Study On Dynamic Characteristics Of Frozen Cement Soil Under Impact Load

China has entered a new stage of economic and social development,with the impalementation of the western development strategy,including Sichuan Tibet Railway as a typical representative of some major infrastructure construction projects in the frozen regions,and more and more rail transit construction projects i artificial freezing method.However,most of the researches on frozen soil structure at home and abroad are focs ed on frozen soil structure,and there are few researches on physical and mechanical properties of frozen cement soil structure.In addition to static load,frozen structure will inevitably be subjected to dynamic load such as impact force.Blasting and mechanical Impact load breaking method are common construction methods in frozen body area.By applying high loading strain rate impact load to the structure,the structure can be broken quickly.Therefore,it is of great practical significance to study the Impact dynamic mechanical properties of frozen body.Based on the frozen cement soil engineering as the research background,this paper systematically studies the Impact mechanical properties and failure law of frozen cement soil under high strain rate environment by means of experimental research,numerical analysis and other methods,with the help of split Hopkinson pressure bar(SHPB)test system(1)In this paper,a series of split Hopkinson pressure bar(SHPB)Impact tests of frozen cement soil are carried out with four strain rates,four tempaeratures and three cement contents as variables.The tempactaerature range is-5 ? to-20 ?,the strain rate range is 200 / s to 800 / s,and the cement content is 0% to 10%.The macro crhing characteristics of sampactales under different variables are described,and the stress of sampactales under different variables is analyzed-The change characteristics of strain curve.(2)Under Impactact loading,the dynamic stress-strain curve of frozen cement soil shows obvious strain rate effect and tempactaerature effect,that is,with the increase of loading strain rate,the peak stress and final strain also increase in a positive proportion,and with the decrease of tempactaerature,the peak stress also increases in an inverse proportion,but the final strain will converge,and with the increase of cement content,the peak stress will increase in a negative proportion With the increase of the content,the peak stress also increases in a positive proportion,but the final strain will converge.This paper observed and analyzed the causes of these phenomena.(3)Based on the HJC constitutive model,the numerical simulation of SHPB Impact test of frozen cement soil is carried out by us ing ABAQUS finite element software.The propagation process of loading stress wave in the specimen and member is reproduced through the three-dimensional simulation stress phogram.At the same time,the damage evolution process of the specimen under Impact load is analyzed.The most Impaortant thing is to integrate the macro fracture diagram obtained by numerical simulation with the reconstructed stress phogram.The strain curves are compared with the experimental results.(4)This paper summarizes the calculation method of SHPB energy dissipation of frozen cement soil,analyzes the compaosition of SHPB energy consumpation according to the particularity of frozen cement soil,and studies the influence of freezing tempaerature and impact strain rate on the energy dissipation of frozen cement soil.