Strain of AM bottom-expanded piles in static loading tests

By introducing the full hydraulic construction, the technique of AM bottom-expanded piles is used for the bridge piles in Wuhan Tianxinzhou Yangtze River Bridge, which is applied for the first time in the railroad engineering in China. Based on the linear measuring principle, a high-precision sliding micrometer is applied to strain testing of AM piles under static loading condition. Because of its high measuring accuracy, the sliding micrometer has a great application value in tip resistance and side friction of pile tests. According to the strain results of three test piles, the tip resistance of AM piles begin to work since the 5th stage of loading applied, and the ratio of the tip resistance to the whole load is about 47.3 ％ . The AM piles belong to friction piles and they have obvious characteristics of end-bearing piles, and the AM piles have a huge potential tip resistance at later stage. The strain of AM pile tests provides a good reference for their design.