Dynamic Response Properties Of Red Sandstone Soil Under Confined Compression And Cyclic Impact Loadings

Being widely distributed in China,the red sandstone soil is also large found in the topsoil of mountains in southern Jiangxi province.As a widely used form of foundation in the modern geotechnical engineering,the red sandstone soil foundation,in order to meeting the requirement of the engineering,is reinforced by vibration method.But by such method,as well as the disturbance of generated by the incidental load,will bring great impact on the dynamic characteristics of the red sandstone soil.so far,the study on effect generated by such impact load and the amount of energy consumed by the foundation soil is inadequate.using the combined method of experiment and numerical simulation,this paper discussed the dynamic response of confined red sandstone soil under the cycle impact loadings.Conclusions are as follows:(1)With the number of the cycle impacts increasing,the energy absorption value is in an S incremental change.The obtained absorption can be used to squeeze the soil in the gas and liquid and soil particles pore,which makes the soil particles rearrange and the internal structure redistributes,and enhances the red sandstone soil to resist the impact of the outside.The dry density has a great effect on the the energy absorption value of the red sandstone soil.When the pressure is constant,the impact load is positively correlated with energy absorption values.When the impact load is constant,the axial pressure is negatively correlated with the specific energy absorption value.(2)With the increase of impact times,the cumulative energy absorption of red sandstone soil increases constantly,and with the increase of the dry density,the cumulative absorption energy is growing faster,that is to say the curve becomes steep;and the data of the correlation coefficient of total absorption energy is by fitting,which can calculate the cumulative energy absorption of the red sandstone soil in the dry density corresponding to a cycle impact.The same analysis method is used to calculate the red sandstone soil under different axial pressure and shock loads.The total absorption can get the degree of soil reinforcement under cycle impact load,which provides the relevant data to engineering practice.(3)The dynamic compressive strength and average strain rate was negatively correlated,and with the increase of average strain rate,both the increase of axial pressure or impact load,the dynamic compressive strength decrease and gradually closer.In the cyclic impact process,with the increase of impact times,the peak stress increases gradually in an S incremental type curve,while the average strain rate gradually decreases in an S decline curve.(4)Using the stress and displacement size with the finite element program output,according to the relationship between the amount of energy and soil sample volume changes of red sandstone,through the manual programming points,this paper obtains a result that under the impact load,the size of the energy absorption is close to the test results.For further research,the dynamic characteristics the laws of energy transmission and absorpti on of red sandstone soil under a medium to large strain rate can be simulated by finite element program.This paper gets the mechanical performance parameters of the red sandstone soil under the cycle impact loads,which enriches the energy propagation theory of the red sandstone soil under the dynamic load.The law of energy dissipation of the red sandstone soil is analyzed to pave the way for the further research on the reinforcement of the red sandstone soil under the cycle impact load.