Strength and Deformation Behavior of Roadbed Aggregate by Large-Diameter Triaxial Test

Graded aggregates are widely used in the roadbed of high-speed railway, and its strength and deformation play a decisive role in determining the long-term service stability of railway. In this paper, aggregates with different gradation were tested by large-diameter triaxial testing apparatus. The influence of some key parameters, such as gradation, compaction degree and loading level on aggregate specimen’s strength and deformation behaviors are discussed based on the test data. The characteristics of particle breakage are presented. Based on experimental results, the graded aggregates which content of more coarse particles, when the compaction degree reach a certain extent, its strength has little relation with its compaction degree, for the graded aggregates which content of less coarse particles, only when the compaction degree is relatively high that can give full play to its strength. The graded aggregates which has a good gradation, resulting in little particle breakage. However, the specimen which has a relatively uniform size, results in more particle breakage. At a certain compaction degree, the amount of particle breakage obvious increase with the increase of confining pressure. It can be found that the volumetric strain caused by particle breakage cannot be neglected in the total volumetric strain of the gravel, especially in the case of relatively high confining pressure, the ratio of 10% can be achieved.