【作者】 陈伟；

【导师】 黄强；

【作者基本信息】 中国建筑科学研究院 ， 岩土工程， 2014， 博士

【摘要】 随着国内高层建筑的发展和地下空间的开发,基坑工程也朝着深、大的方向发展。当前,对于这些深、大基坑提出的“挡土”和“止水”功能要求,国内普遍使用现浇的地下连续墙和钻孔灌注桩这两种围护结构,对保证深基坑工程的安全起了重要作用。连锁空心方桩地下连排墙是一种全新的基坑支护型式。预应力混凝土空心方桩(以下简称空心方桩)具有单桩承载力高、抗弯刚度大、施工速度快的特点,其已经在桩基工程中得到大量应用,但将空心方桩应用在深基坑工程,尤其是仅用单一桩型就能同时解决基坑工程的“挡土”和“止水”问题的成功应用还是空白,因此研究如何将空心方桩用于深基坑工程是很有现实意义和工程应用价值的。本文立足于空心方桩的现有研究成果和标准,根据深基坑工程的特点,对·原来普遍用于桩基工程的空心方桩加以改造,研究由此产生的一系列问题,使改造后的空心方桩能够适应深基坑工程的要求,最终形成可以应用于深基坑工程的空心方桩支护成套技术。本文针对空心方桩的桩型改造、承载力和抗弯刚度、生产工艺、连锁成墙施工工艺、设计计算等方面进行了系列理论研究,开发了配套的连锁空心方桩地下连排墙设计软件,在昆明市进行了工程现场试验研究,还将连锁空心方桩地下连排墙支护和已经完工基坑工程的钻孔灌注桩支护进行了对比分析,取得了一些创新的成果。研究的主要内容、成果和方法如下：1、本文详细地研究了基坑支护空心方桩的截面设计与变化、承载力和抗弯刚度参数,并将空心方桩与实心圆桩的承载力和抗弯刚度进行了对比分析,开发出了新的基坑支护空心方桩类型。论文将空心方桩连锁成墙和现有基坑工程的钻孔灌注加高压旋喷桩／深层搅拌桩进行了技术经济对比分析,为钻孔灌注桩加止水帷幕支护的基坑工程提供了一种新的用单一空心方桩支护的选择。2、本文研究了基坑支护空心方桩的生产工艺、连锁成墙施工工艺,重点研究了其中的一系列难点和关键技术,总结出了一套完整的基坑支护空心方桩的工厂生产和现场连锁成墙施工工艺。3、本文提出了连锁空心方桩地下连排墙的等效设计法,该方法简便易行,便于工程应用。重点研究了连锁空心方桩地下连排墙的三维分析,开发了配套的二维和三维连锁空心方桩地下连排墙设计计算软件。4、本文进行了连锁空心方桩地下连排墙用于实际深基坑工程的试验,设计、施工了工程试验段,进行了相应的监测工作,对监测数据进行了反分析,总结了试验段的研究工作并形成一系列重要结论。通过上述研究,从硬件和软件两方面形成了连锁空心方桩地下连排墙基坑支护成套技术。研究还表明,连锁空心方桩地下连排墙具有很多优势,并有很好的市场前景。本文在最后提出连锁空心方桩地下连排墙作为基坑支护新体系需要进一步研究的重要问题。更多还原

【Abstract】 With the development of the high-rise buildings and underground spaces, the excavation engineering also developed towards deeper depth and larger area. At present, the function request of retaining soil and sealing water of excavation is accomplished by the widespread use of cast-in-place bored pile and diaphragm which played an important role to ensure the safety of the foundation pit. The platoon-oriented wall made by chain prestressed spun concrete square pile is a new type of retaining and protection structure for building foundation excavations.As a new type of pile, the prestressed spun concrete square pile (simply named PS hereinafter) has the characteristics of high bearing capacity, high bending stiffness and fast construction speed. Although PS has been widely used in pile foundation engineering, it is completely absent to use PS in deep excavation engineering; especially the application of using a single type of pile to solve the problems of retaining soil and sealing water at the same time is still vacant so far. So, the research on how to apply PS to deep foundation pit engineering has a very practical significance and engineering application value.Based on the existing research results and relevant standards, PS that was widely used in pile foundation engineering was transformed according to the characteristics of deep excavation. Moreover, a series of problems have been researched so that the transformed PS can meet the requirements of deep excavation engineering. Finally, the complete techniques of PS for deep foundation pit can come into being.Therefore, the theoretical studies such as pile type transformation, bearing capacity and bending rigidity, manufacture method, construction technology, design calculation method and other aspects have been made in this dissertation. Moreover, the matching design software of PS platoon-oriented wall has been developed and the field experimental research has been finished in an engineering in Kunming City. In addition, there is a comparision between PS platoon-oriented wall and the cast-in-place bored piles that existed in some completed foundation excavations. As a result, the author makes some innovative achievements. The following shows the main contents, results and methods of the research:(1). In this dissertation, the section design and change of PS, the parameter of bearing capacity and bending rigidity were calculated and studied in details. Furthermore, the comparision of bearing capacity and bending rigidity between PS and solid circular pile were analyzed in details. Naturally, PS for deep excavation has been developed as a new type of pile. Moreover, the comparison of technology and economy indicators between PS platoon-oriented wall and the bored piles with jet grouting piles or mixing piles of some completed deep excavation engineerings has been drawed. As a result, the author put forward a new choice using single type of PS platoon-oriented wall for those engineerings using the combination of bored piles and water sealing curtain.(2). The author also researched the detailed manufacture method, construction technology for PS platoon-oriented wall and so on, especially studies a series of difficult problem and key technology among them, and summarizes a complete set technology of production and site construction of PS platoon-oriented wall.(3). Moreover, the equivalent algorithm of design method of PS platoon-oriented wall for deep excavation was researched and put forward. This method is simple and convenient for engineering applications. The3D analysis method of PS platoon-oriented wall retaining structure has been researched as a key point. In addition, the author has also developed a matching2D and3D software for design of PS platoon-oriented wall retaining structure.(4). PS platoon-oriented wall has been applied to actual deep excavation engineering for experiment and test. The experimental segment wall was designed and constructed and the relevant test work has been finished. Furthermore, the author has made back-analysis based on the test data and summarized the research work of experimental segment wall. Ultimately, a series of important conclusions were put forward in this paper.It can be concluded that the complete set technology of PS platoon-oriented wall for excavation retaining has come into being not only with hardware but also with software. It shows PS platoon-oriented wall has many advantages and bright market prospect based on the above research. However, as a kind of new products, PS platoon-oriented wall still needs many further research and development, so some important problems and topics are listed in the final part of the dissertation.更多还原