Field tests of large-diameter rock-socketed bored piles based on the self-balanced method and their resulting load bearing characteristics

Abstract

Owing to the capacity limitations of reaction systems for field loading tests, it is very difficult to carry out ultimate load tests on large-diameter rock-socketed bored piles in mountainous areas. Therefore, the self-balanced loading test method was used in this study to determine the load capacity of large-diameter rock-socketed bored piles. Distributed optical fibre test technology was used to explore the mechanical behaviour of the piles, and steel strain gauges and sliding micrometres were used for comparison. The test results indicate that the self-balanced loading test method can effectively circumvent the limitations of reaction systems in traditional loading tests. The axial force distribution in the pile shaft along the length of the pile was found to exhibit a non-linear distribution with increasing depth that transmitted higher loads deeper and deeper along the piles as the applied loads were increased. Finally, pile shaft resistance was found to develop prior to pile tip resistance, with the shaft load share ratio decreasing as the tip load share increases with the increase in load. Furthermore, the reliability of distributed optical fibre technology for determining the load bearing characteristics of large-diameter rock-socketed bored piles in complex geological conditions is confirmed.

Keywords:

• Rock-socketed bored pile
• load capacity
• field test
• self-balanced method

Acknowledgements

The authors would like to acknowledge the National Natural Science Foundation of China and Guizhou Provincial Department of . The research was also substantially supported by Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education.