Field experimental study on prestressed concrete tube-pile bearing stratum softening in strong weathered rock formation of Shunde area

Abstract

In the Foshan Shunde District, for the bearing stratum of the prestressed concrete tube-pile in strong weathering granite gneiss and strong weathering silty mudstone, it is common for abnormal setting of static load test and ultra pile driving in re-pressed process. There is no unified explanation and exact conclusion on whether this problem is caused by softening of pile-end soils. In order to solve this problem, experiments for piles with different pile tip were conducted for evaluate the changing of strength, horizontal stress and bearing capacity of pile-end soils, using various situ techniques such as static cone penetration test, pressure meter test, high strain testing and static load test combined with laboratory test results. It implies that strong weathering granite gneiss and silty mudstone in Shunde area has softening potential, however, the softening of pile-end soils may not occur immediately after piling. In addition, the effect of type of pile tip on the bearing capacity of the bearing stratum was not obvious. According to this study, it was suggested that engineering investigation should be given attention to. This study will have important implications for determining the bearing capacity of pile and guaranteeing the project quality.