Effect Of Time On Remolded Loess Collapsibility In Tongxin District Of Ningxia

Loess is a kind of special structural soil with strong regional characteristics, which shows its unique collapsibility after the soaked by water, because of its collapsible, the loess is often needs to be treated as the foundation of the building. After the treatment of loess foundation, the structure is subjected to different degrees of disturbance, which has the characteristics of the remolded loess, and the sampling and determination of the collapsibility has the problem of time node. For the aging of remolded loess, combining with the research status of loess and the characteristics of collapsible loess of Ningxia,taking water content, dry density and soluble salt content as factors, designing the orthogonal test scheme L16(45), preparing structural remodeling soil samples, using full automatic pneumatic consolidation to test apparatus to do the indoor wet sinking test, adopting the combination of soil mechanics experiment and data analysis method, studying on considering the effect of one kind of soluble salt and two kinds of soluble salts compound on the collapsible aging of remolded loess in Ningxia Tongxin by experiment. The relation model is established between the collapsible aging and experimental factors by analyzing the law and mechanism of action by the least square fitting. Experimental results show that:(1) the remolded loess collapsibility coefficient decreases with the increase of moisture content and dry density, and increases with the increase of soluble salt content. (2) The remolded loess collapsibility aging parameters decreases with the increase of moisture content, dry density and soluble salt content. (3) The collapsible aging parameter increases with the increase of age, fast in the initial stage, slowly in the later stage. It tends to be basically stable after 14 days, so 14d can be used as the time point of measurement and evaluation of the collapsibility of remolded loess. (4) Moisture content, dry density and soluble salts content have significant effect on the collapsibility Coefficient and collapsible aging of remolded loess, and the importance order of the influence is dry density, moisture content and soluble salt content. (5) The remolded loess collapsibility coefficient and collapsible aging influence degree of different soluble salts are different, and the order of affection is: composite salt>Na2SO4>CaCl2. (6) The collapsible aging and age of the remolded loess is in a hyperbolic relationship, the model of collapsible aging is remarkable, which has a good correlation with water content, dry density, calcium chloride content and age, and the predictive value is credible. The research results have important significance for the collapsibility evaluation of remolded loess foundation.