Study On Deformation Characteristics Of Soil In Jiaozuo Area Under Traffic Load

With the rapid development of China's economic construction,the development speed of urban rail transit construction is accelerating,and the engineering geological disasters caused by traffic load have been paid more and more attention.At present,the dynamic characteristics of soil in Jiaozuo area have not been studied,so it is necessary to study the dynamic characteristics of soil under traffic load.In this paper,dynamic characteristics of soil in Jiaozuo area are studied by the method of dynamic three axis test,resonance column test and FLAC^3Dsoftware simulation.The purpose of this study is to reveal the deformation law and influence factors of soil under the action of traffic load,and to provide the number of dynamic parameters needed for the evaluation of ground engineering vibration.Suggestions.The main research contents and conclusions are as follows:(1)The cyclic loading tests of 41 groups of original samples were carried out by the dynamic three axis instrument,and the deformation characteristics of soil under the action of traffic load were studied.It was concluded that the dynamic stress had a great influence on the deformation,and there was a significant critical dynamic stress before and after the failure of the specimen.The different vibration waves have obvious differences in the deformation of the soil mass,and the semi sinusoidal loading is more consistent with the real vibration state of the traffic load.The effect of vibration frequency on soil deformation has a critical vibration frequency,and the smaller the applied vibration frequency is,the smaller the deformation is.The increase of confining pressure and consolidation will increase the strength of the soil,but the confining pressure will have a greater impact.In the experiment,the positive and negative static stress and the half sine wave are applied together to make the stress state of the soil different from the simple harmonic wave.When the partial stress is zero or positive,it only produces the pressure strain.The partial stress is negative when the stress is negative.The greater the partial stress is,the greater the deformation is,but it is less than the effect of thedynamic stress on the deformation.(2)The dynamic parameters of 24 borehole samples were tested by the resonance column test.The test values were compared with the typical values of the dynamic shear modulus ratio and the dynamic damping ratio given by the"94 standard value"and"Yuan Xiaoming recommended value",and the dynamic shear modulus ratio increased with the depth,and the dynamic damping ratio was with the depth.The dynamic shear modulus ratio is between the"94 standard value"and"yuan Xiao Ming recommended value",and the dynamic damping ratio"statistical value"is smaller than the"94standard value"and"Yuan Xiaoming recommended value",and the dynamic damping ratio of the"statistical value"is less than the"standard value"and"the recommended value".The"statistical value"is used in the dynamic evaluation.(3)The FLAC^3Dsoftware is used to simulate the effective dynamic stress,horizontal acceleration and vertical displacement of the natural site under the traffic load.In the simulation,the simple harmonic forms of different combinations of the dynamic stress amplitude value of?_d=8kpa,15kpa and the vibration frequency f=5Hz,2.5Hz and 1Hz are introduced.The results show that the vertical displacement of the center is the largest,and the displacement decreases with the increase of the distance between the center sides.The dynamic response of the center surface is strongest,and it decreases with the increase of depth.The dynamic stress,horizontal acceleration and vertical displacement are all larger in the same depth soil layer,and the vibration frequency has a great influence on the horizontal acceleration,and has little effect on the effective dynamic stress and the vertical displacement.The effect of vibration frequency on the vertical displacement of soil is related to the natural frequency of the soil layer,and the closer to the natural frequency,the smaller the vertical displacement.In view of the effect of the amplitude and frequency of dynamic stress on the vertical displacement of the soil layer,it is suggested that the influence of the body load on the ground soil should be taken into consideration in the train operation in Jiaozuo,and the speed of the driving should be avoided as far as possible to avoid the natural frequency of the soil.