Abstract: Adopting the step loading method on combined structure of spatial truss micro-pile system as supporting structure , the changing law of internal force of micro-pile system is studied by new geological mechanics model test. According to the test methods and the state of force of the space truss micro-pile system, the structural analysis solution which is under the conditions of step cyclic loading and based on the elastic foundation beam constrained laterally is deduced. The test results show that, under the conditions of the broken-rock soil, the link beam can effectively limit the micro displacement of pile top; and the moment of pile body reduced; the soil pressure distribution in front of the pile is relatively uniform in sliding body; the distribution of the moment of each row of micro-piles is relatively close to each other; the maximum moment is close to the sliding face. The structural analysis solution based on the elastic foundation beam constrained laterally deformation can describe the changing law of internal force and distribution rule of micro-pile system after step cyclic loading better. The research results have a good reference value for correct analysis of anti-sliding mechanism and anti-sliding design of the micro-pile.

Key words: micro-pile combined structure, model test, anti-sliding mechanism