摘要
既有建筑物地下空间增层过程中,既有支护桩和基桩不足以抵抗二次开挖所引起的侧向土压力,需要增加新的支护桩以保证原有建筑物的稳定。形成的新体系中,各桩的受力特性有很大的不同。因此,采用室内模型试验方法,研究双排支护桩和基桩的桩顶水平位移及桩身受力随开挖深度的变化规律。结果表明:既有、新增支护桩的桩顶水平位移随二次开挖深度的增加而不断增大,但新增支护桩的桩顶位移增长速度比既有支护桩的缓慢,基桩的桩顶水平位移随开挖深度的增加基本保持不变。另外,在既有基坑二次开挖条件下,支护桩桩身的弯矩分布呈中间大、两边小的趋势,基桩桩身弯矩呈“S”型分布,基坑中部的新增支护桩弯矩大于既有支护桩弯矩,中心位置处的新增支护桩分担土压力的作用更强。在空间效应影响下,从中心桩到边角桩,支护体系的桩顶水平位移逐渐减小,随着开挖深度的增大,中心桩的桩顶位移和桩身弯矩增长速度均最快。
During the downward expansion of the basement of an existing building,the existing support piles and foundation piles are unable to withstand the lateral earth pressure caused by the additional excavation.Supplementary support piles need to be added to ensure the stability of the building.The force characteristics of each pile in the newly-formed system are different.Therefore,indoor model test was adopted to study the variation of the top horizontal displacement and the body stress of the double-row support piles and foundation piles with the excavation depth.The results show that the horizontal displacement of the existing-supplementary row piles increases with the depth of the second excavation.However,the displacement of the supplementary support piles grows more slowly than that of the existing support piles.The horizontal displacement of the foundation piles remains basically constant with the increase of the excavation depth.In addition,during the second excavation of the original foundation pit,the bending moment distribution of the double-row support piles is large in the middle and small on both sides while the bending moment of the foundation piles is“S-shaped”.In the middle of the foundation pit,the bending moment of the supplementary support piles is greater than that of the existing support piles.The supplementary support piles located at the center have a stronger role in sharing the earth pressure.Under the influence of spatial effects,the horizontal displacement of the support system decreases gradually from the center piles to the edge piles.As the excavation depth increases,the growth rate of displacement and bending moment of center piles is the fastest.
作者
孔德森
吴绍娟
马顺顺
王凯
KONG Desen;WU Shaojuan;MA Shunshun;WANG Kai(College of Civil Engineering and Architecture,Shandong University of Science and Technology,Qingdao 266590,China;Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China)
出处
《山东科技大学学报（自然科学版）》
CAS
北大核心
2023年第6期49-56,共8页
Journal of Shandong University of Science and Technology(Natural Science)
基金
山东省自然科学基金项目(ZR2019MEE027)。
关键词
基坑
增层开挖
支护桩
桩基础
模型试验
foundation pit
additional excavation
support piles
pile foundation
model test
