Study On The Deformation Characteristics Of Liquefied Sands Reinforced By Different Piles Based On The Shaking Table Test

The problem of the liquefaction has always been an important research in geotechnical engineering,gravel pile and cement-soil pile are widely applied in foundation treatment.The effects of Gravel pile are drainage,compaction and improve vertical bearing capacity,which widely recognized in the event of engineering.But the mechanism of liquefaction resistance still is insufficient,lacking of scientific test certification.This article relies on the national natural fund project " the test research of the mechanism of liquefaction of sandy soil by pile reinforced "?project no.50578104?,shanxi bureau of science and technology project "the loess area,the mechanism research of liquefaction reinforced by pile resistance "?contract no.10-1-06?and the open fund project of loess research institute in Shanxi "the test research of the bearing properties of pile in the layer of liquefaction soil foundation "?KLTLR-Y13-3?,the reinforcement mechanism of the liquefied soil foundation as the research background,on the1:18 similar geometric ratio,the range of the study is 8.64 m below the surface which within the scope of the sandy soil liquefaction of soil layer,with shaking table test of the three liquefied soil model,which are cement-soil pile,gravel pile,and the combination of gravel pile and cement-soil pile.Come to a conclusions are the pore water pressure,earth pressure and displacement time history curve.the conclusions are as follows:Macroscopic phenomenas reflect:?1?No matter which kind of reinforcement models,under the action of cyclic loading,the top of piles are drainage,and with the increase of the number of gravel piles,the surface displacement is increasing and the surface subsidence is increased.At the end of the vibration,the sand dunes are appearing,and the overall surface is concave,After the test found digging: gravel pile reinforcement model the upper soil is but lower progressively;The soil in the upper part of the soil is dense,and the middle and lower soil is in a state of flux.The composite reinforcement model of gravel pile and water soil pile is reinforced,and the whole model soil is more compact when excavated.The analysis of pore water pressures:?1?No matter which kind of reinforcement model,pore water pressure is increase to the peak and few seconds later,began to slow down until the end of the test;?2?In the same kind of reinforcement model,the pressure of pore water increases with buried depth.?3?Under the same location,reinforced cement-soil pile model of pore water pressure is the largest,composite pile reinforcement model followed,gravel pile reinforcement model is minimum,which is because gravel pile provides good drainage channel for helping to dissipation of pore water pressure.The analysis of earth pressure:?1?No matter which kind of reinforcement model,earth pressure along with the vibration load fluctuates up and down in the static pressure,after a few seconds,the vertical earth pressure along with the vibration quickly dropped to the minimum,then until the end of the test to fixed value fluctuation;At the same level,the soil pressure at 0cm was minimized,and then is-14 cm,and the amount of soil pressure in 14 cm was the largest.?2?the same reinforcement model deepens unceasingly along with the depth increase;?3?the same location,earth pressure of gravel pile reinforcement model is the biggest,reinforced cement-soil pile composite pile reinforcement model of minimum,shows that the same conditions,the composite piles in the reinforcement model the largest share of earth pressure.?4?Sorting earth pressure and buried depth,the relationship between the level of satisfaction:P=z₀+ax+by+cx²+dy²+fxy?y-/cm depth;x-level/cm;earth pressure P-/kPa;z0,a,b,c,d,f-coefficient related to the reinforcement model?,It can be used to calculate the earth pressure in any position.The time history curve of settlement:?1?No matter which kind of reinforcement models,the settlement is unchange in a few seconds,with the vibration continues,the settlement increases rapidly,and then keep this value to the end of the test;At the same level,0cm is the largest settlement,minus 14 cm,the lowest settlement in 14 cm.?2?In the same reinforcement model,with the buried depth deepening,the curvature of the plane concave sink more and more small,the 12 cm depth plane sank concave curvature is the largest,24 cm is buried deep in the concave curvature of The Times and sank 36 cm buried deep concave curvature minimum;With the increase of buried depth,the decrease of the settlement in constant,horizontal position 0 cm settlement with buried depth can reduce rate of maximum,and-14 cm and 14 cm settlement with buried depth can reduce rate of basically the same;In the same position,the settlement of gravel pile reinforcement model is the least,the settlement of composite pile reinforcement model is the second,the water soil pile reinforcement model is the largest.?4?settlement and horizontal position and depth of the relationship is: S=z₀+ax+by+cx²+dy²+fxy?y,buried depth,unit cm;x-a horizontal position,unit cm;S-settlement,unit mm;z₀,a,b,c,d,f-coefficient related to the reinforcement model?.This can be used to calculate the amount of sedimentation in place.In any case,no matter what kind of piles reinforcement models,the center of the pile is prone to expand and fracture to the maximum level of vibration.The same location,the composite pile pile in the reinforcement model share the biggest earth pressure;The same buried depths,the settlement of reinforced cement-soil pile is greater than the composite pile,crushed stone pile reinforcement of minimum,gravel pile reinforcement is advantageous to the pore water pressure dissipation.Therefore,from the level of resistance force,vibration reduction,the settlement reducing comprehensive factors,such as suggested practical engineering to consider in the form of gravel pile and cement-soil pile composite reinforcement reinforcement of liquefied soil.