The Study On The Characteristics Of The Collapsibility In Saline Soil And The Road Performance Of Which Was Improved By Gravel

In this paper, based on the roadbed construction of Qarhan-Golmud expressway and theloop expressway in south Xi’ning, the author studied both the collapsibility of strong andexcessive saline soil and the road performance of weak and medium gravel-improved salinesoil by the method of Laboratory test, field test and theoretical analysis. The main conclusionsare listed as followings:1. Aiming at the characteristics of strong and excessive saline soil, the single-line anddouble-line tests, based on the collapsibility test of loess, were executed. Through thelaboratory tests, this paper determined the method of collapsibility test of saline soil.Meanwhile, according to the test data, we analyzed the relationship of pressure and thecollapsibility, realized the regular of differential settlement of subgrade which caused bycollapsibility of saline soil, and finally got the parameters such as the amount of collapsibility,the coefficients of collapsibility, etc. In addition, according to the collapsibility characteristics,a part of the test instruments were improved in which they could be more suitable for theindoor collapsibility tests of saline soil.2. Based on the way of ponding loading test on determining the coefficient ofcollapsibility in Technical code for building construction in saline soil regions, and combinedwith the laboratory tests, the single-line and double-line methods were used in the fieldcollapsibility tests of saline soil in Qarhan salt lake area. According to the data, this paper gotthe law of collapsibility and settlement in saline soil foundation and concluded the reasonswhy it happened by analyzing those test data.3. Improving weak and medium saline soil with gravel, regarding the intensity (modulusand CBR) as the control indicator. Through adjusting the mix proportion of saline soil andgravel, comparatively analyzing the road performance of the soil samples before and afterimprovement, and the influence on the soil gradation to it. At the same time, this paperchecked the feasibility of which if the gravel-improved saline soil could be used as theembankment fill in the expressway production, and also got the best mix proportion whichmay meet all the requirements of embankment fill.