Study On Mechanical Properties Of GGBS-PAM Composite Solidified Chernozem Under Freeze-thaw Cycles

Chernozem is the main soil type in the agricultural and pastoral areas of Xing'an League in Inner Mongolia.It cannot provide sufficient bearing capacity and stability when used as roadbed soil.The local replacement method is often used to solve this problem,but the replacement method not only destroys the local nature environment,and the recent step led to serious soil erosion in the local chernozem.In this paper,triaxial test,consolidation compression test,freeze-thaw cycle test,nitrogen adsorption test and ultra-depth of field test are used to study the solidification effect of different dosages of GGBS,PAM and their composites on chernozem from the macro and meso perspectives;The effects of freeze-thaw cycles on the mechanical properties of chernozem and GGBS-PAM composite solidified soil and determine the optimal content of GGBS-PAM composite solidification agent.The main work and conclusions of this thesis are as follows:1.Determine the basic mechanical indexes of chernozem through indoor geotechnical tests,determine the selection and dosage range of the curing agent based on the status quo of domestic and foreign research and the construction conditions in the agricultural and pastoral areas of Xing'an League,and explore the effect of curing agent on chernozem in a gradual and progressive manner.The best ratio.The triaxial shear test and the consolidation compression test of GGBS and PAM single blending and GGBS-PAM blending were carried out to analyze the influence of each curing agent on the mechanical properties of chernozem.Tests show that the curing effect of GGBS-PAM composite curing agent is better than single mixing curing agent.Within the test dosage range,GGBS8%-PAM0.5% and GGBS10%-PAM0.3% composite curing agents have the good curing effect..2.Perform freeze-thaw cycle tests on chernozem and two mixed GGBS-PAM composite solidified soils to study the effects of chernozem and GGBS-PAM composite solidified soil after 0,1,3,5,7,and 9 freeze-thaw cycles impact on its mechanical properties.Analyzing the stress-strain relationship,shear strength index,and elastic modulus of chernozem and GGBS-PAM composite solidified soil are affected by the effects of freeze-thaw cycles and the number of times,the results show that increasing the number of freeze-thaw cycles affects GGBS-PAM composite solidified chernozem damaged degree of the specimen is much smaller than that of the chernozem specimen.The freeze-thaw cycle action destroys the pore structure of the soil and reduces the mechanical strength and stability of the soil.The GGBS-PAM composite solidified soil has been subjected to multiple freeze-thaw cycles,and the mechanical strength is relatively large.The GGBS-PAM composite solidifying agent is determined optimal dosage is GGBS10%-PAM0.3%.3.Nitrogen adsorption test and ultra-depth of field test are carried out on mesoscopic study of chernozem and GGBS-PAM composite solidified soil.The results show that the pore structure of GGBS-PAM composite solidified soil is denser than that of chernozem and undergoes freeze-thaw cycles.After the pore volume distribution changes little,the incorporation of GGBS-PAM composite curing agent improves the internal pore structure of chernozem,increases the soil permeability,increases the consolidation coefficient,and reduces the time to complete the compression;It observation results of the depth of field microscope show that the meso-frame structure of the GGBS-PAM composite solidified soil is dense.The 3D Surface contrast image and the soil sample elevation curve also confirm that the mechanical properties of the GGBS-PAM composite solidified soil are better than that of chernozem.