential harmful impact on soil stability caused by damage effects on structural strength during oxidation, it turns out to be necessary to strengthen monitoring the effect on geotechnical engineering of physical and chemical factors in environment.