STATIC LOADING TEST OF A SELF-BALANCED APPROACH TO A PILE IN THE YANGTZE RIVER

摘要

Pile foundations are increasingly applied to the rapid development of long-span bridges in our country. In any kind of pile foundation a static loading test must be undertaken to determine the ultimate compressive bearing capacity of a single pile under criterion GBJ7-89. The Beicha bridge test pile of the Runyang Highway Yangtze River Bridge located in the Yangtze River between Zhenjiang and Yangzhou, whose ultimate bearing capacity is up to 40,000 kN, is hardly possible to test in conventional methods. The self-balanced method (Osterberg, Load-cell) is a new static load test method, almost not limited by testing sites and ultimate bearing capacity, which can directly determine the ultimate side resistance and tip resistance. This paper discusses the method successfully applied to the test pile, instrumented with strain gauges and the method for converting the results of the self-balanced test to the conventional loading test results is put forward, which suits the design method. The results also indicate the method will have expanding prospects for testing bridge piles under conditions of high bearing capacity and for special testing sites.