Test And Calculation For Bearing Capacity Of Manual Digging Pedestal Pile

As the high-rise buildings and large bridges continue to emerge, pile foundation is greatly used in the engineering design. Especially manual digging pedestal pile, with its simple construction, reliable quality, bearing properties, no noise pollution, etc. have been widely used.Because of the diversity of the actual construction of the pile, the regional geological conditions, coupled with the static load test cost, long duration, it is not very realistic to completely determine single bearing capacity of each pile and each project by static load test. If there exists a method that take advantage of soil around the pile and its geometry, physical properties and set up a finite element model, it is possible to calculate and determine the bearing capacity of pile and mechanical behavior, to quantify the stress state and the ultimate bearing capacity in the static load test, which can not only save a lot of on-site testing costs, but also study a variety of related issues by the model, so it can play a guiding role in the design and construction.According to the construction records and geological data of an engineering manual digging pedestal pile, establish the finite element model of pile soil system, exert the boundary conditions according to the spatial layout of the pile and select the appropriate conditions for the convergence in order to calculate by the finite element method. At the same level of load, the results of finite element analysis are same as that of static load test in the top displacement, pile stresses and pile-side stress, indicating that using ANSYS finite element software in pile-soil interaction simulation system is feasible. When the project is not available for static load test due to various practical problems or the number of static load test is insufficient, the finite element results can be used as design reference.Making use of the background to the project and the finite element model, carry out the word that calculate the bearing capacity of digging holes reamed pile end calculations and expand the diameter of manual digging pedestal pile, optimize the pile aspect ratio and the expansion of the bottom of the pile and then discuss the effect of aspect ratio and diameter to the bearing performance. Analysis shows that: when the pile aspect ratio range is 25 to 30, the side resistance and tip resistance of the pile plays more reasonable. When the aspect ratio is larger, the role of the expansion of the bottom cannot be fully exerted. Expansion of the bottom changes the transmission path of the shaft resistance in order that a greater degree of stress of the soil spreads down to the edges, so that the mechanical properties of pile play more reasonable. Belled diameter is not the bigger the better. When D/d is more than 2.6, the pedestal area and bearing capacity increase has been disproportionate and the economy of design has been reduced.