Stability analysis of borehole wall of digged foundation of transmission line during mechanized drilling

In order to investigate the stability of soils around the hole wall in digged foundation, this paper took the soils around the digged foundation by mechanized drilling as the research object, the finite-difference 3-D program FLAD3D was adapted to analyzing the distribution law of soil displacement, plastic zone and the stability of borehole wall during drilling. The calculation results show that the drilling rig weight and excavation unloading had the obvious effect on the soils horizontal displacement around orifice and enlarged base, and the soils plastic zone distribution after excavation also appeared the significant differences in two aspects: one was the plastic zone distribution area and the other was the plastic zone development range. Thus, soils deformation around orifice and enlarged base should be paid attention extensively in site construction process. This study provides theoretical basis for tower foundation designing and construction during transmission line mechanized construction.