The Study On Soil Dynamic Triaxial Test With The Vibration Of High-Speed Railway Train

With the growing demand for transport vehicle speed, high-speed railway came into being. It can be more effective in boosting economic and social development. At present, the total mileage of high-speed railway are among the first in the world both which has been built and under construction. And the safety performance of the high-speed railway system has attracted a lot of attention. This is not only an important part of Train-Track-Subgrade coupling study, but also is a focus on research of soil and rock properties under high-speed railway train load. When the railway line through the area of soil, it will applied vibrating load on the soil. Therefore, the study on the dynamic properties of soil under the high speed railway train vibration has important theoretical significance and practical value. Soil is a three-phase body with solid, liquid and gas exist at the same time. Its nature is relatively complex. In different dynamic stress-strain combination, it will show different mechanical state. General soil dynamic properties indoor test methods have resonance column and dynamic triaxial test. When the soil test dynamic strain amplitude≤10-4, using the resonant column test; if the soil sample test of dynamic strain amplitude more than10-4, can ues dynamic triaxial test method.The soil samples were taken from DK36+515of Chengdu-Dujiangyan high-speed railway. The dynamic properties parameters were measured by dynamic triaxial test. In this paper, the main research contents include:1. Some basic physical parameters of the soil sample can be determined by soil test. And the soil test show that:the natural moisture content of the soil sample is20%, natural density value is2.1g/cm3, plastic limit of20.6%and liquid limit is39.5%.Then make the soil sample into standard undisturbed sample by sample preparation device.2. This paper considers the important factors that impact soil dynamic triaxial test are axial load, vibration frequency and confining pressure. Simulate the special vibration of high-speed railway train indoors, then design7different test control conditions by changing combination of the three important factors. Finally, analysis the key data that recorded by the test instrument data acquisition system. 3. Based on the relation curves between residual cumulative strain and vibration times, it can be found that with vibration times increasing, soil strain raise. And non-destruction model soil strain will tend towards stability by a large number of vibration times. Besides. it’s positive correlation between dynamic stress ratio and soil strain value and its development rate. Meanwhile, under the same vibration times, the greater the vibration frequency, the greater the value of strain generated.4. According to the test data, the relationship of pore pressure and vibration times can be described is positive correlation. The pore pressure increase with vibration times is not monotonic, but undulate. In addition, in a certain vibration times or before destruction. pore pressure will appear a peak value. After that, the pore pressure would develop slowly or tend to be stable.5. Based on the testing data, the dynamic shear modulus and initial dynamic shear modulus were calculated by the mathematical formula. Then the influence factors of dynamic shear modulus and dynamic shear modulus ratio were analyzed in this paper.