土岩复合地层深基坑开挖数值模拟及变形分析

Numerical simulation of excavation of deep foundation pit and analysis of internal force deformation of support system in Soil rock composite stratum

为研究土岩复合地层条件下深基坑开挖过程中支撑结构的变形机理,以内支撑为支护形式的某基坑工程为依托,建立该基坑的三维有限元模型,分析该基坑在开挖过程中各方面位移、内力的变化规律及规律形成原因,为类似基坑工程设计提供借鉴。结果表明:随着基坑开挖,围护结构水平位移呈现中间向坑内凹陷、两头小的形态,围护结构位移最大值在靠近约小于1/2基坑深度处;水平支撑主要因两侧围护桩变形而受压,为了限制支撑的位移,支撑之间的连梁多表现为受拉;立柱竖向位移是中间柱大,边柱小,有明显的空间效应。

In order to study the deformation mechanism of the support structure during the excavation of deep foundation pit under the condition of earth-rock composite stratigraphy,the three-dimensional finite element model of the foundation pit is established on the basis of a foundation pit project with the internal support as the supporting form,and the change law and law of the internal force in the excavation process of the foundation pit are analyzed,so as to provide reference for the engineering design of similar foundation pits.The results show that with the excavation of the foundation pit,the horizontal displacement of the enclosure structure shows the form of a depression in the middle to the pit and small at both ends,and the maximum displacement of the enclosure structure is close to about 1/2 of the depth of the foundation pit.The horizontal support is mainly compressive due to the deformation of the enclosure piles on both sides,and the main role of the connecting beam between each support is to limit the displacement between the supports to each other in order to behave as tension;the vertical displacement of the column is that the middle column is large and the side column is small,and there is obvious spatial effect.