文档介绍：摘要
本文以兖矿集团大陆机械有限公司某铸造厂房内部增设大型淬火深基坑工程为研究对象,对深基坑开挖进行理论分析和施工研究。由于基坑整体开挖最深达 20 米,且位于厂房内部,受到厂房的高度限制,紧邻厂房基础,无放坡距离且需要严格控制水平位移和和沉降,所以开挖支护难度是比较大的,因此采用桩锚支护结构。由于影响基坑开挖支护的的因素多种多样,进行现场及室内试验研究费用大,试验过程复杂,且加载条件、边界条件难以实现,影响结果的不稳定性因素较多。与现场及室内试验研究相比, 数值模拟方法费用小,具有很大的灵活性并能模拟各种复杂的边界条件,在缺少相关工程经验及现场或室内试验研究的情况下进行数值模拟是非常必要的。
本文以 FLAC3D 程序作为软件平台,结合兖矿集团大陆机械有限公司某铸造厂房内部深基坑工程实例,考虑土体与结构的相互作用,建立土体与结构的三维数值模型, 确定基坑的开挖支护步骤,模拟分步开挖支护过程,从整体上分析支护结构与周围土体的应力和位移。
结果表明:(1)每步开挖形成的水平位移曲线变化规律基本相似,均呈现先增大后减小的抛物线曲线规律,且基坑坑壁同一深度的水平位移变形随着开挖深度增大表现为增大的趋势,基坑最大的变形位置也随着基坑开挖支护的进行而逐渐降低;(2)每步开挖形成的沉降曲线变化规律基本相似,均呈现先增大后减小的抛物线曲线规律,且均逐趋于定值;(3)各步开挖支护后坑底的隆起曲线分布规律基本相似,且随着开挖深度的增大,坑底的隆起也逐渐加大;(4)随着基坑的开挖,锚杆逐渐发挥其作用,其承受的拉力也越来越大,开挖结束后,各层锚杆的轴力分布趋势基本接近,均由自由端头部开始递减,且明显满足支护结构的安全性方面的要求。
本文的研究成果可为本工程及同类型的深基坑开挖支护分析研究提供一定理论依据和指导意见。
关键词:深基坑、开挖、支护结构、土压力、水平位移、地表沉降、坑底隆起、锚杆、沉入式预制桩
ABSTRACT
Research object of the paper is a large quenching deep foundation pit added in a certain casting workshop in continental machinery pany of Yanzhou mining group. Do theoretical analysis of excavation and research construction process of the deep foundation pit. The maximum excavation depth of the foundation pit located in workshop is 20m, excavation is limited by the height of workshop and its foundation. There is no step-slope distance. Additionally, horizontal displacement and settlement of soil shuold be controlled strictly. Precisely because of these limitation, excavation and support is relatively difficult. Therefore, pile-anchor retaining structure is uesd in the engineering. Factors that affect excavation and support of foundation pit are various; cost of field test and laboratory test is expensive; process of test plex; loading condition and boundary condition are hard to achieve. However, compared to field test and laboratory test, numerical simulation method cost less and could simulate plicated boundary conditions. Therefore, it is necessary to do numerical simulation without relevant engineering experience, field test or laboratory test.
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