FRP has been widely used in urban water supply and drainage projects due to its advantages of light weight, high rigidity, smooth inner wall, low frictional resistance to water flow, good corrosion resistance, convenient construction and installation, and long service life.
Geological conditions: the surface layer is 4112~5166m filled with soil, and the siltous soil below 016~716m below the fill layer, the water content is 59%~64%, the plasticity index is 25~26, and the bearing capacity is low. After comparison, in order to save engineering investment, the design uses prestressed reinforced concrete pipe and glass fiber reinforced plastic sand pipe, and partially uses a combination of steel pipes in the river channel. The project was completed and put into use in October 1999 and has been in good operation so far.
Glass fiber reinforced thermosetting resin sand pipe (referred to as FRP sand pipe) is a new type of pipe that appeared in the 1970s. At present, there are two kinds of processes for producing FRP sand pipes in China: one is glass fiber winding forming (called fiber winding sand pipe); the other is glass fiber centrifugal casting (called HOBAS pipe).
For the selection of FRP pipes: in the feasibility study design of the Zhanggan Reservoir's two dry water lines to the Gaoping City in the second dry water line of Zhangfeng Reservoir, the characteristics of pressurized gravity flow water are adopted for the project. The technical and economic comprehensive comparison of the glass steel pipe and the reinforced concrete pipe was carried out in terms of material properties, hydraulic properties, safety and applicability.
To this end, the head loss of different pipes at different pipe diameters should be calculated first. Due to the long water supply line, the main head loss is the loss along the path. In the feasibility study design stage, the local head loss can be roughly taken as 5% of the loss along the path.
In the water transportation project, the selection of pipe and pipe diameter should be based on the specific and actual conditions of the project, and the analysis and comparison of technology, economy, safety and construction period should be done. China's vast territory, the geology, topography, natural conditions, economic situation and the habits of applying pipes are different in each region, which has formed the diversity of the application of water pipelines.
Of course, with the continuous advancement of science and technology, the design and manufacturing technology of glass steel pipes is constantly developing and improving. The applicable construction and installation conditions and scope are gradually expanding, and with the industry standards and acceptance standards of pipes. As well as the continuous revision and addition of design and installation specifications, engineering designers will have more and better choices in the future selection of water supply engineering pipes, which can reduce costs and increase water delivery rate.