地铁吊脚桩深基坑围护结构及土体变形规律

The Deformation Law of Retaining Structure and Soil of Deep Foundation Pit by Suspending Pile in Metro

通过分析典型"土岩二元结构地层"深基坑的特点,选取青岛地铁李村站的吊脚桩深基坑作为研究对象,采用ABAQUS有限元仿真计算,并结合大量现场监测数据分析的方法,对吊脚桩深基坑围护结构及土体的变形规律展开了研究。研究结果表明:"土岩二元结构"地层深基坑具有和土质基坑或岩质基坑显著不同的特点;随着基坑开挖深度的增加,围护结构的侧移逐渐增大,最终的侧移形态为上部小、中下部大的"花瓶形";地表沉降随基坑开挖深度的增加而增加,在开挖深度小于2 m时,地表沉降表现为"三角形"模式;随着开挖深度增加至6 m,沉降模式由"三角形"转变为"凹槽型",此后沉降形态保持为"凹槽型"不变。基坑深层土体沉降曲线性状与地面沉降相似,但沉降的影响范围随着深度的增大有所减小,土岩界面以下地层受上覆土层开挖卸荷而产生的回弹影响非常小。

The characteristics of the deep foundation pit in soil rock dual structure strata firstly was analyzed. The deep foundation pit by suspending pile in Qingdao subway Lijiacun station is selected to as the research object. Using ABAQUS finite element simulation analysis method combined with a large number of field monitoring data, to study the deformation law of retaining structure and soil of deep foundation pit by suspending pile. The results prove that , the characteristics of the deep foundation pit in soil rock dual structure strata is significantly different from soil foundation pit or rock foundation pit. With the increase of excavation depth, palisade structure lateral increase gradually, finally forms of lateral upper for small, big part of the“vase”. Surface subsidence increases with the in-crease of excavation depth, when the excavation depth is less than 2 m, the surface subsidence is shown as“trian-gle” mode. With the increase of excavation depth to 6 m, settlement pattern by “triangle” into “groove” type, then settlement form for “groove”. Deep foundation pit soil settlement curve characters and ground subsidence are similar, but the influence of the subsidence range reduced with the increase of depth. The soil rock interface under formation by overlaying soil excavation unloading rebound effect is very small.