Model Test And Calculation Method Research On Portal Double-row Anti-slide Piles

Portal double-row anti-slide pile, as a class of double-braced structure, differs from the cantilever piles, retaining walls and other supporting structures. Its front and rear piles are connected by the tie beam and other connecting members, which forms a space system, enhances bending, shear capacity of the structure and helps to improve skid resistance of anti-slide pile. Thus, portal double-row anti-slide piles are more and more widely used in slope treatment engineering. Pile-soil interaction mechanism is the core issue of scholars at home and abroad, but there is not yet any consensus on it. The calculation models and methods proposed by different scholars have a greater difference, which makes it difficult to carry out the reasonable design of the portal double-row anti-slide pile.The paper, based on indoor model test, used model tests, numerical simulation and theoretical analysis to study portal double row anti-slide pile design influencing parameters, the interaction between piles and soil and piles sustained force conditions, which can provide the basis for anti-slide design calculations.The main contents include:(1) Through the design of portal double row anti-slide pile model test, under different experimental conditions, the displacement of the Top of the pile, the corner of the pile and the change of the soil pressure front and behind pile are analyzed. The impact of different anchorage depth and having tie beam on the top of pile or not on skid resistance of anti-slide pile and soil pressure distribution rule are gotten.(2) The pile-soil interaction model is established by the finite element software ANSYS. The size and distribution of stress and strain in pile-soil, bending moment and shear are analyzed. The impact of different pile spacing, pile-sectional dimensions, tie beam sectional dimension and anchorage depth on skid resistance of anti-slide pile are compared, and the reasonable range of this four kinds design parameters are proposed.(3) The soil between the piles is considered to be the elastic-plastic in this model which combined the linear elastic model and the plastic model. A calculation method for calculating internal force of the fore-pile and the rear-pile is developed, which is based on structural mechanics, soil constitutive relationship and numerical method. Then, combining with engineering example, the internal force of portal double-row anti-slide piles is calculated with the finite element program ANSYS. Compared with the monitoring data and the calculating results of elastic model, the calculating results of elastic-plastic model are consistent with the monitoring value.(4) The elastic-plastic calculation method about anchoring segment displacement and internal forces in rigid and elastic pile is proposed. By comparison with the elastic calculation methods and experimental values, the feasibility of the method is verified.(5) Based on Structural mechanics displacement method, the tie beam section size calculation formula of portal double row anti-slide pile is proposed. And through ANSYS software analysis to compare engineering examples, the result shows that the structures of the finite element calculation results are consistent with theoretical calculations. The feasibility of the formula is verified.