Abstract
Particle size is an important factor affecting the Thermal-Hydraulic-Mechanical (THM) coupling behavior of graveled rock mass, especially for the shear mechanical properties. In this study, three groups of the particle size range and nine particle grading samples are designed for a large-scale direct shear test. The relationships between shear stress and shear displacement, shear strength, stress ratio, shear strength parameters, and particle breakage of pebble gravel are analyzed. The influence of particle size range and grade on the strength and particle breakage of gravel material is discussed. Results show evident particle breakage in the process of direct shear, and the degree of fragmentation is controlled by the normal load and the particle size distribution of the sample. The shear strength of the sample is no longer applicable to Mohr-Coulomb strength theory because of particle breakage that is more in line with the power function relationship. Shear strength of pebble gravel material has scale effect, and a corresponding relationship model between friction coefficient f of material and characteristic particle size of the sample is proposed.
Highlights
Research on the mechanical properties of intact rock, including compressive strength, shear strength, and tensile strength, has achieved many results through large number of tests in recent years [1,2,3,4,5,6,7,8]
The influence of particle size on the strength of pebble gravel materials is explored through a large-scale direct shear test
This study provides a method for the shear strength characteristic research of pebble gravel material, and the proposed model can be used to predict the shear strength of the material with different particle gradation
Summary
Research on the mechanical properties of intact rock, including compressive strength, shear strength, and tensile strength, has achieved many results through large number of tests in recent years [1,2,3,4,5,6,7,8]. Many scholars attempt to build particle grading samples in accordance with the requirements of the indoor test by a certain scale method and calculate the mechanical parameters of the original graded gravel. The influence of particle size on the strength of pebble gravel materials is explored through a large-scale direct shear test. The relationship model between the shear strength parameters and the characteristic particle size of the sample is established, and the particle crushing characteristics of the material are studied. This study provides a method for the shear strength characteristic research of pebble gravel material, and the proposed model can be used to predict the shear strength of the material with different particle gradation
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