AE Characteristics of Rockburst Tendency for Granite Influenced by Water Under Uniaxial Loading

Abstract

In deep mining, granite is stored with high energy duing to its structural integrity and brittleness. Rock bursts usually occur because stress changes and mining disturbances during mining, which seriously threaten safe production. Focusing on the factor -waterwhich may reduce the brittleness and rockburst tendency of granite, this work discussed the brittleness index and AE characteristics of dry and saturated water granite samples under uniaxial loading. The results show that the peak strength and elastic modulus of the saturated water granite are reduced. The damage degree of the water sample is larger than that of the dry sample, and the brittle failure is significantly reduced. The cumulative number of acoustic emission (AE) events in saturated water granite is significantly reduced compared to the dry sample, which is a decrease of 31.5%. However, AE event rate is higher than that of dry granite in the late loading period; AE quiet period of saturated water granite lasts longer and is more obvious than that of dry granite. Dry granite stores and releases more energy during the whole loading process, and the proportion of high energy level AE events in the later stage of loading is higher. The b value of the two samples show a downward trend with fluctuation in the critical state of fracture and a jump increases at the moment of instability. The decrease of b values of dry granite is larger than that of saturated water granite. Results suggest that the decline of AE b value of granite can be taken as the precursor of rock burst, and water can significantly reduce the rockburst tendency of granite.

Research on Maximum Likelihood b Value and Confidence Limits Estimation in Doubly Truncated Apparent Frequency–Amplitude Distribution in Rock Acoustic Emission Tests

“…The composition of the mineral particles of granite is complex; there are obvious cracks between the particles, which are prone to large-scale block slippage under the action of external loads, so the b value of granite is smaller than that of marble and red sandstone. The above analysis and the b-value estimation results are consistent with other studies; the brittleness of granite is greater than that of marble and red sandstone in the tests, and more high-energy-level AE events are generated during the failure process [46][47][48][49]. Additionally, although the calcite particles that make up limestone are more tightly coupled than red sandstone, there are more large-scale bedding planes inside, resulting in more large-scale damage, resulting in the smallest b value.…”

Design Method for Specific Charge in Deep Mining considering Influence of In Situ Stress

“…A lack of systematic study on improving blasting efficiency has existed in the past, leading to a poor ore dilution rate and loss rate. At the same time, the strong brittleness of rock mass frequently leads to the phenomenon of rockburst [27,28].…”

Experimental Study on Fracturing Characteristics of Double-Hole Blasting Under Static Stresses

“…The uniaxial static load could change the optimal load and the critical buried depth of charge. The granitic lithology with a complete deep structure has high energy storage capacity (Wang et al, 2019;Zhang et al, 2020). The influence of the confining pressure and ratio of horizontal pressure to vertical pressure on blasting rock fracture was studied through experiments.…”