桩锚支护下叙福花苑基坑稳定性及受力变形分析

发布时间：2018-08-06 10:59

【摘要】：随着城市建设的发展,基坑工程越来越多。基坑支护结构通常作为临时性结构,相比永久性结构,安全储备较小,而基坑工程一般位于城市,周边有各种建筑物、管线、道路等,一旦失事就会造成生命财产的重大损失。因此保证基坑开挖的安全,避免工程事故尤为重要。本文以东莞市叙福花苑基坑支护工程为背景,结合基坑开挖的施工过程,先通过理正深基坑设计软件计算了每种工况下的内力并根据内力值进行配筋计算,对基坑还进行了整体稳定性验算、抗倾覆稳定性验算和抗隆起验算。又基于GeoStudio有限元软件的三个模块进行研究:首先,利用SIGMA/W模块对叙福花苑基坑的施工过程进行模拟,分析了基坑与支护结构在分步开挖过程中的变形特性和土体的应力应变特征。其次,利用QUAKE/W模块分析了本基坑在水平地震作用下的动力响应,从坡顶到桩底设置11个历史记录点,分析其位移、速度、加速度的变化规律。最后,利用SLOPE/W模块计算了开挖过程中的安全系数,探讨了土体c、?值的影响,又用拟静力法计算了开挖后的基坑在水平地震(6度设防烈度)下的安全系数,分析了土钉长度变化对安全系数的影响,最后考虑动应力的影响,得到了基坑的安全系数时程曲线。通过基坑施工过程的数值模拟,发现支护桩的水平位移曲线呈“两头小,中间大”的形状,朝基坑内侧移动,锚索平均每增加50kN的锁定力,桩顶的水平位移约减小1.5mm,在实际工程中,应根据所要求的位移控制值来选择合适的锁定力。通过分析土体的应力应变,发现基坑角部和桩底附近的土体容易进入塑性状态。为减小塑性区的范围,降低安全隐患,做同类型的支护设计时,要保证支护桩有足够的入土深度,施工时要注意被动区土体的加固与监测。通过理正的验算与有限元软件安全系数的分析可知,工程设计是满足使用要求的。本文的分析模拟过程与结果也为同类型工程问题的合理设计提供了一定的参考。
[Abstract]:With the development of urban construction, foundation pit engineering is more and more. The foundation pit support structure is usually used as a temporary structure, compared with the permanent structure, the safety reserve is smaller, while the foundation pit works are generally located in the city, there are a variety of buildings, pipelines, roads and so on, once the accident will cause great loss of life and property. Therefore, it is very important to ensure the safety of excavation and avoid engineering accidents. Based on the foundation pit support project of Xufuhuayuan in Dongguan city and the construction process of the excavation, the internal force under each working condition is calculated by the design software of Lizheng deep foundation pit and the reinforcement is calculated according to the internal force value. The whole stability check calculation, the anti-overturning stability check calculation and the anti-uplift check calculation are also carried out for the foundation pit. Three modules of finite element software based on GeoStudio are studied. Firstly, the construction process of Xufuhuayuan foundation pit is simulated by using SIGMA/W module. The deformation characteristics of foundation pit and support structure and the stress-strain characteristics of soil are analyzed. Secondly, the dynamic response of the foundation pit under horizontal earthquake is analyzed by using QUAKE/W module. Eleven historical record points are set up from the top of the slope to the bottom of the pile to analyze the variation law of displacement, velocity and acceleration. Finally, the safety factor during excavation is calculated by using SLOPE/W module. By using the pseudostatic method, the safety factor of the excavated foundation pit under the horizontal earthquake (6 degree fortification intensity) is calculated, and the influence of the change of soil nail length on the safety factor is analyzed. Finally, the influence of dynamic stress is considered. The time history curve of safety factor of foundation pit is obtained. Through the numerical simulation of foundation pit construction process, it is found that the horizontal displacement curve of the supporting pile is in the shape of "two small ends with a large middle", moving towards the inside of the foundation pit, and the anchor cable increases the locking force of 50kN on average. The horizontal displacement of the pile top is reduced by about 1.5 mm. In practical engineering, the appropriate locking force should be selected according to the required displacement control value. By analyzing the stress and strain of soil, it is found that the soil around the corner of foundation pit and pile bottom is easy to enter into plastic state. In order to reduce the scope of plastic zone and reduce the hidden danger of safety, it is necessary to ensure that the supporting pile has enough depth in the design of the same type of support, and pay attention to the reinforcement and monitoring of the soil in the passive zone during construction. Through checking calculation and analyzing safety factor of finite element software, it can be seen that the engineering design meets the requirement of application. The simulation process and results in this paper also provide a reference for the reasonable design of the same type of engineering problems.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU470

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