Abstract：Based on the cumulative evidence of O-cell load test for rock-socket bored piles with large diameter and extra
length for a bridge project，this paper introduces the theory of O-cell load test and the method of confirming the load. The po原
sitioning of loading equipment and the technology of boring and casting of long length rock-socket bored pile are also dis原
cussed and some views of the author are proposed to provide reference for similar projects.