The Support Method in Mambilla Hydroelectric Station
December 3, China-Africa Cooperation Forum was held in Johannesburg, which aims to promote the development of electric power and infrastructure in Nigeria. Especially the coastal railway project linking Lagos with Carnot and Mambilla hydroelectric station, both sides had discussed and China will provide support.
Mambilla Hydroelectric Station is located on Donga River between Nigeria and Cameroon, which is a project for inter-basin water and electricity generation. This project used natural topographic drop of Mambilla Plateau (about 1000m) and got water from Donga River, then realized long-distance water diversion and electricity generation.
It will be the largest hydroelectric project in Nigeria. There are 12 machines and total capacity is 3050MW, whole investment is about 6.4 billion dollars. Mambilla Hydroelectric Station includes three dams, one weir, two tunnels for water delivery, underground powerhouse, one switch station and two tailrace tunnels, etc. So it also needs plenty materials and the support method is necessary.
Compared with common steel support, soil nailing is quite convenient and efficient. It combines drilling, grouting and anchoring together. Firstly, drill machine drills holes, then soil nail is being put into holes and finally, flurry is grouted to unite soil, steel and slurry.
Soil nailing is a slope supporting technology, taking soil nail as the main stress component. It consists of intensive soil nail groups and waterproofing system to enhance the supporting effect. Nowadays, it has been applied in different geological conditions to support projects.