预加轴力对基坑交叉工程稳定性影响

The study of additive supporting axial force of effect on the stability of foundation pit crossing engineering

针对长春卫星广场节点范围内快速路结构工程与既有车站主体结构交叉的问题,综合现场实测和无预加轴力不对称开挖的模拟分析,对原有的基坑开挖方案进行了模拟和优化。结果表明:当采用无预加轴力不对称开挖方案时,基坑桩体水平位移呈现出朝向基坑且上大下小的变形特征,其中由于土体开挖引起荷载变化造成的最大变形量占总变形量的75%以上;采用增加200kN预加轴力的优化方案后,基坑桩体水平位移呈中间大两端小的变形特征,桩体的最大水平位移减小了10.84mm,比原方案减小52.1%,与无预加轴力模拟的结果相比,西侧最大变形增大了0.31mm,东侧最大变形减小了0.82mm;方案优化后,两侧基坑变形趋于平衡并关于主体对称,减小了结构的剪力;桩体最大水平变形的位置下移至桩顶以下9m处,有效约束了桩体上部的变形。

This paper relies on the complex problem of the fast road construction projects cross with the main existing station structure within the scope of Satellite Plaza nodes to simulate and optimize the program in Changchun,which synthesizes field data and no pre-axial force asymmetry excavation simulation analysis.The results showed that in the asymmetric excavation simulation of no pre-axial force,the fast road pit pile showed variations of large deformation in upper part and small in lower toward pit,and the maximum deformation due to the digging and change of soil stress toke up more than 75% of the total deformation;after in-creasing pre-axis force 200 kN,the fast road pit pile showed variations of large deformation in the middle and small in both slides, the maximum horizontal displacement of fast road pile reduced 10.84 mm after optimization,and decreased by 52.1% than before;the maximum deformation of west increased 0.31 mm compared with no pre-axis force simulate results,while the maximum de-formation of east decreased 0.82 mm,both sides of the pit deformation tended to balance and symmetry with respect to the subject after optimization,which reduced the structure shear force.The maximum position of fast road pile deformation moved down to 9 m below the top of the pile,and effectively constrained the deformation of the upper part of the pile.