临河深基坑中超长锁扣钢管桩围堰变形分布研究

Deformation Distribution Study on Super Long Locking Steel Pipe Pile Cofferdam in Riverside Deep Foundation Pit

锁扣钢管桩围堰由于自身整体刚度大、加工制作简便、回收利用率高等优点,近年来在城市轨道交通的桥梁基础工程施工中广泛应用。为了深入研究临河深基坑中超长锁扣钢管桩围堰的工作性能,以西安市地铁10号线泾河大桥为背景,通过对坑周地表竖向沉降及超长锁扣钢管桩深层水平变形进行监测,分析了临河富水砂卵石层深基坑开挖过程中坑周竖向沉降分布规律及钢管桩深层水平变形分布规律,并研究了临河距离对二者分布规律的影响。结果表明:随着基坑临河距离的增大,坑周竖向沉降分布规律发生改变;锁扣钢管桩均发生朝向深基坑方向的水平位移,曲线均呈“弓”形分布;封底混凝土浇筑后,锁扣钢管桩深层水平变形未发生明显变化,随着临河距离的减小,向河侧锁扣钢管桩水平位移由减幅逐渐变为增幅;不同临河距离的基坑,在开挖初期,锁扣钢管桩深层水平变形分布存在差异,随着开挖的进行,“弓”形趋势愈加明显。该结论可为类似工程提供参考。

Locking steel pipe pile cofferdam has been widely used in the construction of bridge foundation engineering of urban rail transit in recent years due to its advantages of large overall stiffness,simple processing and high recyclability.To study the working performance of super-long locking steel pipe pile cofferdam in riverside deep foundation pit,taking Jinghe Bridge of Xi’an Metro Line 10 as a case study,the vertical settlement around the pit and the deep horizontal deformation of super-long locking steel pipe pile are monitored.The distribution law of vertical settlement around the pit and the distribution law of deep horizontal deformation of steel pipe pile during the excavation of deep foundation pit in riverside water-rich sandy pebble layer are analyzed,and the influence of riverside distance on the distribution law of the two is studied.The results show that with the increase of the distance from the foundation pit to the river,the distribution law of vertical settlement around the foundation pit changes.The locking buckle steel pipe piles all have horizontal displacement in the direction of deep foundation pit,and the curves display a'bow'shape.After the bottom sealing concrete is poured,the deep horizontal deformation of the locking steel pipe pile does not change significantly.As the distance to the river decreases,the horizontal displacement of the locking steel pipe pile to the riverside gradually changes from decreasing to increasing.During the initial stages of excavation,there are differences in the distribution of deep horizontal deformation of locked steel pipe piles with different distances to the river.And as the excavation progresses,the trend of'bow'shape becomes more and more obvious.The conclusion can provide a reference for similar projects.