考虑盾构下穿施工影响的桩板结构参数优化研究

Research into the Optimization of the Parameters of Pile-Plank Structures with the Effect of Shield Tunneling Construction Considered

为研究盾构隧道施工扰动对上跨桩板结构的影响,以厦门地铁4号线浅埋盾构开挖段为背景,利用数值方法建立软土地层中盾构动态开挖模型,结合现场实测,总结了桩板结构各部件在盾构扰动作用下的变形响应,进一步分析了结构参数优化在抵抗扰动变形方面的效果。结果表明:桩身水平变形随盾构开挖逐渐增大,刀盘驶过目标桩1.0D时达到最大值,随后因地层损失出现变形回弹;在刀盘到达目标断面前后,盖板竖向变形表现为先隆起后沉降,并在开挖空间上方出现沉降槽,刀盘驶过断面2.0D时,结构变形保持稳定;桩长不变,适量增加桩径、缩小桩间距,可减小桩身变形量,增加桩长将有效降低桩端变形,从而使整体变形得到控制;盖板厚度增大时,可起到降低其竖向变形的作用。

In order to study the effect of the construction disturbance of the shield tunneling construction on the pile-plank structure overspanning the tunnel to be built in soft soil, a dynamic shield tunnel excavation model is established by means of the numerical method in the present paper, with Line 4 of Xiamen Metro as the technical background. In combination with field tests, the deformation of the components of the pile-plank structure caused by the shield disturbance is summarized, upon the basis of which the effect of the optimization of the structural parameters on resisting the disturbance-caused deformation is further analyzed. The results show that the horizontal deformation of the pile gradually increases with the excavation of the shield, and reaches the maximum when the cutter head passes the target pile 1.0D,then the pile deformation rebounds due to the formation loss.During the forward movement of the cutter head, the vertical deformation of the plate tends to be first uplifting and then settling, and a settlement groove appears above the excavation space. When the cutter head drives over the target cross section 2.0D, the structural deformation remains stable. If the pile length is kept constant, increasing the pile diameter and narrowing the pile spacing can appropriately reduce the pile deformation. Increasing the pile length can effectively reduce the deformation of the pile tip, so the overall deformation is controlled. Increasing the thickness of the plate can reduce its vertical deformation.