根键位置对根式桩水平承载特性的影响研究

Effect of the position of root on the horizontal bearing capacity of root pile

通过4组室内模型试验,将根式桩与等截面桩的水平承载特性进行了对比研究,测得各级荷载下的桩身变形、桩身弯矩、水平极限承载力以及桩侧土压力的变化规律。设置了3组不同的单层根键位置分布的根式桩,初步探讨根键分布位置对水平承载力的影响并且通过数值模拟验证试验的可靠性。在本文试验条件下,底层根键、中层根键、顶层根键布置的根式桩较等截面桩的水平承载力分别提升了60%、120%、150%。根键作为"支点",向上层布置能够提供更强的抵抗作用,桩土协同作用深度范围增加,同时能够减小桩身的最大弯矩。顶层根键布置的根式桩不能完全发挥上层土体强度,向上布置的根键对水平承载特性的提升效果有限。

Based on model test method,4 groups of comparative model tests on the horizontal bearing capacities of single-layer root pile and equal diameter pile were carried out.The distribution of the deformation of piles,the bending moment of piles,the ultimate bearing capacity,and lateral soil pressure were measured under different levels of horizontal load.The ultimate bearing capacity of 3 different root piles with different arrangement of root was analyzed.The reliability of the test is verified by numerical simulation.The results show that the ultimate horizontal bearing capacity of root piles embedded in sand increased by 60%,120%and 250%respectively compared with equal diameter pile.The root,as fulcrum,which it is in upper part of pile,can provide greater resistance,the range of soil-pile interaction increases and at the same time,the existence of root can reduce the maximum bending moment of the pile.The root pile of which the root arranged in the top layer can not interact with soil completely and the effect of horizontal bearing capacities is limited.