In the construction of slope protection, why must be self drilling hollow anchor bolt? There are some reasons in below:
1. Integration of drilling, grouting and anchoring as a whole. Self drilling hollow anchor bolt can ensure the anchoring effect in complex ground conditions. It has the features of safety, reliability and efficiency.
2. Rapidly initial support, control the deformation and ensure the stability of surrounding rock.
3. The hollow design makes the anchor bar achieve the function of a grouting pipe, thus avoiding the loss of mortar caused by the grouting pipe in the traditional construction process.
4. The grouting is full. The pressure grouting can be realized to improve the quality of the project.
5. Due to the role of the accessories, the hollow bar can be well placed in the middle. The mortar can cover the hollow bar in full length, avoid the risk of corrosion, and achieve the purpose of long-term support.
6. Easy installation. It’s easy to place the plate and nut without processing thread on site.
7. Combined with the matched grouting pump and grouting technology, at present, self drilling hollow anchor bolt is the only anchoring system to solve the problems of traditional anchoring support in China.
Water power resources in Brazil is rich, famous Amazon, Parana River and Sao Francisco River three river systems run through it. In Brazil, hydropower has occupied large composition in all electricity-generation system. With increase of economy every year, energy supply needs to be increased accordingly. So, there are plenty new hydropower engineering is to be constructed.
Santo Antonio Hydropower Station is the fourth largest hydropower station in Brazil, located on Madeira River in Rondonia, Brazil. Madeira River is the main tributary of Amazon River and its average flow is 18ooo m³/s with obvious seasonality.
This project includes 4 plants and 2 spillways. Main dam segment belongs to RCC dam and two ends belongs to earth-filled dam. 44 bulb tubular turbine generating sets will be installed, they are total 3568 MW and predicted to finish installation in November this year.
The bedrock of dam is rough, cracks and discontinuous surface rock mass can be seen everywhere, which has high risk of piping.
When constructing hydropower station, cost reduction and research of new technology will also be followed-up, which are believed having huge potential. Self drilling anchor can put drilling, grouting and anchoring at the same time, is the most convenient and stable supporting method. In the long-term, self drilling anchor has advantages of economy, endurance and security.
Friendship Tunnel is a cross-border tunnel connecting China and Laos, with a the total length of 9.68 km, 7.17 long in China and 2.51 km long Laos, planned to spend 56 months. The name of Friendship Tunnel means the deep friendship between the two countries. On June 22, 2016, Friendship Tunnel officially started construction, which marked that the midline of Trans-Asian Railway Network started to enter a substantive stage. The project leader of China Railway Erju Group (CREGC) said Friendship Tunnel has poor engineering geological conditions and high risk of construction because of siltstone interbedded with mudstone. To ensure the safety and efficiency of tunnel construction, CREGC is in strict accordance with the design parameters of support. Friendship Tunnel would greatly push forward the“One Belt And One Road”.
Tips: Metis® self drilling hollow anchor bolt can be used as stabilization of tunnel portals, fore-poling, face stabilization, spilling, root piling and radial systematic anchoring， which is the choice of most engineers for tunnel engineering construction.
Metis® self drilling anchor is a hollow anchor, having the new integrated functions of drilling, grouting, and anchoring. It has the extended feature because self drilling anchor bolt can be lengthened by using coupling. It can be applied in the basement, under the bridge, the river, and a narrow construction environment, and now widely used in tunnels, mining, slope and other projects. It is suitable for hole collapsed areas and disease treatment, such as, reinforcing existing structures, grouting and filling cracks, etc. There are two specific cases in this article about the applications of self drilling anchor to illustrate the reinforcement effect.
Case 1. Beijing-Qinhuangdao Expressway slope reinforced with self drilling anchors
The slope is very unstable because rock fractures with a layer of mud and expansile kaolin are easy to expand and spall by rain, which has poor resistance to weather. It has achieved good effect in three years after using the reinforcement method of a self drilling anchor and jet anchor net. Click here and learn more.
In water conservancy projects and various underground works，there are generally complicated geological conditions such as soft and weak surrounding rocks and fault fracture zones. Especially in case of serious hole collapse and need of extreme long rock bolts，the construction of ordinary mortar rock bolts is very difficult.
Based on the construction of slope excavation support of the diversion channel for Banduo hydropower project, self drilling hollow anchor bolt instead of ordinary mortar anchor bolts in case of broken rocks and clay rocks can overcome the problems such as slow construction progress, impossible insertion of bolts, hole collapse, and ensure the overall stability of surrounding rocks. Under the lithology, the geological conditions is mainly thin sand slate sandstone and the width of broken belt is general 5 ~ 20 cm. This project uses neat cement grout to grout, water-cement ratio of 0.45 /0.5: 1, and the pressure of injection pump infusion is less than 0.3 MPa.
Soil nailing wall supporting is a new type of retaining structure for the excavation and slope stability in recent years developed. The technology is from the 1970s, nearly 30 years’ history. The first application of soil nail wall supporting in the engineering was in France,1972. The first application in the USA was in 1974 and Germany in 1979 firstly built a permanent soil nailing works. The earliest application in China was probably in the slope stability engineering of Liuwan Mine, Shanxi province in 1980. Compared with foreign countries, China’s development in the soil nail wall supporting technology also has some unique achievement, mainly in the following aspects:
1.Soil nail wall combines with waterproof curtain, which emerges a kind of water-stopping soil nail wall.
2. It develops a type of soil nails into the grouting for the hole, difficult to hole in sand and soft soil layer.
3. It develops the technique of combining soil nail wall with prestressed anchor, namely self drilling anchor bolt.
4. Fore reinforcement is developed for the poor excavation of the soil and short self-stabilization.
5.It exploits the simple, economical construction method of Metis® self drilling anchor bolt.