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1、河北工业大学硕士学位论文大型深基坑支护方案优化设计与数值模拟姓名：吴松申请学位级别：硕士专业：结构工程指导教师：窦远明20081101河北工业大学硕士学位论文i大型深基坑支护方案优化设计与数值模拟大型深基坑支护方案优化设计与数值模拟摘摘 要要随着我国国民经济的飞速发展，城市化进程不断加快，同世界所有发达和发展中国家一样，土地资源紧张的矛盾也日益突出，城市建设向高空、向地下争取建筑物空间己成为一个发展趋势。由此而产生了大量的基坑工程，且规模和深度不断加大，平面尺寸已达两三百米，深度达数十米。基坑支护设计与施工既是我国各大城市基本建设工程的重要问题 ，又是岩土工程中比较复杂的问题。因此，加强对基坑
2、支护设计计算理论及数值模拟的研究 ，提高对基坑工程实践的指导就显得尤为重要。本文主要工作与结论包括：1介绍了深基坑支护设计理论，包括深基坑支护结构常用计算方法、深基坑工程中的土压力问题等，对各种方法进行了分析与对比，归纳总结了各自优缺点;2介绍了价值工程理论和层次分析法，利用这两种理论对基坑支护方案进行了优化设计，最终确定了支护方案。3本文所用的二维有限元分析方法能基本真实地模拟基坑所在场地和结构本身的空间作用，能有效地反映基坑开挖、土体卸载、锚杆安装过程对基坑变形的影响，表明该方法具有很强的实用性和拓展性。4在模型的选取上， 采用了先进的 HS 模型， 由于 HS 模型很好的考虑了卸荷的特性
3、， HS模型在卸荷时表现得更硬，而 MC 模型只有一个单一刚度，实际卸荷模量要比变形模量大，而 HS 模型考虑了卸荷，采用先进的 HS 模型可以得到较好的模拟结果。5对基坑工程在施工期间所得 8 个监测点的数据进行了详细分析，绘出了不同监测点所得基坑水平位移随时间变化的曲线，并通过它们的对比，得出监测点 2、3、4 三点处基坑水平位移变化最大，建议此处施工时应减缓施工速度，并加强这三点内侧的支护结构，如适当提高支撑刚度等；6通过有限元数值模拟所得基坑监测点的最终水平位移普遍小于工程实地监测数据，通过分析比较得出结论认为，除了基坑建模模拟本身存在的误差外，基坑数值模拟时没有考虑周边环境的影响是造
4、成两种结果产生一定差别的主要原因。关键词关键词：基坑，支护结构，有限元，变形，地表沉降，数值分析大型深基坑支护方案优化设计与数值模拟iiOPTIMIZATIONOPTIMIZATIONOPTIMIZATIONOPTIMIZATION DESIGNDESIGNDESIGNDESIGN ANDANDANDAND NUMERICALNUMERICALNUMERICALNUMERICAL SIMULATIONSIMULATIONSIMULATIONSIMULATION OFOFOFOF DEEPDEEPDEEPDEEP FOUNDATIONFOUNDATIONFOUNDATIONFOUNDATION
5、PITPITPITPIT SUPPORTINGSUPPORTINGSUPPORTINGSUPPORTING SCHEMESCHEMESCHEMESCHEMEABSTRACTABSTRACTABSTRACTABSTRACTWith the rapid development of Chinas national economy, the process of urbanization is Accelerating.Withallthe worlds developed and developing countries, the strain on the resources of land c
6、onflicts have become increasingly prominent, urban construction to high-altitude, to the ground floor of the building for space has become a trend. Resulting in a lot of foundation pit and the size and depth is increasing, the plane has reached the size of two or three hundred meters, a depth of ten
7、s.foundation pit supporting design and construction is not only an important issues of Chinas major cities infrastructure projects, but a geotechnical engineering problems.So,It is important to strengthen the design calculation method offoundation pit supporting design and numerical simulation study
8、,to improve the practice guidance onfoundation pit.The main contents and results are as following：1 The Design theory of deepfoundation pit supporting areintroduced，including thecommon calculation method of the deepfoundation pit supporting structure，the problem ofearth pressure on deepfoundation pi
9、t.a variety of methods are analyzed and compared, their strengths and weaknesses are summarized;2Value engineering theory and analytic hierarchy process areintroduced，thefoundationpit supporting scheme are optimized by use of these two theories，and the scheme of support arefinalized. 3 Two dimension
10、al finite element method adoped in this paper can actually simulate the influence ofthe process of excavating,unloading of soil mass,Installation of anchor.And indicated that this method is of high practicability and validity. 4 Adopting advanced Hardening Soil Model. Because unloading property is s
11、pecially considered in Hardening Soil Model, Hardening Soil Model has better rigidity compared to MOHR-COULOMB Model,which has only one rigidity parameter.Actually,unloading modulus is larger than deformation modulus.a better result of simulation results could be obtained by adopting Hardening Soil
12、Model. 5 A detailed analysis about the 16 data of construction monitoringfrom thecase of deepfoundation pit are carried out ，the curve varying unit vector of horizontal displacement offoundation pit from different monitoring points are drawed.then a comparative analys is madeand the result is that n
13、umber 2、3、4have bigger values than others. Advises are made that河北工业大学硕士学位论文iiireducing the speed in those dangerous areas and strengthening supporting in those three areas，such asproperly increases supporting stiffness. 6 It indicates that the final values of horizontal displacement from simulating
14、 the case of deep excavation are smaller than the data of construction monitoring prevalently.The most important factoristhat without regarding to circumstance around the deepfoundation pit besides the error of building model.KEY WORDS:foundation pit, supporting structure, finite element, deformatio
15、n, ground settlement, numerical analysis河北工业大学硕士学位论文vii符号说明符号说明、作用于土条 i 的自重和地面地下荷载。iWiQ土条 i 圆弧破坏面切线与水平面的夹角。i土条 i 的宽度。i土条 i 圆弧破坏面所处第 j 层土的内摩擦角。j土条 i 圆弧破坏面所处第 j 层土的粘聚力。jC破坏面上第 k 排土钉的最大抗力。kR第 k 排土钉轴线与该处破坏面切线之间的夹角。k第 k 排土钉的水平间距。hkS土钉倾角。土钉长度中点所处深度位置上的侧压力。p土钉长度中点所处深度位置上由支护土体自重引起的侧压力。1p地表均布荷载引起的侧压力。qp、弹性应变
16、和塑性应变。ep、弹性应变增量和塑性应变增量。()e()p、总应变和总的应变增量。d E杨氏弹性模量（MPa）。泊松比。c粘聚力（KPa）。内摩擦角（o）。剪胀角（o）。1第一章绪 论第一章绪 论1-11-11-11-1课题背景及研究意义课题背景及研究意义随着我国国民经济的飞速发展，城市化进程不断加快，同世界所有发达和发展中国家一样，土地资源紧张的矛盾也日益突出，因此，城市建设向高空、向地下争取建筑物空间己成为一个发展趋势。目前各类用途的地下空间已在世界各大城市中得到开发利用，诸如高层建筑地下室、地下铁道及地下车站、地下停车场、地下街道、地下仓库、地下民防工事以及多种地下民用和工业设施等。按照国际标准，城市人口密度大于每平方公里 2 万人属于拥挤情况，我国上海城市人口平均密度为每平方公里 4 万人，局部地区每平方公里 16 万人，北京人口平均密度为每平方公里 2.7万人，均处于超饱和状态，位于世界人口高密度之首1。
