Strength And SHPB Test Analysis Of EPS Lightweight Mixed Soil In Chloride Environment

In actual engineering,backfill soil is often affected by complex environments such as chloride erosion,dry-wet cycle,and freeze-thaw cycle,and is prone to damage and damage.EPS lightweight mixed soil has many excellent properties such as light weight,adjustable strength,fast hardening and forming,good thermal insulation performance,strong plasticity,and convenient construction.In this paper,the EPS lightweight mixed soil obtained by mixing 15%cement,15%fly ash and different volumes of EPS particles into the clay of a foundation pit in Huainan was taken as the research object,and different chloride concentrations（clear water,4.5 g/L,9 g/L,18 g/L）,different dry-wet cycles（0,3,6,9,12,15）and freeze-thaw cycles（0,3,6,9,12,15）The unconfined compressive strength and SHPB uniaxial impact test are used to analyze its strength and deformation,mass loss,longitudinal wave velocity,energy loss,microstructure,etc.（1）The unconfined compressive strength test of lightweight mixed soil under different EPS volume content（0,10%,20%,30%,40%）was carried out,and the density and unconfined compressive strength of the soil samples were analyzed.Variation law of compressive strength and stress-strain curve.The results show that with the increase of the EPS content,the density of the mixed soil decreases gradually but the decreasing trend slows down,and the strength loss continues to increase;the appropriate EPS volume content of the mixed soil is 30%,and the sample density and unconfined compressive strength are respectively It is 1.44 g/cm3 and 1.98 MPa.（2）The unconfined compressive strength test and the SHPB uniaxial impact test of the mixed soil samples under different chloride concentrations,different dry-wet cycles and freeze-thaw cycles were carried out,and the dry-wet cycles and freeze-thaw cycles were analyzed.Influence law on mass loss,longitudinal wave velocity,unconfined compressive strength,dynamic mechanical properties and energy dissipation of mixed soil samples under chloride-salt erosion.The results show that with the increase of dry-wet cycles and freeze-thaw cycles,the mass of mixed soil samples and the velocity of longitudinal waves are lost to varying degrees,and the loss rate first decreases and then increases.The static unconfined compressive strength,dynamic compressive strength and absorbed energy all decrease with the increase of the number of actions.When the sample is damaged by impact load,its dynamic compressive strength is generally higher than the static unconfined compressive strength,and the dynamic failure strain is smaller than the static failure strain.（3）Under the same cycle and number of actions,the mass and longitudinal wave velocity of the mixed soil samples in clear water are generally lower than those in the chloride salt soaked samples,and the unconfined compressive strength and dynamic compressive strength increase with the concentration of the solution.increases,the intensity gradually decreases.After soaking in clean water and different chlorine salt concentrations（4.5 g/L,9 g/L,18 g/L）,after 15 dry-wet cycles,the no-lateral compressive strength of the sample decreased by 14.50%,17.67%,respectively.%,18.30%,20.19%,the dynamic compressive strength decreased by 25.98%,26.82%,28.21%,31.56%respectively;%,26.81%,37.85%,and the dynamic compressive strength decreased by41.06%,43.86%,45.53%,and 55.87%,respectively.With the increase of the concentration of chloride salt,the ability of Cl^-to combine with the internal hydration products of the sample is enhanced,and a slightly water-soluble compound salt is formed,which consumes a large amount of hydration products,resulting in a decrease in the strength of the sample.（4）From the perspective of microstructure,the damage mechanism of macroscopic mechanical property degradation of mixed soil under the action of chloride salt erosion,dry-wet cycle and freeze-thaw cycle was analyzed.The results show that the dry-wet cycle and the freeze-thaw cycle cause fatigue damage such as loose internal structure of the mixed soil,enlarged pores,new cracks and expansion,and Cl^-in the solution enters the interior of the sample along the cracks and pores,and combines with the cementitious material.Ca²⁺and internal hydration products generate a large amount of molten salt,which reduces the formation of hydration products and reduces the bonding between internal aggregates,resulting in a decrease in macroscopic mechanical strength.Figure[40]Table[14]Reference[84]...