Abstract
As the carrier of force and energy, large-scale breaking or bending of huge-thick conglomerate tends to induce impact ground pressure in stope and tunnel. The stratum movement under huge-thick conglomerate was studied in this paper, which is mainly based on the key stratum theory for ground control. Based on this theory, the huge-thick conglomerate can be regarded as the main key stratum, and stratum movement or the development of grassroots state under huge-thick conglomerate will affect the structure itself, which may induce rock burst in stope and tunnel. The grouting technology is proved to effectively limit the bending settlement of conglomerate, control stress concentration of conglomerate, and improve the structure of the source of rock burst, which is an effective method for the control of huge-thick conglomerate. In this paper, the optimization of grouting filling material ratio is studied by the orthogonal experiments and the results show that the optimization of material ratio is cement: fly ash: gangue 1 : 2.22 : 4.44, concentration 75%. Under such conditions, pumpability and intensity reach the best. Meanwhile, a new technology, called pocket assay grouting technology, is put forward in this paper. It can prevent slurry leakage, protect the environment, and improve the efficiency of slip casting. The application of this technology in Huafeng mine shows that it not only realizes the safe, efficient, and green of coal mine but also provides technical support to control occurrence of rock burst induced by the movement of the huge-thick conglomerate in deep mining.
Highlights
Rock burst is a big problem in mining engineering which brings a huge threat to mine production and people’s life safety [1]. e rock burst induced by overlying rock movement and redistribution of stress field caused by deep mining is one of the most significant deep disasters [2]. e problem has been studied deeply by Guo et al who found that the conglomerate movement may be an internal cause of rock burst [3]
By referring to relevant research experiences and combining with practical experience of coal mine grouting and filling engineering, this grouting and filling material ratio test is divided into three factors: cement content A, ash and gangue ratio B, and backfill concentration C. rough the analysis of these three factors, the orthogonal experiment of three factors and three levels is adopted in this study. e indexes to measure the performance of backfill are backfill pumpability and backfill strength
The cement content of cementing materials is 15%, the fly ash is 1 : 2 for coal gangue, and the backfill concentration is 75%. e experiment measured that the setting time of backfill was 6 h and the collapse degree was 21.5 cm under the condition of the ratio. e stratification degree was 1.8 cm. e bleeding rate was 1.5%. σ28d 4.7 MPa, which fully conforms to the design principle of grouting filling material ratio of Jinchuan company
Summary
Rock burst is a big problem in mining engineering which brings a huge threat to mine production and people’s life safety [1]. e rock burst induced by overlying rock movement and redistribution of stress field caused by deep mining is one of the most significant deep disasters [2]. e problem has been studied deeply by Guo et al who found that the conglomerate movement may be an internal cause of rock burst [3]. In the process of mining, the separation development of superthick conglomerate layers would occur which has an adverse influence on the mining. To tackle this problem, the grouting technology of the separation zone was explored [7]. Separation grouting and filling technology plays a positive role in controlling the movement of giant thick conglomerate layer and controlling the occurrence of rock burst [8]. E grouting technology is that drilling a hole at an appropriate position from the ground and the filling slurry will be injected into the abscission layer space through the hole with high pressure. In China, since the success of the field tests in Laohutai mine, the grouting technology was popularized
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