2017年02月06日

Hollow bar for concrete

With the increasing requirements of the railway tunnel safety, people are paying more and more attention to the higher geological anchoring technology. Traditional technology may have some shortcomings during the construction under broken rock, loose soil and conditions which are difficult to drill holes, such as fracture zones, decayed rock, gravel, sandy gravel, backfill ground. While self drilling anchor system consists of hollow anchor bar, coupler, nut, plate and sacrificial drill bit. Hollow anchor bar can be used as a drill rod, grouting pipe and source of anchoring force, which makes self drilling anchor system combine drilling, grouting and anchoring functions together.
Different type of drill bits can be used according to different geological conditions so as to achieve optimal result. The application of hollow anchor bar in the railway tunnels will largely save the construction cost and speed up the construction progress.
During construction process of mountain slope, rock face will be damaged after excavation or blast, it may have security problem of small block, so self drilling hollow anchor bar support is always be adopted.

1. When mountain slope fills soil and sweeps away loose rock, blast will be carried out if necessary.
At the same time, safety measures should be prepared well.

2. Positioning. Based on design scheme and geological condition of soil layer, theodolite, digital level and steel tap often are used to confirm self drilling hollow anchor bar’s elevation and separation distance. Then hole site will be determined and marks should be made. Allowable deviation between self drilling anchor’s holes should less than 15mm.

3. Drilling. Drilling machine should be used to form holes, which should be operated according to operating instruction. While drilling, installing anchor bolt to avoid collapse. Error of inclination and horizontal angles should be controlled in 1° and hole deviation rate should be less than 1/100.
During drilling, self drilling hollow anchor bar’s distortion and bend should be avoided.

4. Grouting. Proportion of water and cement paste should be debugged according to actual conditions.
Strength grade of cement should be not less than 30MP. Grouting technology quality requirements

should be confirmed according to trail of self drilling hollow anchor bar. Slurry returns from the bottom of hole until fresh slurry overflows orifice. Once cement face falls back, concrete supplement should be carried out twice in 30 minutes to ensure slurry is full.

5. Installing steel mesh and surface concrete construction.

6. Maintenance. After surface concrete construction, water injection should be done in time: 3 times in a day and no less than 3 days.

Except construction according to standard, quality inspection should be reflected in every link.


Posted by seo2@sinorockco.com at 18:16│Comments(0)TrackBack(0)

この記事へのトラックバックURL

http://hollowbaranchor.fukuokablog.jp/t11354
上の画像に書かれている文字を入力して下さい