Study On The Strength Characteristics Of The Loess

The compaction of subgrade soil has always been a very important link in engineering,the quality of compaction affects the degree of compaction of soil and then the strength of soil.Insufficient compaction will lead to post-construction settlement,cracks and other diseases,compaction is too large,the need for machinery,costs will increase.In engineering,the required degree of compaction is usually obtained by mechanical compaction to control the quality of engineering,and the maximum dry density required to obtain the degree of compaction is obtained by heavy indoor compaction work.When the field compaction function becomes larger,if the maximum dry density of indoor heavy compaction work is used to calculate the compaction degree,the phenomenon of "compaction degree exceeding 100" may occur.Different indoor compaction functions change the degree of soil compaction,which leads to the change of soil strength.Therefore,it is of great significance to study the law of soil compaction and strength change under different compaction work for guiding engineering practice.In this paper,the influence of different compaction functions of loess samples on the compactness and strength of loess under wide water content is studied by selecting loess in Xi'an area.The main contents of this paper are as follows:1?Through the laboratory compaction tests of loess samples under four different compaction work,the full compaction curve clusters of loess samples under the four different compaction work are established.Through the analysis of compaction curve,the equation of full compaction curve is introduced to establish the relationship between the physical properties of loess and the compaction curve,and the influence of the parameters in the equation on the compaction curve of loess is analyzed.2?Through the analysis of the full compaction curve,the process of predicting the compaction curve of loess sample under other compaction work is realized based on the compaction curve under one compaction work.3?Through direct shear test in laboratory,the variation law of shear strength and shear strength index cohesion,internal friction angle and water content curve of loess specimens under four different compaction work is studied.The influence characteristics of different compaction functions on cohesion and water content curve,shear strength and water content curve are analyzed.The formulas for calculating the shear strength,cohesion and water content curves are established,and the influence of the parameters in the shear strength curve equation on the curves and the variation law of the parameters are analyzed.4?Based on the analysis of shear strength and water content of compacted loess,the relationship between shear strength curve and physical properties of loess is established.Based on the shear strength curve of a certain compaction work,the shear strength curve of loess samples under other compaction work is predicted.The calculation formula can reflect the variation of shear strength and water content,cohesion and water content curves under different compaction work.