盾构施工对桩基的影响及桩基近邻度划分

发布时间：2018-05-15 16:55

本文选题：盾构 + 正交试验　；参考：《岩土力学》2014年S2期

【摘要】：隧道盾构施工过程中因盾构对土体的扰动和盾构脱出而没有及时注浆或注浆量不够,通常会对隧道邻近的桩基造成影响,如桩基内力发生改变从而使桩基变形、移位等,影响了桩基的承载力和正常使用。正交试验是一种高效、快速的找出某种指标的主要和次要影响因素的方法。通过建立盾构施工过程中近邻桩基的弹塑性有限元模型,结合正交试验和方差分析,得到了盾构施工对近邻桩基的影响因素大小。结果表明,盾构隧道施工过程中对近邻桩基沉降影响大小的因素依次为:桩与隧道的距离、桩顶荷载、应力损失和土体物理力学性质;桩基在(2.5~3.0)D0(D0为隧道直径)以外,则桩基基本上不受盾构开挖的影响;桩顶沉降与桩顶原来的荷载相关性显著,桩顶荷载的大小反映了土体应力水平的高低。根据方差分析的显著性检验结果提出桩基近邻度的概念和计算公式,把盾构隧道周围的桩基分为非常近、近邻、远邻和非常远等4类桩,表明Ⅰ类桩和Ⅱ类桩受到盾构施工的影响较大,施工前应对桩基采取必要的保护和加固措施,Ⅲ类桩视情况进行处理,Ⅳ类桩一般不需要处理。
[Abstract]:In the course of tunnel shield construction, due to the disturbance of the shield to the soil and the shield out of the shield, there is no timely grouting or insufficient grouting, which usually affects the pile foundation adjacent to the tunnel, such as the change of the internal force of the pile foundation and the deformation and displacement of the pile foundation, which affects the bearing capacity and normal use of the pile foundation. By setting up the elastoplastic finite element model of the adjacent pile foundation in the shield construction, combining the orthogonal test and the analysis of variance, the influence factors of the shield construction on the adjacent pile foundation are obtained. The result shows that the influence of the shield tunneling on the settlement of the settlement of the adjacent pile foundation in the process of shield tunneling is the cause. The distance of the pile and the tunnel, the load of the pile top, the stress loss and the physical and mechanical properties of the soil; the pile foundation is basically not affected by the shield excavation in (2.5~3.0) D0 (D0 as the tunnel diameter); the pile top settlement is closely related to the original load of the pile top, and the size of the pile top load reflects the level of the soil stress level. The significance test results of the difference analysis put forward the concept and calculation formula of the near adjacent degree of the pile foundation, and divide the pile foundation around the shield tunnel into 4 kinds of piles which are very close, near, far neighbour and very far away. It shows that type I pile and class II pile are greatly influenced by the shield construction, and the necessary protection and reinforcement measures should be taken to the pile foundation before construction, and the situation of class III piles is considered. In general, type IV piles do not need to be treated.

【作者单位】：浙江科技学院建筑工程学院;
【分类号】：U455.43

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