Research On Internal Stability Analysis Of Soil Nailing Walls And Engineering Application Based On Combined Resistance

Since the70s of the last century, the interaction between the soil nail and soil is still a complicated issue among the research topics of soil mechanics. With respect to soil nails, researches mainly emphasized on the analysis and calculation of the axial force both in China and overseas; while only a little number of foreign scholars paid some attention to the improvement of resistance contributed by bending stiffness and shear strength. Regarding the shear and bending resistance of soil nails, it is generally recognized that the domestic society of civil engineering prevalently quoted the findings from abroad (ie. they merely take pull-out resistance into consideration), with only a limited number of literatures refering to the shear and bending force in China. In this thesis, the author prepared to make some theoretical study on the reinforcement of soil nails subjected to combined loading of pull-out, shear and bending force, and then propose a new mechanical analysis based on the revised limit equilibrium method, in order to contribute some beneficial attempt and supplement. The main contents of this thesis were listed as following:1. Concerned with the problem that the traditional design methods (e.g. China’s Building Foundation Support Specification JGJ120-99) only consider the role of the axial force in the reinforcement, omitting the bending and shear effects of soil nailing walls, the author revised the traditional design method, and proposed a new internal slope stability analysis method which was based on the limit equilibrium method.2. According to the international literatures, local mechanism of one soil nail under combined loading containing pull-out, shear and bending resistance in a slope was studied, and then the mechanical parameters were calculated with the help of MATLAB programming.3. Based on one foundation pit project in Ji’nan, the soil reinforcement improvement regarding bending stiffness and shear strength of soil nails was analyzed profoundly. Moreover, the force distributions, deformation characteristics of soil nails and the slope stability factors were studied. In conclusion, the current domestic design methods of soil nails are not economical, and it is necessary to revise them partially. The methodology proposed in this thesis can supplement some defects of the current domestic theories of soil nailing structures.