Study On Mechainical Properties And Microstructure Of Unsaturated Soft Clay Under High Suction

In this paper,by taking the soft clay in wenzhou area as an example,the mechanical properties of unsaturated remolded soil,cement soil and polypropylene fiber soil under different suction,different initial dry density and different content were studied.And the microcosmic characteristics of soil were measured by microcosmic experiment.The main results obtained through the study of this paper are as follows:The shear strength and unconfined compressive strength of remolded Wenzhou unsaturated soft clay increase significantly with the increase of dry density,and increase logarithmically with the increase of suction.The resistivity increases exponentially with the increase of suction.The strength of cemented soil increases exponentially with the increase of initial dry density,cement content and suction,and the strength reaches 5-6 times of that of plain soil.The fiber soil increases exponentially with the increase of initial dry density and suction.When the suction is greater than 40MPa and the initial dry density is less than 1.38g/cm~3,the soil strength is the largest when the fiber content is 2‰,which is the optimal dosage.The difference of soil water characteristic curve after steam equilibrium is not significant.In cement soil,the curve increases with the increase of cement content when the suction is less than 30MPa,while in fiber soil,the curve increases with the increase of fiber content.The characteristic curves of soil and water increased slightly with the increase of dry density,and when the suction was higher than 40MPa,the curves basically overlapped.Wenzhou clay consists of a large number of agglomerates,outer particles and a small amount of open clay flocculants.In cement soil,the hydration product increases with the increase of cement content,which is connected to or filled between soil particles.The fibers and soil particles form a stable structure in the form of soil particles,and when the distribution is not uniform,the fibers tend to form slippage weak surfaces.Soil samples with a dry density greater than 1.38g/cm~3 have a single peak pore structure.When the dry density is less than 1.23g/cm~3,the soil sample has a bimodal pore structure.Regardless of the dry density and the amount of soil sample,the pore distribution between particles is basically the same,and there are some differences between the pores in the concentrated body or among the aggregates in the soil sample with small density.