Calculation method and application of internal force of anchor pile based on "three-stage method"

In view of the fact that the bottom surface of the loaded section and the top surface of the embedded section are not in the same horizontal plane due to geological conditions, topography and other reasons, this paper classifies this section as a secondary load section and derives the formula of designed load calculation and distribution about this secondary load section. As well as general formulas for the calculation of internal force, deflection of cantilever piles, anchor cable piles under elastic foundation beam and cantilever beam models. Taking the prestressed anchor piles of the reservoir bank protection project at Jiaojiawan resettlement site in Badong County as an example, the influence of the internal force and deflection of the anti-slide piles in the secondary load section is studied. The results show that the traditional calculation method that ignoring the effect of the earth pressure after the secondary load will make the calculation result of the pile bending moment smaller and leads to insufficient reinforcement of the pile, which really has a safety risk. Taking the number and position of the anchor cables as the control variables, the influence on the internal force and deflection of the prestressed anchor cables is studied, and it is proposed that the prestressed anchor cables can effectively reduce the construction cost of anti-slide piles; increasing the number of prestressed anchor cables which is beneficial to adjust the internal force distribution of anti-slide piles, and multi-row anchor cables should be given priority in the design.