黄土深基坑失稳机理与支护方案的优化设计

发布时间：2019-04-10 19:07

【摘要】：本文主要是针对不同地质条件下的黄土深基坑,研究黄土深基坑的失稳机理及相应的破坏模式;依据其破坏模式,给出两个及两个以上的初步设计方案,然后选出一种既经济,又能满足安全要求的方案。我国对深基坑的研究还很欠缺,对黄土深基坑的研究相对更少,文章对黄土深基坑的研究还是很有意义的。通过对西安黄土的研究,选取单层和多层地层组合结构的基坑。通过运用有限元软件研究其破坏模式,分析黄土基坑边坡的失稳机理,用以指导黄土深基坑支护方案的选型。引用西安市某个实际工程,分析地层为填土和黄土组合结构的基坑,针对该黄土深基坑初步设计了三种支护结构。通过有限元分析了三种支护方案,考虑多方因素,最后选定复合土钉墙是最优方案。选定最优的支护方案后,再通过对其进一步的优化,力争在安全的前提条件下,降低工程造价,节约资源。最后,利用现场的监测数据与有限元模拟的结果进行对比分析,验证了优化方案的可行性。得出主要结论如下:1)对西安市分布较广不同黄土组合地层结构的基坑,结合部分实际工程,选取合理的参数:通过有限元三维模拟,得出黄土组合地质的破坏模式主要分为片帮、滑移式、坐落式和局部崩塌式。2)选取西安市某个地层为填土和黄土组合结构的基坑,初步设计了锚拉单排桩、锚拉双排桩和复合土钉墙三种支护结构;采取有限元分析,综合考虑三种支护方案在位移大小、安全系数、工程造价、施工的难易程度及对周边环境的影响,判定复合土钉墙支护结构为优选方案。3)针对复合土钉墙支护结构进行了进一步的优化,主要是减小坡比、增大复合土钉的横竖间距、减小钢筋直径、减小土钉和锚杆的长度,最终在原来的基础上节约了 61.56万元左右;与现场的监测数据比较,也验证优化方案的可行性。
[Abstract]:In this paper, aiming at the loess deep foundation pit under different geological conditions, the instability mechanism and the corresponding failure mode of the loess deep foundation pit are studied. According to its failure mode, two or more preliminary design schemes are given, and then a scheme which is economical and can meet the requirements of safety is selected. The research of deep foundation pit in our country is still lacking, and the research on deep foundation pit of loess is relatively less, and the study of deep foundation pit of loess is of great significance in this paper. Based on the study of Xi'an loess, the foundation pit with single layer and multi-layer structure is selected. The failure mode of loess foundation pit slope is studied by using finite element software, and the instability mechanism of loess foundation pit slope is analyzed to guide the selection of supporting scheme for loess deep foundation pit. According to a practical project in Xi'an city, the foundation pit with soil filling and loess composite structure is analyzed, and three kinds of supporting structures are preliminarily designed for the deep foundation pit of the loess. Three kinds of supporting schemes are analyzed by finite element method. Considering many factors, the composite soil nailing wall is selected as the optimal scheme. After selecting the optimal supporting scheme, through the further optimization, we strive to reduce the project cost and save the resources under the condition of safety. Finally, the feasibility of the optimization scheme is verified by comparing the field monitoring data with the results of finite element simulation. The main conclusions are as follows: 1) for the foundation pit with a wide distribution of different loess combinations in Xi'an, combined with some practical projects, the reasonable parameters are selected: through the finite element three-dimensional simulation, It is concluded that the failure mode of loess combination geology is mainly divided into sloping, sliding, sitting and partial collapse. 2) A stratum of Xi'an is selected as the foundation pit of soil filling and loess combination structure, and the anchor-pull single row pile is designed preliminarily. Anchor-pull double row pile and composite soil nailing wall three kinds of supporting structure; The finite element analysis is adopted and the influence of the three supporting schemes on the displacement, safety factor, engineering cost, construction difficulty and surrounding environment is comprehensively considered. The composite soil nailing wall supporting structure is determined as the optimal scheme. 3) the further optimization of the composite soil nailing wall supporting structure is mainly to reduce the slope ratio, increase the horizontal and vertical spacing of the composite soil nailing, and reduce the diameter of the reinforcing bar. By reducing the length of soil nailing and anchor rod, six hundred and fifteen thousand six hundred yuan was saved on the original basis. Compared with the field monitoring data, the feasibility of the optimization scheme is also verified.
【学位授予单位】：西安工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU444;TU473

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