Investigation of particle fragmentation and mechanical response of carbonaceous mudstone under percussive and triaxial compression conditions
To investigate the particle crushing behaviour and mechanical properties of carbonaceous mudstone,the triaxial shear tests on teh fragmentation degree of carbonaceous mudstone with different coarse grain mass fractions were carried out under the best compaction condition,the influence of stone mass fraction on the particle size gradation and mechanical properties of carbonaceous mudstone were analyzed,and the relationship between the particle crushing of carbonaceous mudstone and the surrounding pressure and coarse grain mass fraction was clarified.The results show that the water sensitivity of carbonaceous mudstone is much greater than that of the soil-stone mixture of hard rock,the compaction curve is steeper,and compaction state is the best when the coarse grain mass fraction is 60%.With the increase of coarse grain mass fraction,the shear strength of carbonaceous mudstone shows a trend of first increasing and then decreasing.When the coarse grain mass fraction is 60%,the cohesive force reaches the maximum,and the internal friction is negatively related to the coarse grain mass fraction.When the coarse grain mass fraction is low,the shear strength of the carbonaceous mudstone is mainly provided by the cohesive force of the fine grains and the occlusal force of the coarse and fine grains,and the coarse grains are less broken.With the increase of the coarse grain mass fraction,the broken grains in the specimen are more obvious,and the internal friction is increased by the redistribution and occlusion of the grains.The shear strength is provided by the coarse grain fragmentation and the coarse grain-fine grain occlusion,and the cohesive force of the fine grains is smaller.The relative fragmentation rate of carbonaceous mudstone increases with the increase of surrounding pressure and coarse grain mass fraction,and there is a non-linear relationship between the relative fragmentation rate and coarse grain mass fraction and surrounding pressure.
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