Study On Mechanical Properties Of Sand-containing Soft Soil Reinforced By Cement And Sodium Silicate In Coastal Area

The sand-containing soft soil has low shear strength,strong fluidity,large compressibility,large water content,and poor stability under dynamic cyclic load,so it needs to be strengthened to meet the needs of the project.In related studies,the test materials used are mainly ordinary soft soil,and the research results are not applicable to soft soil containing sand.In this paper,the sand-containing soft soil in Fujian coastal area is taken as the research object,and the cement-sodium silicate hardening agent is used to strengthen the soil.Through GDS static triaxial test and dynamic cycle triaxial test,the static property,dynamic property,deformation property and dynamic strength of sand-containing soft soil after reinforcement are analyzed.According to the experimental results,the Merchant model is improved and verified.Based on the above research,the following conclusions are obtained:(1)When the content of cement-sodium silicate curing agent is 9% and the curing time is 14 days,the cohesive force of solidified soil is 30.3 k Pa and the internal friction Angle is 31°.The larger the confining pressure is,the better the mechanical properties of the sand-containing soft soil are.The damping is going to go down step by step.The dynamic strength of solidified soil is greater than the static triaxial shear strength.(2)When the load amplitude is 76 k Pa,the dynamic modulus of the strengthened soft soil with sand is the largest and the ability to resist deformation is the strongest.When the load amplitude is 96.8k Pa,the maximum dynamic strength is 575.9k Pa.The larger the load amplitude,the greater the cumulative deformation and the greater the damping ratio.(3)The triaxial shear strength of sand-containing soft soil reinforced with cement-sodium silicate curing agent at the early stage of curing can reach 77% of the long-term strength.The curing time ranges from 10 days to 14 days,and the longer the curing time is,the faster the static properties of solidified soil increase.The longer the curing time,the worse the dynamic properties of solidified soil.When curing time is less than 7 days,the dynamic properties of solidified soil decrease the fastest.(4)The more the content of curing agent and sodium silicate,the better the mechanical properties of solidified soil.The softening phenomenon becomes more obvious.When the curing agent content is less than 9%,the mechanical properties improve quickly.The damping ratio-curing agent content curve of different loading time converges to the curve when loading 200 times.(5)When the sand content is 30%,the dynamic performance and dynamic modulus of the sandy soft soil after reinforcement are the best.When the sand content is 25%,the dynamic strength of the strengthened soft soil is the maximum,and the maximum dynamic strength is 579 k Pa.(6)Using logarithmic function to improve the Hooke element in Merchant model.The improved Merchant model has a good fit to the experimental data,and the fitting degree is all greater than 0.97.