The Numerical Analysis Of Small Rigidity Stiff Cement-soil Retaining Wall Foundation Pits Supporting

The small rigidity stiff cement-soil retaining wall bracing structure is a new method of foundation pit bracing, which is constructed after finishing the cement soil mixing pile and before the cement-soil initial setting by inserting the small rigidity material in the area inward and outward the cement-soil retaining wall where tension and compression stress are larger. This method has many advantages such as reliable safety, economic cost, convenient for construction and little influence on environment.By means of combining with engineering instances and indoor experimental results, the paper created 3D finite element model and analyzed the displacement and stress fields of soil and bracing structures, and the distributed law of the cement interface stress during the whole excavation process of the foundation pit with the finite element program ANASYS. Making use of the finite element method, the paper analyses the influence of different excavation depths (engineering status), different types of the section steel, different disposition forms, different cement-soil materials, different thickness of the retaining wall and different embedded depths of the section steel to the displacement and stress of the retaining wall, and gained the displacement and stress curves of the retaining wall, the stress curve of the section steel, the relative slippage curve between the section steel and cement-soil, and the distributed curve of the side friction. Via these curves and so on, the dissertation analyses the distributed law of loads and deformation characteristics thoroughly, and got a few useful results: the influence caused by the change of the section steel type (in the range of the small section steel: No.14- No.20) to the resistance deformation ability was insignificant; according to different disposition forms of the section steel, the horizontal displacement of the bracing structure decreased obviously with an increase in quantities of the section steel, when steel insert in every two piles the maximum horizontal displacement of double row steel is less than single row steel by 34.8%; in the same time double row steel is less than single row steel by 24.7% when steel densely disposal in piles; using the single row steel the densely disposal steel is less than the every two piles method by 50.6%; using the double row steel the densely disposal steel is less than the every two piles method by 42.9%. the interaction between the section steel in the sandy cement soil pile and cement soil was larger than the clay pile, and that with an increase in the adulterated ratio of cement, the load shared by the cement soil pile increased continuously; when the cement soil piles changed from three rows to four rows, the horizontal deformation of piles and the stress of section steels changed diminutively. Besides, the dissertation simulated different embedded depths of the section steel, and the result was that the deformation of the bracing structure decreased with an increase in the embedded depth. By means of comparing with engineering instances, it validated that the finite element model in the paper has a good...