Dynamic Triaxial Test Research Of Saturated Silty Soil Subgrade Under The Structure Of Low Embankment With High Water Level

This paper is in the engineering background of the highway project called Xi Niu Jiao in Guangxi coastal.Because the underground water level is high,we proposed to use the design of low embankment after considering the terrain and geological conditions of that road.Subgrade is mainly composed of silty sand,and the liquefaction and deformation of saturated silty soil may happen under the action of continuous vehicle load which will hold up traffic safety.Therefore,this paper not only studied the the laws of liquefaction and deformation of saturated silty soil subgrade under the structure of low embankment with high water level,but also studied the controlling measure of liquefaction and deformation of saturated silty soil.In early research,we designed some structure processing models of subgrade,and obtained the characteristics of the liquefaction resistance and deformation resistance by computer simulation.Based on the models which have obvious effects on liquefaction resistance and deformation resistance,we design three specimens of dynamic triaxial test(untreated model sample,horizontal treated model sample and vertical treated model sample)and use the GDS dynamic triaxial apparatus to load application which simulates the vehicle load on the specimens of saturated silty soil in order to research the dynamic characteristic of differernt treated model samples under different consolidation ratio,consolidation pressure and the dynamic frequency.After comparing the test results,we got the laws of liquefaction and deformation.And we also got the structure processing models' control effects of liquefaction and deformation resistance of saturated silty soil.The main content of this paper is as follows:(1)The dynamic deformation of three model samples:When the consolidation ratio and frequency remain unchanged,the dynamic deformation of three model samples decreases while consolidation pressure increases.When the consolidation ratio and consolidation pressure remain unchanged,the dynamic deformation of three model samples decreases while frequency increases.When the consolidation pressure and frequency remain unchanged,the dynamic deformation of the untreated model samples decreases while consolidation ratio increases,and the dynamic deformation of horizontal and vertical model samples increases while consolidation ratio increases.(2)The dynamic strength of three model samples:When the consolidation ratio and frequency remain unchanged,the dynamic strength of three model samples increases while consolidation pressure increases.When the consolidation ratio and consolidation pressure remain unchanged,the dynamic strength of three model samples increases while frequency increases.When the consolidation pressure and frequency remain unchanged,the dynamic strength of the untreated model samples increases while consolidation ratio increases,and the dynamic strength of horizontal and vertical model samples decreases while consolidation ratio increases.(3)The liquefaction resistance of the untreated model samples:When the consolidation ratio and frequency remain unchanged,along with the increase of consolidation pressure,pore pressure of the untreated model samples increased to a certain amplitude required time longer and longer.When the consolidation ratio and consolidation pressure remain unchanged,along with the increase of frequency,the developmental rule of pore pressure of the untreated model samples is the same as above.When the consolidation pressure and frequency remain unchanged,along with the increase of consolidation ratio,the developmental rule of pore pressure of the untreated model samples is the same as above.(4)The effects of processing models:When Kc =1.0,both of the horizontal and vertical processing model can improve dynamic strength of saturated silt subgrade effectively,reduce the soil deformation,prevent the liquefaction.When Kc?1.25,because the large difference of material propeties between the processing material and saturated silty soil,there will come up large slippage between the interface of them.That will reduce dynamic strength of horizontal and vertical processing subgrade and increase the deformation of soil.So when selecting the materials of structural processing,the materials properties of which are similar to the soil should be selected to achieve the desired effect.