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

Abstract

Abstract The matrix has a great influence on the mechanical and failure characteristics of the miscellaneous fill. Based on the laboratory medium-sized triaxial test, the confining pressure tests of 100, 200, and 400 kPa were carried out on the miscellaneous fill under three kinds of matrix with block stone content of 30 %, and the influence of the matrix on the mechanical properties of miscellaneous fill was analyzed. A biaxial test with a confining pressure of 200 kPa was carried out on three kinds of matrix miscellaneous fill samples using the particle flow method, and the influence of miscellaneous fill on the failure characteristics was studied. The test results show that the relation curve of the miscellaneous fill (σ1–σ3)∼εa can be considered as a hyperbola. The miscellaneous fill whose matrix is clay and silty soil always shows shear shrinkage. When the confining pressure is 100 kPa, the miscellaneous fill in the sandy soil matrix shows the property of shrinkage first and then dilatancy. When the confining pressure is 200 kPa and 400 kPa, it shows shear shrinkage. Through numerical simulation, it is found that when the matrix is clay, the shear zone is obvious and the shear failure surface is stable. When the matrix is silty soil, the contact cracks become thinner and the shear bands increase. When the matrix is sandy soil, compared with clay matrix, the overall crack is finer and the shear fracture surface is irregularly distributed.