Study on the Instability Characteristics and Bolt Support in Deep Mining Roadways Based on the Surrounding Rock Stability Index: Example of Pansan Coal Mine

Abstract

In view of the influence of mining stress on the stability of the surrounding rock of inclined roof mining roadways in deep mines, the surrounding rock stability index is defined and solved based on the rock strength criterion and the stress distribution. The mining roadway of the 17102(3) working face of the Pansan Coal Mine is used as the engineering background and example. The surrounding rock’ stabilities under the conditions of no support and bolt support are analyzed according to the surrounding rock’s stability index and the deformation data. The results show that the areas of low wall and high wall instability are 1.68 m2 and 2.12 m2, respectively, and the low wall is more stable than the high wall; the areas of the roof and floor instability are 0.33 m2 and 0.35 m2, respectively, and the roof and floor are more stable than the two sides. During mining, the area of instability greatly increases at first, then decreases to 0, and reaches a maximum value at the peak of the abutment pressure. The stability of the surrounding rock decreases first and then increases. Compared with the end anchoring bolt support, the full-length anchoring bolt support reduces the area of instability to a greater extent, and the full-length anchoring bolt support effect is better. The surrounding rock in the end anchoring zone and the full-length anchoring zone began to deform significantly at 200 m and 150 m from the working face, respectively. This indicates that the control effect of the full-length anchoring bolt support is better and verifies the rationality of the surrounding rock stability index to describe the instability characteristics. This research method can provide a theoretical reference for analysis of the stability characteristics and support design of different cross-section roadways.

Influence of anchorage length and pretension on the working resistance of rock bolt based on its tensile characteristics

“…Wang et al (2018) found that when the anchorage length of the bolt is fixed, the effective compressive stress area in the surrounding rock of the non-anchored portion increases with the increase of the pretension. Chang et al (2020) defined the surrounding rock stability index and then studied the stability of the surrounding rock with different anchorage lengths. They found that the full-length anchoring bolt support reduces the area of instability to a greater extent, compared to the end-anchoring bolt support.…”

Study on the Stability Principle of Mechanical Structure of Roadway with Composite Roof

“…However, so far, the proportion of bolt support is low (less than 30%), and for complex and difficult roadways, such as in Guizhou mining area, for a large number of complex roof conditions, shed support was used in the roadway only basically. Practice has proved that as passive support, shed support cannot effectively restrain the large deformation of composite roof, the support and maintenance costs are high, and roof fall accidents occur frequently, which seriously threaten the safety production of the mine [12][13][14][15][16]. Therefore, to carry out research on the stability mechanism of roadway surrounding rock under the condition of composite roof, a scientific and reasonable mechanical structure model was established, and the adaptability of bolt support technology was theoretically explored under this condition, which is a useful attempt to promote the development of roadway excavation technology, with important theoretical value and practical significance.…”

Study on the Influence of Anchorage Length and Pretension on the Working Resistance of Rock Bolt Based on its Tensile Characteristics

“…Chang and others defined the surrounding rock stability index and then studied the stability of the surrounding rock with different anchorage lengths. They found that the full-length anchoring bolt support reduces the area of instability to a greater extent, compared to the end-anchoring bolt support [10]. Zou and Zhang studied the dynamic evolution characteristics of bond strength between bolt and rock mass under axial tensile load, and the mechanical behavior of fully grouted bolt considering the uneven surrounding rock stress around the bolt [11].…”