Effects Of Soluble Salt On Loess Collapsibility In Tongxin District Of Ningxia

According to loess are widely distributed in Ningxia region, soil deep, foundation soil having large sand content, strong water sensitivity, soluble salt having high content in the soil, the collapsibility of loess is strong, after processing as building foundation. Through research of the collapsibility of loess effect, can remit and improve this kind of foundation design, construction and treatment. Currently there is a lot of qualitative research of the soluble salt collapsibility for loess affection. But the soluble salt as quantitative research very few, and the influential factors the influence degree of all kinds of salt and the law is not clear. Based on the above problems, adopting the combination of soil mechanics experiment and data analysis, orthogonal test, chart analysis, poor analysis, single factor analysis and comparative analysis methods, typical concentric loess in Ningxia as the research object, soluble salt contents s, soil dry density ρd and water content w as factors, coefficient of collapsibility ds as inspection parameters, remodeling soil sample preparation for collapsible deformation experiment research. Quantitative research from the angle of the collapsibility coefficient of soluble salt in different confining pressure under the action of consolidation effect of collapsibility loess, reveals the effect rule and mechanism, the relationship curve is established. Study concluded that:(1) the content of soluble salt CaCl2is one of the important factors influencing the collapsibility of loess, coefficient of collapsibility increases with the increase of salt content and, the loading equal, coefficient of collapsibility of soil sample decreases with the increase of moisture content and dry density.(2) in single factor test, coefficient of collapsibility of soil samples with soluble salt Na2SO4, NaCl and CaCl2concentration increases, and the different kinds of soluble salt content and fitting relation between the collapsibility coefficient curve expression is different, but the curve fitting degree is high.(3) in the comparison and analysis, when Na2SO4content in the range of0.6%-1.2%, the soil sample is bigger than the collapsibility coefficient increase other salts. In addition, along with the increase of salinity, the compound when salt content at1.7%～2.4%, the collapsibility coefficient is bigger than the increase of NaCl in the range of variation.(4) along with the increase of confining stress, the coefficient of collapsibility of loess first increases and then decreases, while with the increase of clay content, coefficient of collapsibility of soil decreased gradually.(5) through the overall analysis, soluble salts in the soil in the form of cementation material is one of the important factors affect the collapsibility of loess.