Experimental Study On The Effect Of Water Content On Mechanical Properties Of Red Clay Under Freeze-thaw Cycles

This paper takes a red clay soil in a mining area in Changzhi,Shanxi Province as the research object,takes different water content as the research condition,adopts the method of combining experimental and theoretical research,firstly,conducts expansion and contraction test and freeze-thaw cycle test,secondly,conducts repeated straight shear test,triaxial test and consolidation compression test under conventional conditions and after stabilization of freeze-thaw cycle,respectively,and finally conducts theoretical analysis to derive the research of soil related mechanical parameters,the research results show that.The expansion and contraction deformation of red clay soil has a strong mathematical relationship with water content and overlying load,and with the increase of water content,the expansion deformation of red clay soil is weakened and the contraction deformation is enhanced,and the overlying load effectively suppresses the expansion deformation of soil,which makes the expansion deformation smaller and the stabilization time shorter.When the moisture content is certain,the time of unloaded swelling stabilization basically reaches after 20 h,the time of loaded swelling stabilization decreases with the increase of moisture content,and the increase of shrinkage deformation grows linearly;with the increase of moisture content,the freezing and swelling rate gradually increases,and the freezing and thawing reaches stabilization in 6～8 times when the moisture content is low,and the stabilization times are about 10 times when the moisture content is high.In the repeated direct shear test,the shear strength of red clay gradually decreases with increasing water content,the true cohesion and cohesion under conventional conditions first decreases and then increases,and the internal friction angle gradually decreases and is close to the proposed value;after freeze-thaw stabilization,the true cohesion first increases and then decreases,and the cohesion shows a trend of decreaseincrease-decrease,and the new internal friction angle is more different from the proposed value;using the cohesion difference index ratio,it is obtained that the index ratio under conventional conditions The index ratios ranged from 0.75 to 9.96 under conventional conditions and reached the minimum at a water content of 19%,and the index ratios ranged from 1.30 to 7.13 after freeze-thaw and reached the minimum at a water content of 18%.In the triaxial test,the stress-strain curve was hardened type,and the cohesion and internal friction angle of the remodeled red clay were smaller with the increase of water content,and the shear strength indexes of the conventional conditions were greater than those after freeze-thaw cycle stabilization;the increase of water content and the effect of freeze-thaw cycle largely changed the cohesion of the red clay,which produced obvious variability of cohesion,and the internal friction angle after freeze-thaw stabilization was significantly higher than that under the conventional conditions.The internal friction angle after freeze-thaw stabilization is significantly higher than that under conventional conditions.In the consolidation test,the applied load and the variation of water content have a great influence on the consolidation and stabilization time of the remodeled red clay,and the effect is more obvious with the increase of load and water content;the compression coefficient shows a decreasing trend with the increase of water content.With the increase of water content,the elastic modulus,compressive modulus and shear modulus are decreasing,and Poisson’s ratio is gradually increasing,and the conventional mechanical parameters are greater than 10 freeze-thaw cycles to stabilize;under conventional conditions,the elastic modulus is reduced by 69.61% at most,and the elastic modulus is linearly decreasing after freeze-thaw cycles to stabilize;Poisson’s ratio is 0.21～0.29,0.24～0.31 at two cycle times,respectively;the shear modulus under conventional conditions is 0.21～0.31.The Poisson’s ratio was 0.21～0.29 and 0.24～0.31 at two cycle times;the shear modulus under conventional conditions was 1.86～1.16 times higher than that stabilized by freeze-thaw cycles,and the increase of water content made the soil more susceptible to shear deformation.Figure [37] Table[28] Reference [87]...