Influence of Macro-Micro Parameters of Rock Block on Mechanical Properties of Rock Mass in Caving Zone
In order to study the influence of macro-micro parameters of rock block on the mechanical properties of rock mass in caving zone,field experiment method was used to carry out the confined compression test on the core samples in goaf.Based on the experimental results,PFC3D numerical simulation method was used to simulate the compression deformation characteristics of caving zone under engineering scale,the influences of model size,rock block size,crushing expansion coefficient and micro-mechanical parameters on the mechanical properties of rock mass in caving zone were analyzed.The linear stress-strain constitutive relation of caving zone was obtained by dimensional analysis.The results show that the loading curve of the core samples change approximately linearly,and the slope of the stress-strain curve increases with the increase of the total length of the core.The compression of caving zone increases with the increase of diameter-height ratio and crushing expansion coefficient,and decreases with the increase of block size and effective modulus.When the ratio of the diameter to the height of the model is greater than 3∶1,the influence of the model size on the compression deformation characteristics of the caving zone is significantly reduced.When the rock block size is greater than 1.3 m,the compressive deformation curve of the caving zone changes from exponential increase to linear increase.When the crushing expansion coefficient is lower than 2.0,the compression deformation curve of the caving zone changes linearly.When it is higher than 2.0,the stress-strain curve changes exponentially,and the pore compaction characteristics of the caving zone gradually increase.
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