Vertical bearing capacity characteristics of large-diameter DPC pipe piles based on field tests
Hu Hesong1 Tang Mengxiong2 Liu Chunlin1,3 Chen Hang1 Zhang Shuo1,3 Ling Zao2
1. Guangzhou Institute of Building Science Co., Ltd., Guangzhou 510440, China;
2. Guangzhou Construction Engineering Co., Ltd., Guangzhou 510030, China; 3. South China University of Technology, Guangzhou 510641, China
Abstract：The drilling with pre-stressed concrete (DPC) pipe pile is a large-diameter and non-soil-squeezing PHC pipe pile with pile shaft grouting, which is a new type of pile foundation developed in recent years. To study the vertical compressive bearing capacity of the new type of pipe, the static load and high-strain dynamic field tests on five DPC pipe piles with a diameter of 1m are carried out. The field test results show that the high-strain dynamic test can be used for detecting the bearing capacities of pile foundations, and its testing error is within 10%. The vertical ultimate bearing capacities of four DPC pipe piles embedded in rock strata with a depth of 0.5m may reach 20000kN, which shall be 13%～23% larger than those empirical values predicted from the slurry protected cast-in-place pile of the same diameter. The pile shaft grouting and rock-socketed/embedment depth of pile can effectively improve the shaft friction resistance of DPC pipe piles, and the measured value are more than 28% larger than the recommended value calculated from the Code of pile foundation for slurry protected cast-in-place piles. Although all the four piles are embedded into the moderately weathered rock about 0.5m, the tip resistance ratios are less than 30%, exhibiting the bearing behavior of friction-type piles. Based on the field test results, the vertical bearing mechanism of DPC pipe piles can be revealed, which shall be beneficial to the design and optimization of DPC pipe piles.
