顶部带撑条形基坑排桩围护结构变形

Spatial Deformation of Long Strip Foundation Pit with Top Braced Pile Retaining System Considering the Effects of Construction Process

目的推导顶部带撑条形基坑排桩围护体系的桩顶位移表达式.方法以条形基坑常用的带顶部支撑排桩支护体系为研究对象,考虑实际施工过程以及冠梁的影响,基于最小势能原理推导了支护桩变形的简化公式,并对影响变形的支护参数进行分析.结果桩顶最大位移δmax随着悬臂开挖深度增加线性增加,且在相同开挖深度下,悬臂开挖深度所引起的桩顶位移要明显大于撑后开挖深度所引起的桩顶位移;桩顶位移随地基土水平抗力系数m值增大而迅速减小;桩顶位移随地面荷载q线性增长,但增速缓慢.结论悬臂开挖对桩顶位移影响较大,尽快加撑有利于控制基坑变形;地基土水平抗力系数m对桩顶位移影响较大;桩顶位移随地面荷载q增长而线性缓慢增大.

In this paper, spatial deformation of long strip foundation pit with top braced pile retaining system considering the effects of construction process is studied. Take long strip foundation pit with top braced pile retaining system as the research object, the deformation expression of the retaining pile is established here based on the principle of the minimum potential energy and at the same time considering the influence of the top beam in practical construction process. Then the parameters affected the deformation are discussed. The results show that the maximum displacement of pile head increases linearly with the cantilever excavation depth increasing, and the maximum cantilever excavation-induced displacement is greater than the braced ex- cavation-induced displacement in the same condition. The maximum displacement of pile head decreases rapidly with the ＂m＂ value increasing. The maximum displacement of pile head increases linearly with surcharge q increasing, but the growth rate is small. The conclusion is that there＇s a greater influence of the can- tilever excavation depth on the maximum displacement of pile head, so installing support as soon as possible is beneficial to the limitation of the displacement. ＂m＂ is important to the control of the maximum displacement of pile head. The maximum displacement of pile head increases slowly with surcharge q increasing. Finally, compared the calculated result with the measured result, the method is proved to be feasible.