Study On Solidification And Mechanical Properties Of Peat Soil In Dianchi Lake

The high organic matter content,high natural moisture content,high compressibility and low shear strength of peaty soils in Dianchi basin make it difficult for peaty soils natural foundations to meet the needs of engineering construction,so curing of peaty soils is required.The use of traditional cement materials for curing peat soil often results in engineering problems such as low foundation bearing capacity and large deformation in foundation works of high-rise buildings and roadbed works of transportation facilities,resulting in a large amount of economic losses.This paper combines the engineering properties of peaty soil in Dianchi basin and the demand for peaty soil foundation in Kunming city development and construction,formulates a composite curing agent for the defects of peaty soil engineering properties,and compares and analyzes the mechanical properties of peaty soil after curing treatment by traditional cement and composite curing agent.The following work was mainly carried out.(1)A comprehensive evaluation of peaty soils in Dianchi basin in terms of composition,microstructure and physical property indexes was conducted,and cement,quicklime,gypsum and basalt fiber were selected to improve peaty soils with low shear strength and high deformation according to the needs in engineering properties of peaty soils.(2)To determine the range of admixtures through single admixture experiment and to explain the curing mechanism of each admixture in peaty soil.(3)To establish the regression equation for the relationship between the unconfined compressive strength of the composite curing soil and the admixture components by designing the response surface test of the composite curing agent,and to obtain the optimal ratio between the components of the composite curing agent.(4)Through the static triaxial test,the main stress difference and axial strain curves of cement cured soil and composite cured soil were compared and analyzed under different test confining pressure and admixture levels,and the molar damage envelopes of the two cured soils were plotted and the shear strength index of the two cured soils under different admixture levels was quantified.(5)The evolution of hysteresis curves,backbone curves and dynamic elastic modulus of cement-cured soil and composite cured soil under different test confining pressure,loading frequency and admixture level were compared and analyzed by kinetic triaxial tests,and the quadratic polynomial empirical dynamic constitutive models of the two cured soils were established respectively.(6)The cumulative plastic deformation characteristics of cement-cured soil and composite cured soil under long-term cyclic dynamic loading are compared and analyzed,and the cumulative plastic strain models of the two types of cured soil under the influence of dynamic cyclic cycles are established respectively.