天津医院深基坑工程中地连墙与排桩的应用研究

发布时间：2018-06-25 05:17

本文选题：排桩 + 地下连续墙　；参考：《天津大学》2014年硕士论文

【摘要】：本文以天津医院改扩建一期工程为背景,基坑开挖深度14.30m。通过在实际工程中深基坑支护形式由地连墙转变为排桩结构形式,前后比较了两种支护形式的优缺点,并在地连墙、排桩支护结构形式中对稳定性、变形效果采用软件模拟方式进一步分析。主要做了以下几方面的工作:1、地连墙支护结构形式在工程中首先被采用,但在实际施工中出现了难以预料的不良施工效果,通过分析设计、施工、地质条件等因素,得出了地连墙支护结构在本工程中的不利原因。由此阐述了不宜在地质条件差,地下水位过高,地下20m左右还存在承压水易造成塌孔这样特定的地质条件下采用地连墙基坑支护形式。2、通过现场原因分析,专家论证,试验性施工等方法论证后转变基坑支护形式为排桩,从施工效果和软件模拟得到,排桩沿竖向的水平位移以及沿横向的水平位移的变形趋势都呈“弓形”,且位移值沿着基坑深度方向越来越大,但是位移最大值始终位于基坑开挖面以上附近。围护墙顶部的水平和竖向位移在开挖过程的变化趋势基本一致,且随着基坑开挖的进行,围护墙顶部的水平和竖向位移均呈现线性增加的趋势。3、基坑外侧的土体沉降值变化曲线均为“长凹槽形”,且沉降值不大,说明基坑在开挖的过程对基坑周边的地表的沉降影响基本一致。且随着基坑开挖的进行,基坑外侧土体的沉降值也跟着递增。基坑开挖对地表沉降的影响范围也随着基坑开挖的进行,而影响范围逐渐增加,一般在2.5~5.0倍的开挖深度。4、通过现场实测数据,基坑周边地下水位和周围建筑物均符合相关规范要求,所以采用排桩的深基坑支护结构对于基坑周边的地下水位和周围建筑物沉降的控制效果是良好的。研究表明,深基坑支护结构的选择,不但与工程所在地的地理环境和地质条件有关,它还与工程的其他施工工序有关。本工程施工工序的安排,对基坑支护工程的成败,有着深刻的影响,排桩较地下连续墙深基坑支护结构之所以获得成功,一个很重要的因素,就是合理调整了施工工序,将止水帷幕施工放在灌注桩施工之前,有效的阻断了地下承压水的侵扰,保证了灌注桩的顺利成孔。排桩的深基坑支护结构充分发挥了结构的优点,为今后的工程提供了具有一定参考价值的借鉴。
[Abstract]:In this paper, the excavation depth of the foundation pit is 14.30 m, based on the first stage reconstruction and extension project of Tianjin Hospital. Through the transformation of deep foundation pit support form from ground connecting wall to row pile structure in practical engineering, the advantages and disadvantages of two kinds of supporting forms are compared before and after, and the stability of these two kinds of supporting forms is compared in the form of ground connecting wall and row pile supporting structure. The deformation effect is further analyzed by software simulation. I mainly did the following work: 1, the ground connection wall support structure form was first adopted in the project, but in the actual construction there appeared unpredictable bad construction effect, through the analysis of design, construction, geological conditions and other factors, The unfavorable reasons of the ground-connected wall supporting structure in this project are obtained. In this paper, it is expounded that it is not suitable to adopt the retaining form of ground connected wall foundation pit under the special geological conditions, such as poor geological conditions, high groundwater level and 20 m underground pressure water, which can easily lead to collapse of holes. Through field cause analysis, experts prove that, After demonstration of experimental construction and other methods, the supporting form of foundation pit is changed to row pile. From the results of construction and software simulation, the deformation trend of horizontal displacement along vertical direction and horizontal displacement along lateral direction of row pile is shown as "bow". The displacement value is increasing along the depth of the foundation pit, but the maximum displacement is always near the excavation surface. The horizontal and vertical displacement at the top of the retaining wall is basically the same in the excavation process, and with the excavation of foundation pit, The horizontal and vertical displacements at the top of the retaining wall show a linear increasing trend. The settlement curves of soil outside the foundation pit are all "long grooves", and the settlement values are not large. It shows that the influence of excavation process on the surface settlement around the foundation pit is basically the same. With the excavation of foundation pit, the settlement of soil outside the foundation pit increases. The influence range of foundation pit excavation on surface settlement is also increasing with the excavation of foundation pit, and the influence range is generally at 2.5 ~ 5.0 times of excavation depth. The underground water level around the foundation pit and the surrounding buildings all meet the requirements of the relevant codes, so the control effect of the deep foundation pit supporting structure with row piles on the underground water level around the foundation pit and the settlement of the surrounding buildings is good. The study shows that the selection of deep foundation pit supporting structure is not only related to the geographical environment and geological conditions of the site of the project, but also related to other construction processes of the project. The arrangement of the construction procedure of this project has a profound influence on the success or failure of the foundation pit support project. One of the important factors for the success of the deep foundation pit support structure with the row piles compared with the underground continuous wall is the reasonable adjustment of the construction procedure. Before the construction of water-stop curtain is put into the construction of cast-in-place pile, the interference of underground confined water is effectively blocked, and the smooth formation of the bored pile is ensured. The supporting structure of deep foundation pit with row pile has brought the advantages of structure into full play and provided some reference for future engineering.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU753

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