Abstract:

A combining micropiles structure is a new retaining and reinforcement structure for slopes. This structure consists of several separated micropiles connected by a roof plate. The structure has the advantages of small pile diameter, easy and quick construction, operational safety and low cost. It can be applied to a moderate or small slope or landslide control projects. In particular, the structure is very suitable for dealing with project emergencies. According to the general load features of the structure, it is put forward that the part of the structure above the slip surface of a landslide may be regarded as a single rigid frame under landslide thrust. The part of each pile above slip surface can be analyzed by m-method in terms of elastic foundation-beam theory after the combined structure is equally deposed. The pressure on each pile by soil or rock mass among the piles above the slip surface are considered. Furthermore, the part of each pile below slip surface can be analyzed by k-method in terms of elastic foundation-beam theory. In this way, internal forces of the structure can be obtained after several iteration calculation. Analytical results show that each micropile in the structure is loaded by an axial force, a bending moment, and a shear force, but the axial force is principal. The new structure and its analytical method are successfully used in practice for a cutting slope in Guangyuan–Bazhong expressway project in China’s Sichuan Province. The performance of this structure is verified by experiments.

Key words: combining micropiles structure, landslide thrust, rigid frame, internal forces of a structure