Study on the Influence of Matrix on Mechanical and Failure Properties of Miscellaneous Fill

Abstract Urban miscellaneous fill is a particular type of heterogeneous soil with complex structure and various components, and its mechanical and failure properties are related to matrix characteristics. Using the laboratory medium-sized triaxial test, we carried out 100, 200, and 400 kPa confining pressure tests on clay, silt and sand matrix miscellaneous fills with the stone content of 30%, respectively, and analyzed the influence of the matrix on the mechanical properties of the miscellaneous fill. The results reveal that the miscellaneous fill (σ1-σ3)～εa the relation curve can be considered as hyperbola. The miscellaneous fill with clay and silt matrix always shows shear shrinkage. When the confining pressure is 100kPa, the miscellaneous fill with sand matrix shows shear shrinkage first and then shear dilatancy. When the confining pressure is 200 and 400kPa, it shows shear shrinkage. Furthermore，We used the particle flow method to carry out the biaxial test of three kinds of matrix miscellaneous fill under confining pressure of 200kPa, and analyzed the influence of miscellaneous fill on the failure properties. The test result shows that in the initial loading stage, the specimen is dominated by compaction deformation. As the load increases, the deformation of the specimen is dominated by compaction and particle rotation. When the matrix is clay, the shear zone is obvious and the shear failure surface is stable. When the matrix is silt, the contact cracks become thinner and the shear bands increase. When the matrix is sand, compared with clay matrix, the overall crack is finer and the shear fracture surface is irregularly distributed. Relevant research results can provide theoretical guidance for urban miscellaneous fill landfill.