Artificial Preparation Of High Liquid Limit Structured Soft Soil And Its Strength And Deformation Characteristics

Natural structural soft soils often show the characteristics of high water content,large void ratio,low strength,high compressibility,and structural properties.This type of soil has strong compressibility and slow consolidation process,which makes the foundation of buildings unstable and constructional.Problems such as post-settlement are significant.In view of the fact that the original samples of natural structural soft soils are not easy to prepare,the artificial preparation of structural soft soils with mechanical properties similar to those of natural structural soft soils is undoubtedly of great significance for its unit and modeling research.This article intends to conduct one-dimensional consolidation,triaxial compression and tensile tests on artificially prepared high-liquid-limit macroporous structural soft soils(with a certain initial porosity and cement strength)indoors with controllable liquid and plastic limits to verify the indoor preparation of high-liquid The feasibility of structured soft soils with restricted large pores,and the compression deformation characteristics and physical and mechanical properties of structured soft soils with large pores with high liquid limit are studied.The main work carried out in this paper is as follows:(1)Using raw material soil(silt soil),diatomaceous earth,kaolin,calcium bentonite,cement and urea as preparation materials,taking Japan’s Osaka Bay marine natural soft soil as the main reference target,artificially prepared structural soft The optimal ratio of soil.Through the combined determination of liquid and plastic limits and the comparison of the five groups of formulas,the optimal ratio content is determined to be 35%of raw material clay,5%of calcium-based bentonite,20%of kaolin,25%of diatomaceous earth,10%of urea and 5%of cement.(2)The strength and deformation of physical and mechanical indexes of artificially prepared structural soft soils were tested through tests such as one-dimensional compression,triaxial compression and triaxial tension.The void ratio e of the sample was 1.7,and the liquid and plastic limits were _Lw=75.9%and w_P=31.7%;the M values of triaxial compression and tensile strength are 1.34 and0.87;the compression indexλand the rebound indexκare 0.672 and 0.092.The void ratio,liquid-plastic limit,strength index and deformation index of the artificially prepared structured soft soil are close to the target natural soft soil,which verifies the controllability and stability of the preparation method.(3)Through the experiment of different proportions,the factors affecting the liquid limit of the soil and the relationship with the strength of the soil were studied,and it was concluded that the difference of the liquid limit of the mixed soil with different proportions could reach 43%,among which diatomite,kaolin and calcium Base bentonite has the greatest influence on the liquid limit of the mixed soil,and the content of the three is positively correlated with the liquid limit of the mixed soil.In addition,the strength indexes of structured soft soil under different liquid limit conditions are different.The corresponding peak strengths of the low liquid limit soil sample A-1 and the high liquid limit soil sample A-4 are 148.78k Pa and 92.98k Pa,respectively.(4)In combination with actual engineering cases,triaxial tests were carried out on artificially prepared high liquid limit macroporous structural soft soil samples at a constant strain(loading)rate,including conventional triaxial compression(CTC)and tension(CTE)Tests,decompression triaxial compression(RTC)and tensile(RTE)tests,and iso-P triaxial compression(PTC)and tensile(PTE)tests under different consolidated confining pressures of 50k Pa,100k Pa and 200k Pa.Analyzing the M value of the compression test is between 1.2-1.34,the M value of the tensile test is between 0.87-0.97.(5)The upper load surface Cambridge model is used to simulate triaxial compression and tensile tests under complex stress paths,and the numerical simulation curve is basically consistent with the actual test curve.The soil model index parameters calibrated by the indoor test can be applied to the unit test and the boundary value Problem simulation.