| It’s an important way for the transport and infiltration of heavy metals to enter the soil by water.The mechanical and physicochemical properties of the soil will be changed to varying degrees after heavy metal pollution,which will cause damage to the surrounding roadbed.As an unique soil,silty soil has strong capillarity,and heavy metals are more easily transported into the soil through capillary water,which has an impact on the stability of silty soil roadbed.In this paper,Kaifeng silty soil was taken as the research object.By preparing the samples of silty soil with different contents of heavy metal chromium and copper ions,the following contents are studied by using methods of laboratory test,microscopic test and numerical simulation.(1)The basic properties of silty soil were explored through particle size analysis test,boundary moisture content test,X-ray diffraction test,compaction test and direct shear test.(2)After preparing the heavy metal ions solution and conducting the capillary water rising test on silty soil,the variation law of capillary water rising height under different compaction degree and water content at different height were obtained.By comparing the capillary water test results of non-polluted water,the influence of heavy metal ions incorporation on capillary water rising law was obtained.In addition,the flame atomic absorption spectrophotometry was used to detect the content of heavy metal ions in the soil samples after the test,which served as the basis for the heavy metal ions ratio of the soil samples in the follow-up test.(3)The compaction test,unconfined compressive strength test and direct shear test were carried out on silty soil samples with different contents of heavy metal chromium and copper ions.The effects of heavy metal ions on the shear and compressive properties of silty soil were obtained,and the values of cohesion and internal friction angle were measured.(4)The X-ray diffraction and scanning electron microscopy tests were carried out on silty soil samples with different contents of heavy metal chromium and copper ions.The variation rules of peak phase and surface morphology characteristics of each soil sample were obtained,and the reasons of strength change of each soil sample were analyzed from a micro-perspective.(5)According to the variation law of parameters obtained from indoor test results,the deformation of silt subgrade before and after pollution was simulated by ABAQUS finite element software.The variation law of vertical deformation and shear stress of silt subgrade after pollution by heavy metal ions was obtained,and the influence of heavy metal ions on the stability of silt subgrade was expounded. |
