Abstract
The left-hand rolling-thread steel bolt has been proposed as a new bolt for controlling roadway surrounding rock. To explore the mechanism of a left-hand rolling-thread steel bolt in roadway surrounding rock control, its pretightening forces, tensile strengths, anchoring forces, and maximum working resistances were compared to normal right-hand full-thread steel bolts in the engineering context of the 1301 haulage roadway in the Daxing Coal Mine. Then, the left-hand threaded steel bolt was applied to the 1301 haulage roadway that the right-hand threaded steel bolt failed to control. The results indicated that due to the different effective tensile section area, the yield strength and tensile strength of the left-hand threaded steel bolt with the same material and diameter were more than 10% larger than those of the right-hand threaded steel bolt. Due to the different thread directions, the anchoring forces of the Φ18 and Φ20 left-hand threaded steel bolts were 46.2% and 33.3% greater than those of the right-hand threaded steel bolts, respectively. In the 1301 haulage roadway, the maximum pull-out force of the left-hand rolling-thread steel bolt with the same diameter was obviously greater than that of the right-hand full thread steel bolt. The displacements of the 1301 haulage roadway supported by the left-hand threaded steel bolt were not great. So, the left-hand threaded steel bolt can effectively control the surrounding rock in the 1301 haulage roadway.
Highlights
The purpose of controlling the surrounding rock in mine roadway is to ensure that excavations remain safe and open for their intended life span
The deformation of the rock surrounding the 1301 haulage roadway was large. This showed that the normal right-hand full-thread steel bolt cannot effectively control the stability of the surrounding rock in the 1301 haulage roadway
To find an effective support structure for the 1301 haulage roadway, this paper systematically investigated the mechanism of the normal right-hand full-thread steel bolts and left-hand rolling-thread bolts in roadway surrounding rock control
Summary
The purpose of controlling the surrounding rock in mine roadway is to ensure that excavations remain safe and open for their intended life span. The research and application of the left-hand rolling-thread steel bolts in mine roadway surrounding rock control are still in the initial stage. The deformation of the rock surrounding the 1301 haulage roadway was large This showed that the normal right-hand full-thread steel bolt cannot effectively control the stability of the surrounding rock in the 1301 haulage roadway. To find an effective support structure for the 1301 haulage roadway, this paper systematically investigated the mechanism of the normal right-hand full-thread steel bolts and left-hand rolling-thread bolts in roadway surrounding rock control. The superiority of the left-hand rolling-thread steel bolts in comparison with the normal right-hand full-thread steel bolts in the roadway surrounding rock control was verified through engineering application. The left-hand threaded steel bolts can effectively control the stability of the surrounding rock in the 1301 haulage roadway
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