Experimental Study On Shear And Compaction Properties Of Soils With Different Saturation

Our country has a vast territory.Under the influence of different natural geographical environments and stress historical conditions,the geological and geomorphological units are complex and the soil properties(compressive strength,shear strength,etc.)are very different.This poses a great challenge to the design and construction of basic projects.In particular,with the development of China’s national economy and the implementation of the strategy of rejuvenation of the region such as the development of the western region and the “One Belt and One Road”,many large-scale important infrastructures have emerged.The foundation soil acts as a support for the upper load,and the stability and safety of the infrastructure Is very important.As a three-phase medium,the soil will compress and deform under load.At this moment,the moisture in the soil will have an important influence on the stability of the foundation soil.Therefore,it is necessary to analyze and study the influence of different soil saturation on the properties of soil.Take the powdered soil of Beijing New Airport and the red mud of the Shanghai Red Seal Reservoir in Shangfeng as an example,through indoor experiments,the relationship between the shear strength index,dry density,and saturation is studied.At the same time,the effect of soil thickness and the number of times of roller compaction on the dry density of red mud is studied through field tests of red mud..Research indicates:(1)The cohesion and internal friction angles of the silt and red mud both increased firstly and then decreased with the increase of saturation;(2)Under the same single-click work condition,the dry density of both silt and red mud will increase firstly and then decrease with the increase of saturation.With the increase of click work,the dry density and saturation increase accordingly,but the growth rate is different;(3)According to the in-situ rolling test of the red mud filter cake,the optimal thickness of the red mud for rolling is 50 cm under the same times of roller compaction.This is due to the fact that the roller compaction energy is more fully spread within the red mud with a thickness of 50 cm,and the compaction effect is better,so the dry density is greater than 80 cm of red mud thickness;(4)Under the premise of the same rolling energy,the dry density of red mud at 50 cm and 80 cm thickness increases firstly and then decreases with the increase of the times of rolling passes.This is due to the previous times of rolling,the soil has a large deformation,soil compaction effect is sufficient,and the dry density increases.At the later stage of rolling compaction,the deformed soil has not been able to produce large deformation under the effect of roller compaction and may suffer from "springback" phenomenon,resulting in a decrease in dry density.The implementation of this study has certain significance for improving the compaction process of unsaturated soils,and it also has a certain reference for guiding actual projects.