Load transfer mechanism of limestone under uniaxial compression using the particle flow method

The load transfer mechanism in rock is of great importance for investigating the engineering properties of rock materials. The particle flow method was used to simulate the load transfer mechanism in this study. Taking a limestone sample with the size of 50 mm× 50 mm as an example, the particles of rock were characterized with circular discs and the parallel bond model was adopted to simulate the linkages among the particles. Results of the uniaxial compression test indicate that the elastic modulus, peak stress and Poissons ratio of the specimen are 44.24 GPa, 101.05 MPa and 0.267, respectively. The force chains larger than the mean contact force were defined as the strong force chains, and the distributions of the strong force chains in the sample were thereafter obtained under the uniaxial compression conditions. The local microparameters, such as porosity and coordination number, were also examined. The distributions of the contact forces in the sample under various friction coefficients after reaching peak stress were taken into account. The results show that the strong contact forces were 19.8 percentages of all forces but took 75 percentages of the strain energy in the sample; the ratios of the normal to shear contact forces were larger than 3.5, the normal contact forces dominated all of the stresses in the limestone; the local porosity of the sample after failure varied quite litttle with a decrease of only 0.002. This paper may be used as references in investigating the microscopic mechanism of the deformation and failure of rock materials under external load.