Guilin Longsheng Phyllite Eluvial Soil Of One Dimensional Compression Test Research

Phyllite eluvial soil as a regional special soil and distributed mainly in the west of our country,the south,such as in northern guang xi.Because of its low mechanical strength,easy to soften,easy disintegration,and strong water sensitivity,under the condition of rainfall to geological disasters such as landslide,collapse,debris flow,also easy to make high in phyllite eluvial soil formation compression deformation is large,which brings the problems such as foundation uneven settlement.Under the natural condition,phyllite eluvial soil mostly in unsaturated condition,Moisture content had a great influence on physical and mechanical properties of soil,and exploring its water-holding characteristics is helpful to carry out other mechanical studies,to reveal the mechanism of deformation of soil mass.Therefore,in this paper,phyllite residual soil in Long sheng county,Guilin city is taken as the research object,the water-holding characteristics of phyllite residual soil with different dry densities are studied,and the water content and pore water distribution of soil are analyzed from the microscopic point of view with the help of nuclear magnetic resonance analyzer,use a K₀ consolidation apparatus for phyllite eluvial soil of one-dimensional K₀ consolidation test,to explore the different initial density and water content on the compression characteristics and the influence law of coefficient of earth pressure at rest.The results show that:（1）Phyllite eluvial soil dry density is larger,the greater the inlet value and residual saturation,the water feature is better,but the dry density in middle and low suction parts have obvious effects on the water features,and has little effect at high suction part;Using GA、VG and FX model of phyllite eluvial soil of SWCC curve fitting,found that the fit of the three model is very high,and FX model fitting effect is the most ideal;Phyllite eluvial soil is bimodal pore structure,is mainly composed of small pore and a small number of large pores,dry density is smaller,the more the number of macropore in soil samples.Under the effect of suction,the free water priority from big pore eduction and then to the small pore.（2）The initial density and soil water content had a great influence on the compression feature.The initial dry density,the greater the soils tend to be dense,the soil particles is more difficult to move,small deformation under pressure,the smaller the compressibility of the soil;Can enhance the strength of soil suction,and suction decreases with the increase of saturation its e-lg p curve is down,compressibility is increased.（3）The phyllite eluvial soil of the change of the coefficient of earth pressure at rest in the loading and unloading phase is different,in the loading stage,affected by cementation,static earth pressure coefficient first decreases with increase of vertical stress to stabilise after increasing.During the unloading phase,because there are residual stress level,the coefficient of earth pressure at rest with the vertical stress increases;The initial dry density and saturation,the greater the loading phase of the static earth pressure coefficient also increases with.And the coefficient of earth pressure at rest of the unloading phase depends mainly on the soil stress history,the initial dry density and saturation.