As a new construction technology, self drilling rock bolt has been widely applied in hydroelectric station and it has overcome several technical difficulties in loose rock conditions. In high slope supporting construction of hydroelectric station, self drilling rock bolt overcomes the difficulties of forming hole and hole collapse, etc. And it realizes the primary stabilization combining with jetting cement and drainage hole method, which accumulates experience for further application of self drilling rock bolt.
The features of self drilling rock bolt:
Self drilling rock bolt is hollow and has full thread on its surface. Coupling is adopted to lengthen it and one-off drill bit is installed on the front end.
Because of special structures, self drilling rock bolt has following advantages:
1. High efficiency: Self drilling rock bolt combines drilling, grouting and anchoring together, several processes can be done at the same time, which is time-saving and high-efficient.
2. Suitable for stratum which difficult to drill hole: When encountering loose and broken surrounding rocks, it is difficult to drill hole and easy to collapse; while self drilling rock bolt can overcome this situation. After drilling hole, anchor bar still stays in the hole, which ignores collapse, saves time and reduce construction difficulties.
3. High adaptability: There is whole thread on the surface of self drilling rock bolt, it can be cut at any position. So it is suitable for different construction conditions.
4. High anchoring force: The thread of self drilling rock bolt divides into R-thread and T-thread. They can both connect with coupling tightly and have good bonding effect with grouting slurry.
5. Good anchoring effect: When grouting, slurry is from the bottom to orifice, the effect is full and dense, grouting quality is good.
6. Simple to construct: Compared with common rock bolt, self drilling rock bolt has decreased the processes of pulling out of hole, installing anchor bar and inserting grouting pipes, which is quick and simple.
In a word, self drilling rock bolt has played a crucial role in high slope of hydroelectric station. It has obvious features, such as single rock bolt has big tensile pulling force, great depth and small project amount, it is suitable for different geological conditions. Adopting self drilling rock bolt to construct project can control or reduce the occurrence of rock burst, enhance ability of anti-seismic and control deformation effectively.