Subgrade Compaction Test And Analysis Additional Dynamic Stress In Field Test

This dissertation dicuss the mechanism of vibratory compaction by the research of relevant documents of vibratory compaction technology. We made two experiments:a model of soil filling test is made by vibration plates indoor and dynamic vibrational stress test in field compaction on gaozi site of Beijing-Shanghai high-speed railway. Though data processing and analysis, conclusions are made below.(1)When the vibratory roller is rolling on the bridge back, its working condition can change the distribution of dynamic stress of bridge back. The dynamic stress decrease when the distance between the vibration wheel and bridge back increase.when using transverse rolling construction, the sphere of influence is mainly the distance between lateral margin of the vibration wheel and bridge back,that is about 0-1.5m.while using Longitudinal rolling, the sphere of influence is mainly the distance between lateral margin of the vibration wheel and bridge back,that is below lm.(2)The different working conditions of vibratory roller have a strong influence on the distribution of dynamic stress of subgrade. The maximum dynamic stress under the condition of YZ18JC strong vibration is about 1.8 times that under static pressure. In the compaction process, under the vibration wheel is the largest distribution of dynamic stress. The sphere of influence of the vibration wheel on the vertical orientation is 0-1.2m, on the horizontal orientation is 0.5m.(3)When the vibration plates is making a vibration compaction on the bridge back, the maximum dynamic stress the bridge back bear (H=0.3m,the dynamic stress is 32.5 kPa) is as much as that of the YZ18JC vibratory roller test value, when the vibration plates is making a vibration compaction on the subgrade, the maximum dynamic stress under 0.3m can reach 106.06 kPa, is about a third of the value under the condition of weak vibration. The compaction paving thickness can't be too large, small vibration plates can compact bedding packing (graded broken stone) effectively.By the control of the filling layer thickness 20cm and the optimum water content 5.27%, the compaction factor will be greater than 0.97,the maximum dry density will reach 2.42 g/cms3,and the foundation coefficient will be 278-384 MPa/m. The Compaction effect totally reach the specified value on the bedding packing compaction of the Design of high-speed railway.(4)Simplify the force vibratory roller to the foundation to a line load and use Boussinesq.J to calculate the additional stress. Compare the calculated value with the measured value, and make a curve match. A conclusion is made; When the vibration roller static passes on the subgrade, the dynamic stress is about Logarithmic attenuation. The distribution of dynamic stress of subgrade match the Boussinesq calculate results. When the vibration roller vibratory passes on the subgrade. as ignoring the stiffness and damping of the subgrade, the measured value is about 75% of the calculate results, the dynamic stress's attenuation match the calculated value.