Abstract:

In order to explore the application of micro-row-pile in supporting structure of open-cut tunnel with high-steep slope, the design and calculation method for three-row-pile supporting structure is proposed based on two-dimensional load structure model. The internal force and deformation characteristics of the row-pile supporting structure, the adaptability of different schemes, and the influence of steel pipe pile diameter are studied based on various supporting schemes, combining with engineering cases. Results show that: (1) The characteristics of internal force and deformation of the front row pile is almost the same with that of the middle and the rear row piles, but the largest value is slightly larger. (2) It can effectively reduce the displacement and internal force of supporting structure by adding anchor cable or retaining rock at the bottom of the pit, which can reduce the vertical distance between adjacent supports. (3) With the increase of pile diameter, the horizontal displacement of supporting structure decreases exponentially with the stiffness of steel pipe pile. (4)Only increase the diameter of the front row of pile can also effectively reduce the deformation of the supporting structure. When designing support structures, suitable supporting mode, and steel pipe pile diameter can be selected according to the excavation height, construction machinery, terrain characteristics, etc., so as to achieve rapid and mechanized construction.

Key words: tunnel portal, open-cut tunnel, micro-row-pile, steel pipe pile, supporting structure