坑中坑基坑支护结构工作性状研究

发布时间：2018-01-08 14:30

本文关键词：坑中坑基坑支护结构工作性状研究　出处：《扬州大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着经济的发展和城市人口的剧增,城市建设步伐日趋加快。大批高层建筑、地铁、地下商场、车库等大规模地下空间的建设都出现了超深基坑。为了满足基础结构、电梯井或地下室功能等的需要,常常要在大基坑内部进行二次或多次开挖,这就出现了二级以及多级基坑现象——坑中坑。基坑工程往往具有事故多发的特征,特别是坑中坑基坑的安全问题更应加以重视,但是,国内外针对坑中坑基坑的理论研究还较少。本文以某一典型的坑中坑基坑为研究对象,先用常规的计算方法进行设计,然后利用abaqus有限元软件进行了二、三维模拟,采用强度折减与有限元相结合的方法对内外坑相互间的影响进行了弹塑性分析。并在已有计算模型的基础上,对比分析了不同平台宽度、内坑深度对坑中坑基坑等效塑性应变、被动土压力、连续墙水平位移、安全系数的影响。最后,分别用四种方法计算坑中坑基坑的外坑被动土压力。通过研究,得到的主要结论有： (1)外坑支护计算时必须考虑内坑对外坑的影响,内坑处于2.0-2.7倍内坑开挖深度范围内,基坑设计时须对外坑的被动土压力进行折减；处于4.5-5倍内坑开挖深度范围内,仍须考虑内坑对整体安全系数的影响；在4.5-5倍内坑开挖深度范围外,可以将内、外坑作单独设计。 (2)在内坑的影响范围内,内坑对整体稳定性影响程度大于被动土压力影响程度,内坑深度对外坑连续墙变形的影响程度大于平台宽度对外坑连续墙变形的影响程度。 (3)微分法和有限元法计算坑中坑被动土压力较为合适。
[Abstract]:With the development of economy and city population growth, the pace of city construction is accelerating. A large number of high-rise buildings, subway, underground garage and other large-scale shopping malls, the construction of underground space have appeared in ultra deep pit. In order to meet the basic needs of elevator well structure, function or basement, often have two or more times in the excavation of large the pit inside, which appeared in the two stage and multi-stage excavation phenomenon of pit in pit excavation engineering. Often has the characteristics of accidents, especially the safety problems of pit in pit excavation should be more attention, but the domestic and foreign theoretical research for the pit in pit excavation is less.
This paper takes a typical pit in pit excavation as the research object, first use the calculation method of conventional design, then two, by using the finite element software ABAQUS simulation, using strength reduction method combined with finite element of influence between inside and outside the pit for the elasto-plastic analysis and calculation basis. In the existing model, comparative analysis of the different width of the platform, the pit depth of pit in pit of equivalent plastic strain, passive earth pressure, horizontal displacement of diaphragm wall, affecting the safety coefficient. Finally, respectively, outside the pit pit of the passive earth pressure is computed using four methods.
Through the study, the main conclusions are as follows:
(1) effects must be considered in the pit pit outside pit support method, the pit in pit excavation depth is 2.0-2.7 times the range, to foreign pit design of passive earth pressure reduction; at 4.5-5 times the pit excavation depth range, we still have to consider the pit on the overall effect of all safety coefficient in 4.5-5 times; the pit excavation depth, can be in a separate external pit design.
(2) the influence degree of the inner pit on the overall stability is greater than that of the passive earth pressure, and the influence of the pit depth on the diaphragm wall deformation is greater than that of the platform width.
(3) the differential method and the finite element method are suitable for calculating the pit pressure in the pit.

【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU470

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