北京地区群桩基础荷载传递特性的现场测试研究

首先对试验情况作了简要介绍,在此基础上对比分析了单桩和群桩、群桩中桩数(桩距)以及端承条件不同(纯摩擦与端承摩擦)等影响因素下,不同方案所得到的桩侧阻力、桩端阻力随荷载水平、位移变化的分布特点和发挥性状,讨论了北京地区群桩基础中桩土承台相互作用产生的各种“削弱”和“增强”作用性状和作用机理,并由此归纳总结了北京地区群桩基础侧阻力、端阻力的分布特点和模式。成果不仅对北京地区群桩基础应力分布计算所需的参数提供了实测数据,同时也对其它地区的桩基设计和研究起到参考和借鉴作用。

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.