Abstract
One of the important factors affecting the anchoring force of the end encapsulated bolt is the mechanical properties of the rock formation at the anchoring end. For the fully encapsulated bolt, its bearing performance is closely related to the mechanical properties of the bolt passing through the rock stratum and its permutation mode. In this study, a series of laboratory pull-out tests of multi-strata anchorage systems was carried out based on an actual engineering background. The bearing performances and failure mechanisms of the multi-strata anchorage system under different anchoring methods and combinations of rock stratum were studied. The evolution law of the axial force and shear stress of the Agent-Rock interface was also analyzed. The test results showed that, for end encapsulation, changes in the mechanical properties of the rock strata at the anchoring end caused differences in bearing capacity, while full-length encapsulation markedly reduced the disparities. The position of the stratum with the highest general interface shear strength affected the mechanical response of the anchoring interface. The progressive failure process of multi-strata anchorage systems was discussed, and suggestions for rock bolt support in coal mine roadways were also proposed.
Highlights
Academic Editor: ManojBolt support is the preferred support method for coal mine roadways and an important supporting technology for safe and efficient mining
There is a common cognition among management of Chinese coal mines that the hard rock layer on the roof should be chosen as the anchoring point
When the anchoring end of the bolt was located in hard rock, the loaddisplacement curves of fully encapsulation systems and end encapsulation systems were similar
Summary
Academic Editor: ManojBolt support is the preferred support method for coal mine roadways and an important supporting technology for safe and efficient mining. Due to gradual deterioration of engineering conditions, more coal mines have experienced a multitude of problems to support roadways facing difficult conditions, such as large deformation of soft rock roadway, and fatigue failure of surrounding rock [9] under high ground stress from a strong mining roadway. These complex and difficult roadways create higher demands for the anchoring strength of the bolting system, given the sensitivity of surrounding rock deformation, and for the durability of support. Excessive pursuit of this practice will result in unreasonable lengths of supporting components, leading to a weakened active support of the bolts and cables and a poor control of the support system
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