Abstract: The application of current high-strain dynamic testing method to determine the bearing capacity of single piles depends on the experiences of the testing personnel, and the solution is not unique. To overcome these shortcomings, a new direct high-strain testing method is introduced in this paper. A finite element model is developed for a cast-in-place pile to analyze the effectiveness of the direct high-strain method for the bearing capacity of single piles. It is shown that the finite element model can accurately simulate the results in the published literature. By carrying out finite element dynamic analysis, the stress field, displacement field, velocity field and acceleration field of the pile for a hammer blow are obtained. According to the finite element calculation results, the bearing capacity is determined using the direct high-strain method. The bearing capacity determined by the direct high-strain method is consistent with that from static pile load test. The direct high-strain method eliminates the problem of multiple solutions in the existing high-strain method. Therefore, a unique bearing capacity of single piles can be obtained using the new direct high-strain testing method.

Key words: pile foundation, high-strain method, ultimate bearing capacity, finite element simulation