Question:
The construction works in the city have the common feature is the area of narrow construction, high requirements in the treatment of noise, vibration, construction waste. In order to meet the above requirements, the technology of steel pipe screw was born. The technology of steel pipe screw has been used in Japan since 1999 on many construction projects such as bridges, bridge foundation, overhead rail, housing, schools, hospitals, factories.
Define:
Steel Pipe Screws are steel pipe piles with steel pile layered and lowered by rotating method. Steel pile head with two types of closed wings and open wings.
Characteristics:
+ Small construction space, low impact on existing traffic.
+ The steel wing at the pile feet acts as a pile base is expanded. The land is occupied by the pile body is pushed to the side to increase the strength of the ground around the pile. With these two characteristics, the bearing capacity of steel pipe screws is about 80% higher than that of bored piles of the same diameter and length.
+ When construction does not create excess sludge should not be treated waste.
+ Low noise and vibration so no impact on the foundation of the surrounding.
+ Not influenced by groundwater.
+ The construction time is short due to not using concrete should be able to bypass concrete time to reach the intensity.
+ Easy to install oblique pile.
+ Quality of piles is controlled by the production in the factory.
Construction method: The technology of steel pipe screw installation is very simple, compact device, does not occupy much area.
+ With a small diameter pile (closed wing), a pile driver with a pile head attachment is used. The construction sequence is as follows:
+ Large diameter piles (openings), constructed by pile turn device. The construction sequence is as follows:
Construction time:
For piles with a length of 48m, the pile speed is nearly 0.5 days / pile compared to the pile speed of 1.5 days / pile.
Economic - technical:
Analysis of economic / technical performance of a specific case shows that with the same strength: Steel screw screws need less number of piles but the cost of materials is higher than the bored piles. However, the cost for the pile and lower pile construction, and no cost for the treatment and transportation of waste. Therefore, the overall cost of the two bored pile measures and steel pipe screws is equivalent.
With the advantages of high loading capacity, simple fabrication and construction technology, saving time, reducing noise and waste land, suitable in conditions of limited construction site, the technology of screw pipe Japan's steel has shown certain advantages, when applied in the appropriate application areas.
Evaluate:
To be widely applied in Vietnam, it is necessary to improve the design and construction standards of this technology. In addition, it is necessary to analyze and compare the economic and technical efficiency of steel pipe screw technology compared to other technologies such as piles, bored piles. From there, the scope of application for technology, creating the highest efficiency.