Stability And Reliability Analysis Of Composite Soil-nailed Wall

On the base of soil nailing structure, as a new kind of retaining and protecting structure for foundation excavation, composite retaining and protecting structure has got rapid development in the recent years. According to the site conditions, this technology combines soil nailing wall with deep-mixed pile ,jet grouted pile, mini pile, steel-tube soil nail or prestressed anchor, thus forms a composite retaining and protecting structure for foundation excavation, this technology overcomes the flaw of traditional soil nail supporting technology, namely can't control the deformation of slope, so it has many advantages, such an safety, reliability, less cost, low time-consuming, and is gaining a wider and wider range of application. Therefore, it is necessary to carry on the stability analysis of the composite soil nail supporting slope. The major works of this article are as follows:(1) Discussed the composite soil nailing support technical formation, development and research status, and summarized the composite soil nailing support technical advantage and application prospect, analyzed the composite soil nailing support technology at present research work shortcomings.(2) Based on the limit equilibrium theory and the slice analysis method for the stability of soil-nail braced supporting structure, according to the composite soil-nailed support structure and the stability factor of safety relationship for parabolic assumption slip surface, and use the geometry relationship with the method of circular, the search model of the most dangerous slip surface were set up and solution formula of stability safety factor is derived so as to provide theoretical basis for design of composite soil-nailed wall. The function relations among the geometrical controlling parameters of sliding surface and the stability safety factor are deduced. Calculation of integral stability of a building foundation pit with the composite soil-nailed braced structure in Lanzhou has been carried out by using the genetic algorithms.(3) According to the characteristics of composite soil nailing supporting techonology, based on the full analysis of working mechanism of all parts of the composite soil nailing supporting structure; Using probability analysis based on reliability analysis method to analyze the structure of composite soil nailing support stability. For each slip surface given first in reliability, the structural reliability calculation model is suggested by slide surface langrange multiplier multiplier. The bonding strength and clustering analysis of internal friction angle the influence of reliability indexes. Finally, slope reliability index search model is established by genetic algorithm, and through engineering examples calculation and analysis which verify the reliability calculation method of rationality.