During tunnel construction, hollow and loose massive accumulation body often appears at portal section. The stability of rock is poor and local region is easy to happen collapse, so pipe shed is adopted to support in advance.
Because of poor rock stability, it’s difficult for drilling machine to form hole. While regular pipe shed is often steel tube with eyelet on its surface, jacking and grouting methods are needed when construction, so it’s difficult to install. Self drilling hollow anchor can solve this problem effectively.
Self drilling hollow anchor with drill bit can drill hole with common drilling machine. When reaching to designed location, self drilling anchor and drill bit are left in rock body, grouting can be proceeded directly. Unlike pipe shed, self drilling hollow anchor has injected holes on the top of drill bit, slurry is from bottom to eyelet, then diffuses all around to reinforce surrounding rock. Without pulling out hollow anchor bar and drill bit, it has strong adaptation on surrounding rock, even drilling and grouting at loose and broken surrounding rock.
Self drilling hollow anchor in loose surrounding rock tunnel can be used as pipe shed to support in advance, which can solve construction problems of hole-forming and installation.