Optimum Design Study Of Retaining Piles Structure With Interior Bracing

Excavation in foundation pits is a traditional topics with which we often meet in civil engineering. It is a complex technical engineering which possesses experience and risk.With the deepgoing of the research on braced excavations and the phenomenas of prematureance and conservative frequently occurred in design practice of braced excavations,the optimum design for retaining structures has been a problem to numerous specialized technical staff.For discussing the internal action mechanism about the topic mentioned above,the thesis has finished the following works through combining the research of retaining piles structure with interior bracing by the author's unit since 2004.Firstly,it has reviewed and analyzed the optimum design course of braced excavations,it has also summarized the optimum principle and ways(gradations) of braced excavations.The research direction and development of selecting objective function,establishing optimum model and design method etc.are generalized.Secondly,based on analyzing the mechanical charactristic and optimum design room of retaining piles structures with interior bracing,the paper has choosed the design variable X and the objective function f(X) on the basis of optimum criterion called full-stress design,then the mathematics model of optimum design for the location(joint) of retaining piles structures with interior bracing has been built,a variety of gaining mathods and calculating formulas of the allowable resisting curve stressσ_m and the allowable retaining axial pressure stressσ_c are derived,then the three gaining methods aboutσ_m andσ_c are compared and discussed each other. Moreover,the complex stress state of waling on the locations(joints) of retaining piles-interior bracing and the influence of internal force and deformation & displacement by the waling above are simply analyzed and discussed.Finally,the paper affords an application example of the optimum design for the retaining structure in soft soil areas,which could confirm the accuracy and effectivity of the method of optimum design.The paper firstly proposes the maths model of optimum design for the locations(joints)of retaining piles-interior bracing in retaining piles structures with bracing.The concept ofσ_m andσ_c is offered too, as well as the nature and physical means ofσ_m andσ_c is designated.The optimum design model mentioned above on the locations(joints) of retaining piles-interior bracing belongs to partial optimum solution,it' s mechanical concept is distinct,it is also simple and practical.It could be used for reference in optimum design of comparable excavations.