The Complete Set Technology Research On Platoon-oriented Wall Of Chain Prestressed Spun Concrete Square Pile For Excavation

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.