In-situ tests on load transfer mechanism of group piled foundation in Beijing

A set of full scale in-situ tests are carried out on group pile foundation in the west part of Beijing Area. Six static load tests are done on instrumented cast-in-place single piles and group pile foundations with different number of piles and with different bearing conditions of the pile tips. A brief summary of the tests is provided, and the measured shaft and tip resistance in each test are presented, compared and discussed in detail with special focus on the procedure of the development and transfer mechanism of the resistance changing with the load and displacement. Based on these observations, the interaction mechanisms, presented as several ‘weaken’ and ‘strengthen’ phenomena in group pile foundation with regard to single pile are discussed, and the pattern and distribution characteristics of shaft and tip resistance are summarized. The magnitude of the load distribution ratio, used in the Geddes Solution for pile analysis is also suggested according to the results of these tests in Beijing Area.