邻近建筑物基坑开挖的变形影响分析

发布时间：2018-06-12 20:13

本文选题：基坑 + 建筑物　；参考：《北京交通大学》2014年硕士论文

【摘要】：深基坑的开挖通常位于城市中心,基坑工程的周边环境十分复杂,通常存在各种建(构)筑物。这就要求基坑支护除满足强度要求外,还需满足变形要求。基坑的设计理念也由强度控制变为变形控制。而邻近建筑物的存在会使基坑开挖的变形与无建筑时有所不同。因此本文分别研究了无建筑、超载以及存在建筑物时基坑的变形规律,主要研究内容如下： 1、总结了基坑变形和建筑物变形的国内外现状,简要概述了基坑的变形机理和变形预测方法以及建筑物变形的预测方法。 2、本文建立FLAC3D三维模型,分析了基坑开挖的墙后地表沉降规律以及围护桩的水平变形规律。墙后地表沉降的变形模式均为凹槽型,围护桩的水平变形模式均表现为“中间大,两端小”的形状。并且分析了基坑的空间效应,基坑的墙后地表沉降以及围护桩的水平变形都有很明显的角隅效应,越是靠近基坑的角部,其变形值都在逐步减小。 3、研究了桩直径、桩间距、锚索水平间距对基坑变形的影响。随着桩直径的增大,基坑长短边的墙后土体地表沉降和围护桩的水平变形都逐渐减小；随着桩间距或锚索水平间距的增大,基坑长短边的墙后土体地表沉降和围护桩的水平变形都逐渐增大。 4、研究了邻近建筑物时基坑开挖的三维变形规律。分析了建筑物的存在对墙后地表沉降规律和围护桩水平变形规律的影响。发现存在建筑物时,基坑墙后的地表沉降仍为凹槽型,但在建筑物的边界处,沉降曲线的斜率发生突变,而且建筑物的最大沉降并不发生在建筑物下方土体处。并与超载作用下的基坑变形规律进行对比,发现建筑物作用下的墙后地表沉降要小于超载作用下的基坑变形,但围护桩的水平变形相差较小。 5、分析了建筑物的距离、荷载、刚度对基坑变形的影响。发现随着建筑物距离基坑边的增大,墙后的地表沉降和围护桩的水平变形逐渐减小；随着建筑物荷载的变大,墙后地表沉降和围护桩的水平变形增加。随着刚度的增大,建筑物下基坑的地表沉降逐渐减小,而围护桩的水平变形随着建筑物刚度的增大而增大。
[Abstract]:The excavation of deep foundation pit is usually located in the center of the city. This requires foundation pit support not only to meet the strength requirements, but also to meet the deformation requirements. The design concept of foundation pit is changed from strength control to deformation control. The deformation of foundation pit excavation will be different from that without building because of the existence of adjacent buildings. The main contents of this paper are as follows: 1. The present situation of foundation pit deformation and building deformation at home and abroad is summarized. The deformation mechanism and prediction method of foundation pit and the prediction method of building deformation are briefly summarized. 2. The FLAC3D 3D model is established, and the law of ground subsidence behind the wall of foundation pit excavation and the horizontal deformation law of retaining pile are analyzed. The deformation modes of the surface settlement behind the wall are all grooves, and the horizontal deformation modes of the retaining piles are "large in the middle and small in the ends". And the spatial effect of foundation pit is analyzed. The surface settlement behind the wall of foundation pit and the horizontal deformation of retaining pile have obvious corner effect. The closer the foundation pit is to the corner, the smaller the deformation value is. 3. The diameter of pile is studied. The influence of pile spacing and horizontal spacing of anchor cables on foundation pit deformation. With the increase of pile diameter, the soil surface settlement and the horizontal deformation of retaining pile decrease gradually, and with the increase of pile spacing or anchor cable horizontal spacing, The soil surface settlement and the horizontal deformation of the retaining pile increase gradually behind the wall of the short and short sides of the foundation pit. 4. The three-dimensional deformation law of the excavation of the foundation pit near the building is studied. The influence of the existence of the building on the surface settlement behind the wall and the horizontal deformation of the retaining pile is analyzed. It is found that when there is a building, the surface settlement behind the foundation pit wall is still grooved, but at the boundary of the building, the slope of the settlement curve is abrupt, and the maximum settlement of the building does not occur in the soil under the building. Compared with the deformation law of foundation pit under overload, it is found that the surface settlement behind the wall under the action of building is smaller than that of foundation pit under overload, but the horizontal deformation of retaining pile is smaller than that of foundation pit under overload. 5. The distance of building is analyzed. The influence of load and stiffness on foundation pit deformation. It is found that the surface settlement behind the wall and the horizontal deformation of the retaining pile gradually decrease with the increase of the building distance from the side of the foundation pit, and the surface settlement and the horizontal deformation of the retaining pile increase with the increase of the building load. With the increase of stiffness, the ground settlement of foundation pit decreases gradually, while the horizontal deformation of retaining pile increases with the increase of building stiffness.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU753

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