【作者】 吴锐；

【导师】 臧德胜；

【作者基本信息】 合肥工业大学 ， 市政工程， 2009， 硕士

【摘要】 随着城市化建设的不断发展,基坑工程不仅数量增多,而且向更大、更深方向发展。大量基坑工程集中在市区,施工场地狭小,施工条件复杂,如何减小基坑开挖对周围建(构)筑物、道路和各种市政设施的影响,发展基坑开挖扰动环境稳定控制理论和方法将引起人们进一步的关心和重视。本文研究排桩的优化设计问题,其主要方面如下:(1)当土的力学性能比较差时,咬合桩是一种非常好的支护结构,对咬合桩作为永久结构使用的咬合桩复合结构设计理论和方法进行了研究。同时,研究了不同搭配形式咬合桩作为主体结构使用的可行性,认为荤荤搭配的咬合桩可以作为主体结构一部分使用,但荤素搭配的咬合桩作为主体结构一部分使用要控制素桩的裂缝发展。(2)当土质为粘性土时,应充分考虑土的拱效应,采用柱列式排桩进行支护。本文利用有限元软件ANSYS对桩后土拱效应进行二维数值分析与探讨,分析不同桩截面、不同桩间距、不同土体参数以及桩体位移等因素对桩后土拱效应的影响程度等问题。(3)结合排桩设计的解析法,进行抗滑桩与周围土体相互作用的三维数值模拟分析与探讨,分析桩与周围土体受力特性,桩和周围土体的变形与应力变化趋势。分析结果表明:抗滑桩的支挡作用,土拱效应是主要作用机理;粘聚力高的土体,有利于提高抗滑桩的加固效果,桩距增加会造成最大位移和桩土相对位移的增大,增加到一定程度会造成桩间土挤出量过大,从而使得抗滑桩支挡失效。(4)利用ANSYS二次开发技术,开发非线性的邓肯一张模型,采用不同的本构模型,邓肯—张模型和D-P模型,对粘性土中抗滑桩与周围土体相互作用的数值模拟,研究了不同土的本构关系对桩间土拱的影响。本文仅对在不同土质中如何选择合理的基坑支护方法做初步的探讨,要得出更完善的设计方法,还要做进一步的深入研究。研究结果和相关结论为完善基坑支护理论,以及为类似工程的设计提供依据和参考。更多还原

【Abstract】 With the development of the city capital construction, deep excavation pits not only increase, but also develop further. Large quantities of deep excavation pits engineering concentrate in the downtown, so the construction engineering has the special character as below: The first is construction field would be narrow and small. The second is construction has complicity condition and the third is construction engineering affects the roads and different kinds of municipal buildings nearby, etc. How to decrease the effects has become very important for people’s consideration. The paper deals with the optimization design of cantilever row piles retaining structure. The main aspect is as follow:(1) If the mechanic property of soil is bad, it’s better to use secant pile wall. The research on the theory and the design method of the secant pile wall composite Structure used as permanent structure is studied in the paper. At the same time, the paper discusses the feasibility of different secant pile wall used as permanent structure and includes that the hard /hard secant pile wall can be used as permanent structure and hard / firm as a part of permanent structure, the joints between secant pile wall and the exterior wall of the major structure are also presented.(2) As for clay soil, it is reasonable to use solider piles because of the existence of soil arching effect. The finite element analysis software package, ANSYS, is used to study soil arching effect of anti-slide pile, and the effects of factors on the behavior of soil arching effect such as pile spacing, properties of soil, interface of soil-pile and the movement of pile are discussed in detail in this paper.(3)Combined with the analysis of anti-sliding pile , analyzed the interaction of anti-sliding pile with the surrounding soil by three-dimensional numerical modeling, analyzed the characters of anti-sliding pile and surrounding soil, the deformation trend of anti-sliding pile and surrounding soil and stress trend . The results showed that: the main influence factors are the sustentation effect of anti-sliding pile and the earth-arch effect. High cohesion soil will increase anti-sliding piles’reinforcement. The increase of pile spacing will increase the largest displacement and the relative displacement between the pile and earth, arise excess soil that between piles being extruded and make the anti-sliding pile invalid when the extent exceeds the requirement.(4) Developed the Duncan-chang constitutive model in ANSYS software by means of the secondary developing technology of ANSYS. Using different soil constitutive models including the Duncan-chang constitutive model, Druker-Prager elastoplastic model, the paper analyzed the interaction of anti-sliding pile with the surrounding soil in clay soil by numerical modeling in order to obtain the influence of different soil constitutive models to the earth-arch effect between piles.This paper is just a preliminary study on how to choose the suitable supporting structure of pit, to develop a perfect design method, there is still a lot of further work to do. The results of research and relational conclusion will perfect the analysis theory of the pit support structure, and provide references for the designs of similar engineering projects.更多还原