Research On Distribution Of Vertical Stress In Soil Under Vibratory Drum

In our country highways are semi-rigid with strong sub-grade and thin pavement. So thestrength of the sub-grade determines the bearing capacity and service life of the highway.Lacking strength and low compaction degree of sub-grade will lead to fatal damage to theroad, such as surface subsidence which is unable to repair completely. Therefore thecompaction of the sub-grade soil is the key to roads’ high bearing capacity and long servicelife.Single drum vibratory rollers, as the dominant soil compaction equipment, make the soilclose-grained by the drum’s module weight and vibration. In this paper full hydrostatic singledrum vibratory rollers are tested and researched. According to the performance parameterstest of the prototype,"vibration drum-soil" of Abaqus finite element model is built. Then thevertical stress distribution in the soil under the vibrating drum was studied by theexperimental research and simulation analysis methods.This article first analyzes the composition and compaction mechanism of soil withintroduction to the different compaction methods and their theoretical basis. Then theelasticity, viscosity and plasticity of soil constitutive relation are analyzed.Then the best water content and maximum dry density of the soil are obtained byexperimental test. It tested the relationship between the soil’s elastic modulus, angle ofinternal friction and cohesion with the soil’s dry density. The rollers’ start up characteristics isanalyzed with low frequency-high amplitude and high frequency-low amplitude two kinds ofworking condition. Then according to the test result of vertical stress amplitude in the soilsunder vibrating drum, it got the conclusion that the vertical stress consists of the dynamicstress and static stress of two parts. Besides the static stress is greater than the dynamic stressand dynamic stress’s frequency is the same as the drum’s vibration frequency. After that thevertical stress amplitude in the soil with soil depth changing rules are analyzed.At last, the paper analyzes the vertical soil stress’s distribution in drum’s width directionwhen the drum is not vibrating and vibrating according to the model of Abaqus simulationresults. It founded that the soil vertical stress is maximum below the edge of the drum. Itanalyzed the soil vertical stress distribution when soil (10cm) stress reaches a maximum,founded the stress transmission lag effect caused by soil’s damping. The influence of thedrum’s vibration frequency to the vertical stress amplitude and its decay with the soil depth isanalyzed. The frequency responses of the different depth’s soil are stated. Then it analyzed the relation between the nominal amplitude and vertical stress amplitude. All of the resultsprovide a data basis for choosing the vibration parameters according to actual requirements.