To investigate the effect of the radius of the spherical heads of the indenter on the results of a point load test, this study uses a discrete element model based on the flat joint contact for numerical simulation. Results show that the discrete element model based on the flat joint model can accurately describe the damage process and size effects of rocks under point loads. Damage of rock samples under the loading of different radii of the indenter can be characterized as vertical splitting damage, and the larger the radius of the indenter is, the larger the damage area. Values of the point load strength of rock samples increase with increasing the radius of the indenter and obey a power function relationship. The results of this study provide a theoretical basis for the selection of the spherical heads of indenters in point load tests and tool design for mechanical rock breaking.
王智1，欧阳义平1，杨启1
,
2
. Numerical Simulation on Effect of Indenter Radius During Point Load Test[J]. Journal of Shanghai Jiaotong University(Science), 2024
, 29(5)
: 909
-918
.
DOI: 10.1007/s12204-023-2583-1
[1] LIU Q S, ZHAO Y F, ZHANG X P, et al. Study and discussion on point load test for evaluating rock strength of TBM tunnel constructed in limestone [J]. Rock and Soil Mechanics, 2018, 39(3): 977-984 (in Chinese).
[2] PANEK L A, FANNON T A. Size and shape effects in point load tests of irregular rock fragments [J]. Rock Mechanics and Rock Engineering, 1992, 25: 109-140.
[3] CHAU K T, WEI X X. A new analytic solution for the diametral point load strength test on finite solid circular cylinders [J]. International Journal of Solids and Structures, 2001, 38(9):1459-1481.
[4] MASOUMI H, SAYDAM S, HAGAN P C. Unified sizeeffect law for intact rock [J]. International Journal of Geomechanics, 2016, 16(2): 04015054.
[5] CHEN P Y, KONG Y, YU H M. Research on the calibration method of microparameters of a uniaxial compression PFC2D model for rock [J]. Chinese Journal of Underground Space and Engineering, 2018, 14(5):1240-1249 (in Chinese).
[6] POTYONDY D O. A flat-jointed bonded-particle material for hard rock [C]//46th U.S. Rock Mechanics/Geomechanics Symposium. Chicago: American Rock Mechanics Association, 2012: ARMA-2012-501.
[7] DING X B, ZHANG L Y. A new contact model to improve the simulated ratio of unconfined compressive strength to tensile strength in bonded particle models [J]. International Journal of Rock Mechanics and Mining Sciences, 2014, 69: 111-119.
[8] DU G S, CHEN S J, GAO Z W. Estimation of uniaxial strength of iron ore by point load test based on PFC [J]. China Mining Magazine, 2019, 28(S2): 406-410 (in Chinese).
[9] BAHAADDINI M, SHEIKHPOURKHANI A M, MANSOURI H. Flat-joint model to reproduce the mehanical behaviour of intact rocks [J]. European Journal of Environmental and Civil Engineering, 2021, 25(8): 1427-1448.
[10] OUYANG Q A. Laboratory experiments and distinct element method research on quasi-static and dynamic mechanical properties of ice [D]. Tianjin: Tianjin University, 2017 (in Chinese).
[11] POULSEN B A, ADHIKARY D P. A numerical study of the scale effect in coal strength [J]. International Journal of Rock Mechanics and Mining Sciences, 2013,63: 62-71.
[12] OUYANG Y P, YANG Q, CHEN X Q. Bonded-particle model with nonlinear elastic tensile stiffness for rocklike materials [J]. Applied Sciences, 2017, 7(7): 686.
[13] XU J M, HUANG D Y, ZHU H C. Relations between macro- and meso-scopic mechanical parameters of granite based on actual distributions of mesocompositions [J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 35(S1): 2635-2643 (in Chinese).
[14] FU Z L. Experiment course on rock mechanics [M]. Beijing: Chemical Industry Press, 2011 (in Chinese).
