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| Correlation of the geometrical and mechanical size effects of fractured rock masses |
| CHEN Qingfa1，2，ZHENG Wenshi1，2，NIU Wenjing2，YIN Tingchang1，2，FAN Qiuyan1 |
| (1. College of Resource，Environment and Materials，Guangxi University，Nanning，Guangxi 530004，China；2. State Key
Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China) |
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Abstract Based on the blockiness index，this study attempts to unravel the correlation of the geometrical and mechanical size effects of fractured rock masses from the perspective of the spatial structures of rock masses. First of all，a total of 35 types of multi-scale three-dimensional fracture networks of rock masses，possessing various combinations of different persistence and spacing of discontinuities，were established by GeneralBlock. Using the improved blockiness evaluation method developed by the authors，the blockiness values of the rock masses with different scales were measured，and the geometrical representative element volumes of rock masses(i.e.，geometrical REV) were obtained. Then，multi-scale discrete fractures networks of rock masses were built by the combined use of GeneralBlock and 3DEC，the change law of the rock mass compressive strength and elasticity modulus with rock mass sizes was discussed，and the mechanical representative element volumes(i.e.，mechanical REV) were determined. Finally，the geometrical and mechanical REVs were compared，and then the correlation of the geometrical and mechanical size effects of fractured rock masses was evaluated. The results show that the geometrical REV is lesser than the mechanical REV，and the mechanical size effect is induced by the geometrical size effect；with the increase in the scales of rock masses，the geometrical parameters tend to be stable，and then the mechanical parameters are the same(i.e.，the geometrical REV is achieved earlier than the mechanical REV).
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2019, Vol. 38 
