Study on the Mechanisms of Rock Mass Watering for Rockburst Prevention in Phosphorite Mines from Laboratory Results

Abstract

Owing to the continuous increase in mining depth, Yichang phosphorite mines in China have entered the field of deep mining. The frequency of rockburst disasters is increasing. In situ experience indicates that the practice of spraying water onto a working face after blasting is an effective method of rockburst prevention. In order to investigate the underlying mechanisms of rockburst prevention by watering in phosphorite mines, a series of uniaxial compression laboratory experiments was carried on phosphorite samples under dry and water-saturated conditions with an acoustic emission (AE) monitoring system. A high-speed camera was used to record the failure process and pattern of a given rock sample prior to rockburst. The effects of water on the mechanical properties and fracturing characteristics of phosphorite failure were determined. Experimental results indicate that water reduces the uniaxial compressive strength and Young’s modulus. Saturated phosphorite causes more small fragments after it fractures. A Gaussian mixture model (GMM) clustering algorithm was utilized to analyze the crack propagation patterns of rock samples during the entire process. It was determined that during the unstable crack propagation phase, the presence of water makes the shear characteristics become more obvious. Water reduces releasable strain energy which is consumed by internal damage and plastic deformation of the rock sample. Moreover, the mechanism of watering for rockburst prevention is discussed from both macro and micro perspectives. The primary reasons for this are the transfer of stress concentration zones and stress-releasing effects via microcrack propagation on the working face.