Abstract
Rock burst is one of the disaster accidents that can easily happen in rock cavern engineering. At present, one of the most commonly used methods to control rock burst is borehole pressure relief technology. In this paper, the influence of drilling layout schemes on the pressure relief effect of surrounding rock mass is systematically studied. The research results show that the strength reduction degree, AE evolution characteristics, failure modes of rock samples with different borehole positions, boreholes spacing, boreholes dip angles, and boreholes layout forms are different. The strength reduction degree of rock sample with an inclined arrangement form is the largest, followed by the arrangement form being up three-flower layout or down three-flower layout. Using the inclined layout and three-flower layout can achieve better pressure relief effect of the surrounding rock mass. The research results are beneficial to the rock burst of surrounding rock of the cavern. The acoustic emission can effectively monitor the stability of the surrounding rock of the cavern. However, the threshold value and the occurrence time of the acoustic emission of the cavern instability changed after the cavern surrounding rock is drilled holes. If the borehole is arranged at the surrounding rock mass, the occurrence time of the cavern instability may be advanced.
Highlights
With the rapid development of economy and technology as well as the increase of population, the underground rock cavern engineering has made great progress
In order to systematically explore the influence of drilling layout schemes on the pressure relief effect of rock burst prone surrounding rock mass, this paper considered the following four simulation schemes according to the actual drilling characteristics. e size of these models is 50 mm × 100 mm and the parameters of them is the same as in Table 1. e process of establish the models is as follows: (1) establish complete rock models, which have the same particle distribution form and the same mechanical properties; (2) according to the test schemes, delete some particles to simulation drilling holes, and all the drilling holes have the same diameter of 6 mm
The corresponding occurrence time shows a trend of increase firstly and decrease, which are consistent with the change of the uniaxial compressive strength (UCS). is shows that the acoustic emission can effectively monitor the stability of the surrounding rock of the caverns
Summary
With the rapid development of economy and technology as well as the increase of population, the underground rock cavern engineering has made great progress. In the aspect of drilling pressure relief technology research, Liu et al [3] used laboratory test, numerical simulation, and theoretical method and analyzed the mechanism of boreholes to prevent rockburst, and the research results show that the borehole spacing is a function of borehole diameter, thickness of coal seam, increasing overflow coefficient, and safety increasing variables and is related to increasing overflow coefficient and borehole diameter. Yi et al [6] used FLAC numerical simulation to analyze the pressure relief effect of large-diameter drilling in soft and hard coal seam; the research results show that the pressure relief effect of drilling in soft rock is better than that in hard rock. Ese researches are of great significance to alleviate the rock burst risk of surrounding rock of cavern; there are few systematic researches on the influence of drilling layout schemes on the pressure relief effect. The rock models of different drilling layout schemes are established by means of particle flow code (PFC); secondly, the influences of different borehole positions, boreholes spacing, boreholes dip angles, and boreholes layout forms on the strength reduction characteristics, acoustic emission evolution characteristics, and failure modes of rock samples are analyzed. e research results are beneficial to the rock burst of surrounding rock of the cavern
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