Pile foundation project of Guoneng Zhejiang Zhoushan Power Plant Phase III 2×660MW Expansion Project is located in Zhoushan City, Zhejiang Province, invested by Guoneng Zhejiang Zhoushan Power Generation Co., Ltd. 83 grouted piles with pile diameter of 0.8m and 615 PHC piles were completed in the project.
Due to the complex geological conditions within the construction site, the upper backfill layer is about 3-8m thick, mainly composed of block stone and gravel, with a large block stone grain size of up to 1.5m, which makes it difficult to set up the grouting pile casing and settle the first section of PHC grouting piles, and is very likely to cause mud leakage and risk of dropping of the casing. Beneath the backfill layer is a thick flow-plasticized silt layer, which is very likely to cause the hole collapsing or shrinking. The bearing layer of the end of the piles is moderate weathered tuff with high rock strength, which is difficult to drill into. In view of the difficulties encountered in the construction process, the project department controlled the quality and efficiency of grouting piles by adopting methods such as reasonable deployment of mud performance, setting up 6-meter-long protection casing, and timely and reasonable adjustment of drilling technology and drilling tools according to different strata. Adopting methods such as reverse circulation secondary cleaning, reasonable organization of construction to ensure timely pouring of concrete after cleaning, etc., the project department effectively controlled the thickness of slag at the bottom of the hole to meet the design and specification requirements and ensured the quality of pile end formation of rock-entry piles. Before the construction of PHC piles, excavators were organized to explore the upper backfill layer, which effectively controlled the pile offset and pile body tilt when the first section of pipe piles was put into the ground, and ensured the quality of the piles.
This piling project started on September 22, 2022 and was completed on November 18, 2022, which lasted 58 days and the construction progress met the overall schedule requirements of the owner. The results of third party testing are all qualified.
