临海深基坑钻孔咬合桩受力变形特性分析

Analysis of stress and deformation characteristics of drilling occlusive pile near sea deep foundation pit

以临海近圆形深基坑钻孔咬合桩支护结构为研究对象,通过对比BSC-3D软件模拟结果和现场变形受力监测数据,探究基坑在不同开挖深度工况下咬合桩深层水平位移及咬合桩环撑结构轴力的变化规律。结果表明:近圆形深基坑在外侧土压力作用下,产生“拱效应”,基坑在“凹”“凸”处受力变形复杂;开挖到基坑底时,“凹”处咬合桩深层水平位移最大为2.28mm;环撑结构受力分布基本均匀,在“凹”处轴力较小,“凹”“凸”连接处轴力较大;环撑冠梁、环撑腰梁对咬合桩支护结构内支撑起关键作用,当开挖到环撑腰梁位置时,环撑受力由冠梁环撑为主逐渐转变为环撑腰梁受力为主。在类似基坑工程施工过程中,应加强“凹”处水平位移监测,以及“凹”“凸”连接处轴力监测。

Taking the drilling occlusal pile supporting structure of sub-circular deep foundation pit near the sea as the research object,the deep horizontal displacement of occlusal pile and the axial force of occlusal pile ring support structure under different excavation depths were explored through BSC-3D software simulation and field deformation monitoring data.The results show that the sub-circular deep foundation pit produces"arch effect"under the action of external soil pressure,and the force deformation of the foundation pit in the"concave"and"convex"is complicated.When the excavation reaches the bottom of the foundation pit,the maximum deep horizontal displacement of the occluded pile at the"concave"is 2.28 mm.The force distribution of ring brace structure is basically uniform,and the axial force at the"concave"is small,while the axial force at the"concave"and"convex"joint is large.Ring-supported crown beam and ring-supported waist beam play a key role in the internal support of occlusive pile supporting structure.When the excavation reaches the position of ring support beam,the ring support force gradually changes from crown beam to ring support beam.In the construction process of similar foundation pit engineering,the horizontal displacement monitoring of"concave"and the axial force monitoring of"concave"and"convex"joint should be strengthened.