Design And Application Of The Retaining And Protection For Deep Foundation Excavation

Abstract:The design of the retaining and protection for deep foundation excavation is a very difficult problem in the construction of high-rise and super high-rise buildings. It is bound up with the quality, the progress, the economic benefits of the project and the safety of construction whether the design is scientifically and reasonable. So it is a very important subject.It is also a complex synthetic geotechnical difficult problem. It involves not only the geographical environment, the stratum characteristics of the building site, geotechnical physical and mechanics parameters, typical strength and stabilization problem, deformation problem, but also the CO. effect of soil and support structure.This paper explores the principles to be followed in the design of the retaining and protection for deep foundation excavation, including the various conditions that must be meet under ultimate limit state and serviceability limit state.It is also needed the computed result to be checked,including the checking computations of the stability of foundation excavation, the surroundings around foundation excavation, the anti-heave stability, the supporting structure deformation,the anti-seepage stability of foundation excavation and the bottom inrushing stability combining with the practical engineering case.The main methods of designing include the conventional method, the elastics method and the numerical analysis method. This paper explores the theories and the existing problems of these methods. It is also discusses on the calculation and application of two methods in the design of anchor piles bracing structure.(1) This paper discusses seven theories of the earth pressure of deep foundation excavation, and it is also derive the calculation formulas in the design of anchor piles bracing structure of deep foundation excavation.(2)It is discussed how to choose the type of anchor piles bracing structure and the structure system of deep foundation excavation in this paper, including the calculation methods of horizontal load and horizontal resisting force, cantilever supporting structure, multiple fulcrum supporting structure, structure inner force, sectional bearing capacity and calculation of anchor etc.(3) This paper expound the mechanical property and advantages of the design of anchor piles bracing structure, through discussing its principle of operation.(4)This paper chooses the classic method (conventional method) to compute internal force,deformation and fulcrum force of structure.It also checks the stability of foundation pit according to the specification requirements.(5)The layout of engineering drainage system,the techniques of engineering monitoring and the key points for construction of anchor piles bracing structure are introduced combining with the practical engineering case. The actual results prove that the implementation of these measures ensure the foundation pit engineering construction(6) This paper ummarize the advantages and disadvantages of the design of anchor piles bracing structure,it also shows applicable conditions of this structure, so it has certain instructive effect on how to choose the supporting method and design for the similar foundation pit.