Anchor bolt support can give full play to the stability of surrounding rocks, and it is widely used in the surrounding rock support of highway tunnels. Permanent support usually use the ordinary mortar anchor bolt, but the grouting isn’t full at times. Especially when the anchor bolt is inclined upward or the length is more than 3m, the grouting effect is hard to guarantee due to the overflowing mortar, leading to voids in the hole, which will often cause the actual effective area fails to meet the design requirement. In addition, it’s hard for the ordinary mortar anchor bolt to drill holes in the broken and loose surrounding rock, but easy to collapse and stick, and even hard to pull out the bolt, which will cause the anchor bolt support can’t be carried out.
SDA bolt combines drilling, grouting and anchoring functions together. It can ensure the construction efficient, safe, reliable and good anchoring effect under complex conditions, such as broken rock, loose soil and the conditions which are difficult to drill holes.
The geological structure of Luniao steep ridge tunnel was very complicated. Both the entrance and exit were at the mountains pass area. The stability of surrounding rocks was poor and the tunnel itself was mainly composed of limestone. This project adopted SDA bolt to reinforce the dangerous rocks, which ensured the smooth completion of this project. After the test, SDA bolt had the advantages of full mortar, caulking fully, construction safety and reliable anchoring. Since it was put into use, the effect was pretty good.