海口某深基坑开挖支护设计及数值模拟分析

发布时间：2018-05-30 07:25

本文选题：深基坑 + 支护设计　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：高层建筑、市政交通工程、水利水电工程等都要解决深基坑问题而且基坑工程造价高、工期长、难度大,因此合理设计支护结构,保障基坑的安全稳定一直是重要课题。如何预测基坑在施工过程中的变形量,以确保基坑自身和周围环境的安全,也是其中的重点,数值模拟是现阶段解决这个问题的有效途径。本文首先使用启明星软件对海口塔基坑进行了支护设计以及一般稳定性计算。然后使用有限元软件PLAXIS,模拟分析了该工程支护施工分布开挖的全过程。在分析中,分别采用土体本构模型摩尔—库伦模型以及土体硬化模型,同时采用板单元模拟支护桩与地下连续墙组成的围护结构,以点对点锚杆结合土工格栅模拟支撑锚杆,划分不同工况模拟分步施工,最后得出每一工况下基坑内力、地面沉降和坑底回弹。本文主要工作成果如下:(1)使用启明星软件计算海口塔南塔基坑整体稳定性、坑底抗隆起安全系数以及墙底抗隆起安全系数,求得的所有安全系数都满足规范中的要求,因此可以认为支护方案是安全的。(2)文中对于本构模型参数的选取,参考海口地区相关实验研究资料得:土体的弹性模量E取5倍E_(S1-2),土体硬化模型中的固结模量E_(oed)、割线模量E_(50)与卸载再加载模E_(ur)的值都偏小与一般值。(3)HS模型模拟结果地表沉降表现为凹槽型,符合工程实际经验。HS模型与MC模型中围护结构的侧向变形呈现出抛物线形,在开挖坑底处变形较大。(4)本文通过两种本构模型在基坑内力、地面沉降、坑底回弹和土体水平位移方面模拟结果的对比分析,总结出HS模型与MC模型的优缺点及各自适用的情况。
[Abstract]:High-rise buildings, municipal transportation projects, water conservancy and hydropower projects all have to solve the problem of deep foundation pit, and the foundation pit project cost is high, the construction period is long, difficult, so reasonable design of supporting structure to ensure the safety and stability of foundation pit has been an important issue. How to predict the deformation of foundation pit in the construction process to ensure the safety of the foundation pit itself and the surrounding environment is also the key point. Numerical simulation is an effective way to solve this problem at this stage. In this paper, the support design and general stability calculation of Haikou Pagoda foundation pit are carried out by using Qixing software. Then using finite element software PLAXIS, the whole process of distributed excavation is simulated and analyzed. In the analysis, the soil constitutive model Moore Coulomb model and the soil hardening model are adopted respectively. At the same time, the plate element is used to simulate the retaining structure composed of supporting pile and underground continuous wall, and the point-to-point anchor bar combined with geogrid is used to simulate the supporting anchor rod. Finally, the internal force of foundation pit, the ground subsidence and the rebound of pit bottom are obtained under different working conditions. The main results of this paper are as follows: (1) the overall stability of the foundation pit of the tower in Haikou, the uplift resistance of the bottom of the pit and the safety factor of the uplift at the bottom of the wall are calculated by using the Qi-Ming software. All the safety factors obtained meet the requirements of the code. Therefore, it can be considered that the support scheme is safe in the selection of constitutive model parameters in the paper. Referring to the relevant experimental data of Haikou area, it is found that the elastic modulus E of the soil is 5 times E _ S _ (1-2), the consolidation modulus of the soil hardening model is E _ T _ (50), the Secant modulus is E _ (50) and the unloading reloading model is Etiururg). The simulation results of the model are smaller than those of the general value. The surface subsidence is of groove type. In accordance with the practical engineering experience. HS model and MC model, the lateral deformation of the retaining structure presents parabola shape, and the deformation at the bottom of the excavation pit is larger. (4) in this paper, two constitutive models are used to analyze the internal force and ground settlement of the foundation pit. Based on the comparative analysis of the simulation results of bottom springback and horizontal displacement of soil mass, the advantages and disadvantages of HS model and MC model and their respective applicable conditions are summarized.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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