There usually exist irregular and multi-scale cracks or pores in rock, and the seepage channels generated by the cracks or pores probably have scale effects. In this paper, the scale effect on gas permeability is studied by carrying out gas permeability tests of granite and sandstone specimens with different heights. The test results indicate that: (1) The decrease in specimen height has no significant effect on the dry density of both granite and sandstone; However, the decrease in specimen height leads to a decrease in porosity. (2) The permeability of intact granite is found to be homogeneous along the direction of specimen height, while the intact granite may have a certain amount of vertically connected seepage channels with different lengths, which lead to the variation of permeability when the specimen height is reduced. (3) The distribution of seepage paths within the sandstone is found to be inhomogeneous even at the indoor-test scale, and thereby the permeability of sandstone is influenced by the specimen height. (4) The permeability of the excavation-damaged zone in granite formed by tunnel boring machine (TBM) excavation is slightly increased and is also found to be inhomogeneous. The above conclusions demonstrate that the change of specimen height at the indoor-test scale will change the permeability of rocks.
Zhang Dachuan
,
Liu Jian
,
Wang Chunping
,
Chen Liang
,
Wang Ju
. Experimental Study on the Influence of Rock Sample Height on Gas Permeability[J]. Chinese Journal of Underground Space and Engineering, 2025
, 21(S2)
: 690
-699
.
DOI: 10.20174/j.JUSE.2025.S2.19
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