Study Some Ploblems On Optimization Design Of Soil Nailed Wall In Foundation Pit Support

Soil nail wall technology is a kind of in-situ soil reinforcement technology, whichdeveloped and evoluted on the basis of anchorage techniques and reinforced soil technology.In the design, reinforcement is applied in undisturbed soil, and interaction with thesurrounding soil and rock. Compared to passive restraint mechanism of retaining, soil nailwall reflect an active constrained mechanism, greatly contribute to their lack of strength. Forcenturies, studiers exploring the role of soil-nailing wall in supporting mechanism、stabilityanalysis and soil nail forces regularity, but the designer often combined with the region’sstratigraphic characteristics and experience to design the program. Without standards, designsnow are generally seen in two types: first, upper soil nail long and lower short, the second theupper soil nails shorter and lower soil nails a little longer.On the basis of a large number of relevant literature, this article explains the relevantcharacteristics of the current excavation, and the current support forms of excavation, as wellas the conditions of using various types of support. Combining the example of Foundation pitof Dan Xuan Fang B phase I,explains that soil-nail wall support is the best form. Andaccordance with the standards two kinds of soil nail support are designed, both are passed bythe Lizheng software for deep Foundation pit.Traditional limit equilibrium analysis approach cannot explain the actual working stressof the supporting structure, finite element method not only simulate the excavation andsupporting, but also calculate the force of soil nails and displacement of the top. So, two kindsof soil nail support are simulated by MIDAS/GTS. During the period of excavation the pithorizontal displacement and forces of soil nail were observed. This article summers up thesoil nails internal force variation，finally design one optimization, there is also some guidingsignificance to practical engineering.Some soil nail parameters and soil parameters influencing the internal overall stability ofsoil-nailing wall: soil nail length、inclination、soil nail diameter and horizontal、vertical spacing、、 c and have been selected for analysising the stability by using the Lizhengsoftware for deep Foundation pit, and the effecting rules are concluded.