Operating Principle Analysis Of Composite Structure With Scattered Piles And Soil Nailing

The scattered piles and soil nailing support is one type of composite soil nailing,mixing the supporting technologies of row piles、cables、soil nailing wall andcomposite soil nailing structure, forming the supporting system that the soil arch-rowpiles-soil nailing wall work together. There is no unified theory and design method forthe support bearing characteristics、the mechanics of the interaction between scatteredpiles and soil nailing、load transfer rules and the determination pf pile spacing, whichneeds further research.The paper studied inner force calculation of the composite support、soil archanalysis and design method by theoretical analysis and numerical simulation, basedon a project. The main contents are as follows:(1)The mechanics of soil arch、types and forms of scattered pile and soil nailingwere analyzed. Based on the hypothesis of parabola soil arch axes and plane activefailure surface between the scattered piles, the retaining characteristics of pile-soilnailing were analyzed, and three types o f slope failure were discussed, includingslope failure in front of soil arch, strength and slope failure of soil arch and slopefailure of the whole structure. T he formulas of the load ratio of soil nailing, the safetyfactors of shallow stability and base stability were derived.(2) Combining the calculation formula of inner force given before, the commondesign method of pile-soil nailing support was derived. According to the designcalculation of the foundation pit of Tianli center business square, the theory analysisdesign coincided with in-situ test results.(3)Simulating construction process of the pile-soil nailing by establishingthree-dimension finite difference model, and comparing with practical monitoringdata, the results accorded with the theoretical analysis.