Physical And Mechanical Properties Of Modified Soil And Its Application In Raw Soil Construction

This paper takes the earth building as the research object.Because the earth materials have the advantages of local materials,economic saving,green environmental protection and so on,they are often regarded as green building materials,but the earth materials have shortcomings in physical mechanics and safety stability,which limits the development and application prospects of earth materials.Based on the theory of laboratory test,model test,microstructure test and study on comprehensive evaluation of engineering performance,this paper studies the engineering characteristics and suitability evaluation of traditional modified soil in the whole restoration of ancient city wall soil site.The main conclusions are as follows:(1)The traditional modified materials(sticky rice juice,straw,lime,cement,sand,tung oil)were added to the plain soil according to a certain proportion,and the engineering characteristics of the plain soil were improved to varying degrees,in which the shear strength increased about 1.3?3.5 times,and the impermeability increased 3?1650 times.(2)The stress-strain control triaxial apparatus was used to test the unconfined compressive strength of 8 typical modified soil cylindrical samples with an age of 1 d?7d?14d?28d.(3)The denudation resistance of different modified raw soils is 1.3?12.5 times higher than that of plain soils.7%sticky rice mortar 0.6%straw modified soil and sticky rice mortar tung oil modified soil have the best ability to improve the durability of plain soil.(4)Through the capillary lifting test,the relative capillary water lifting height of plain loess decreased after the addition of appropriate proportion of modified materials.The maximum capillary water lifting height of plain soil reached 113.4cm in the nine kinds of soil,and the lifting time was 46d.The capillary water lifting height of sticky rice mortar+tung oil modified soil reached the minimum of 27.2cm among the nine kinds of soil,and the lifting time was 24 days.(5)Through microscopic tests,the addition of modified materials can improve the microstructure of plain soil,increase its cementation strength,increase the number of small pores,change the arrangement of skeleton particles,and achieve the purpose of enhancing the strength of modified soil macroscopically.(6)Analytic Hierarchy Process(AHP)and fuzzy mathematics theory were used to comprehensively evaluate the weights of six indexes,including safety,durability,moisture absorption and desorption characteristics,impermeability,economy and construction difficulty.Two kinds of A-grade modified soil materials were obtained by fuzzy evaluation analysis:7%sticky rice mortar modified soil,sticky rice mortar tung oil modified soil.It is used in the rammed soil structure engineering of earth building,and the modified soil is used to build it,which has outstanding advantages in its physical and mechanical stability and livability.