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| DIMENSIONAL ANALYSIS OF EFFECTS OF MICROSCOPIC PARAMETERS ON MACROSCOPIC PARAMETERS FOR CLUMP PARALLEL-BOND MODEL |
| XIA Ming，ZHAO Chongbin |
| (Computational Geosciences Research Centre，Central South University，Changsha，Hunan 410083，China) |
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Abstract Based on the new and conventional loading procedures，the rock mechanical behaviors are simulated through using the clump parallel-bond model(CPBM) to conduct a series of numerical experiments at the specimen scale. Meanwhile，using the new developed loading procedure，the effects of loading rate and frozen period on the stress-strain response of a particle model are investigated. Furthermore，the effects of microscopic parameters on macroscopic parameters of the specimen，which is modeled by the CPBM，are studied using the dimensional analysis. Certain semi-quantification relationships between macroscopic parameters，such as the elastic modulus，Poisson′s ratio，uniaxial compressive strength(UCS) and tensile strength(TS)，and microscopic parameters of the specimen are established. The related numerical results have demonstrated that：(1) When using the conventional loading procedure，the produced stress-strain curve is incorrect；the elastic modulus，UCS and TS are overestimated；while the post-peak mechanical response of brittle rock with brittle behaviour cannot be reproduced. The failure patterns of the specimens under different loading procedures are totally different. (2) When using the new loading procedure，the CPBM can be used to reproduce a high ratio of the uniaxial compressive strength to tensile strength(UCS/TS＞10). The strength is independent on the loading rate in the quasi-static range，which is consistent with the experimental results. Meanwhile，the effect of loading rate is mainly concentrated on the post-peak range of the stress-strain curves. (3) Elastic modulus is mainly determined by the particle contact modulus and contact stiffness ratio. Poisson′s ratio is mainly determined by the contact stiffness ratio. Compared with the conventional parallel-bond model，in order to obtain the same Poisson?s ratio in the calibration，a larger value of the contact stiffness ratio should be chosen in the CPBM. The UCS and TS can be scaled by either the parallel-bond shear strength or the parallel-bond normal strength，depending on the ratio of the two quantities. The UCS is also dependent on the number of particles in one clump.
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Received: 13 March 2013
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2014, Vol. 33 
