Research On Engineering Properties Of Carbonate Soil Modified By Inorganic Materials

Carbonate soil has problems such as high degree of soil dispersion,large plasticity,strong expansion,and weak water permeability.Under the influence of climatic factors,due to the presence of easily soluble salts sodium bicarbonate and sodium carbonate,the carbonate soil often suffers from salt swelling,mud boiling and uneven settlement of the roadbed during road use.Therefore,carbonate soil cannot be used in actual engineering construction.In this paper,the carbonate soil in the western region of Jilin Province is taken as the research object,and the engineering properties of carbonate soil improved by inorganic materials are studied,so as to provide references and basis for its practical application in engineering.The main research contents are as follows.（1）Investigation on the distribution of carbonate soil and analysis of its basic propertiesIt was found through on-site surveys that carbonate-affected soil in western Jilin was widely distributed,with the decrease of depth,the surface soil alkalinizes and whitens,and the soluble salt content is higher,and road construction in the distribution area was severely damaged.Therefore,the representative section of carbonate soil was selected for stratified sampling.And the particle composition,mineral composition,physical properties and soluble salt content of the soil were studied.Studies have shown that saline soil has a highHCO₃^-and Na⁺content,with a pH between 9.5 and 10,and the soil is mostly alkaline,its engineering properties are reduced by the content of soluble salt.（2）Study on mechanical properties,deformation characteristics and stability of improved carbonate soilLime,lime and fly ash are used as modifiers to improve the stability of saline soil roadbed.Through strength and consolidation compression tests,with cohesion and compression coefficient as indicators,the physical changes,strength and deformation characteristics of the modified carbonate soil were analyzed.In different soil layers,the lime content is set from 5%to 17%,and the lime fly ash content is 3%to 18%.After the improvement,it can be concluded that the shear strength and compressive strength of the modified carbonated soil were improved,and the compression deformation of the soil was reduced.The frost resistance and water stability of carbonated soil were enhanced.With the increase of age,the strength of the modified carbonate soil continues to increase,its compression coefficient decreased,the compression modulus increased,and the anti-deformation ability increased.（3）Analysis of mechanical mechanism of improved carbonate soilThe change of pore structure of the modified carbonate soil was studied by scanning electron microscopy,and the physicochemical reaction between lime,fly ash and carbonate soil was studied by ion test.From a microscopic point of view,the influence of the dosage,age and salt content of the improver on the strength and deformation of the modified carbonate soil was studied.Due to the complex physical and chemical reaction between the modifier and the carbonate soil,the soil structure is strengthened,and the strength,deformation resistance and stability of the modified carbonate soil are improved.（4）Entity engineering verification of improving carbonate soilCombined with laboratory research and theoretical analysis,the improvement effect of lime and lime-fly ash on the stability of subgrade is verified through paving solid project.Studies have shown that the method of improving carbonate soil with lime and lime-fly ash is feasible to be applied in actual road engineering.