Abstract
Coal and rock are often in an environment of hydraulic-mechanical coupling. In order to study the failure mechanism of the coal-rock combined body under the coupling action of hydraulic and mechanical, the RFPA-Flow software was used to analyze the failure mode, strength change law, and acoustic emission change law of the coal-rock combined body with different rock-to-coal height ratios under the combined action of uniaxial load and water pressure. The research results show that the peak strength, residual strength, and stress drop of coal-rock combined body with different rock-to-coal height ratios decrease after water pressure, which reduces the occurrence probability of rock bursts. However, the stress showed a vertical drop phenomenon in the later stage of loading, indicating that the coal-rock combined body still maintains the characteristics of brittle failure after being softened by water, and the roadway may still have rock bursts. The research conclusions can provide a theoretical basis for using water injection measures to prevent rock bursts in deep coal and rock masses.
Highlights
The coal body does not exist alone in the stratum but exists in the form of coal and rock coexistence
This is because the strength and elastic modulus of coal are less than those of rock mass, so the cracks of coal-rock combined body all occur in the coal under the action of external force
The location of the cracks in the coal-rock combined body has nothing to do with whether the coal-rock mass is subjected to water pressure
Summary
The coal body does not exist alone in the stratum but exists in the form of coal and rock coexistence. This paper carries out a numerical experimental study on the failure mechanism of coal-rock combined body under the combined action of hydraulic and mechanical. This has important scientific significance and engineering value for the prediction and prevention of rock burst disasters in deep mines. Yang et al studied the mechanical response and energy partition of coal-rock combinations with different strength ratios through laboratorial uniaxial compression tests and numerical simulation calculations [21]. This paper uses RFPA-Flow software to study the failure mechanism of the coal-rock combined body under hydraulic-mechanical coupling. It is expected to provide a reference for the prevention and control of rock burst disasters in the process of coal resource mining
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