输电线路掏挖基础机械成孔过程中孔壁土体稳定性分析

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

针对输电线路掏挖基础成孔过程中孔壁稳定性的问题,以机械化旋挖钻机成孔的掏挖基础孔壁土体为研究对象,采用FLAC3D数值模拟软件,对旋挖钻机成孔过程中孔壁土体的变形破坏过程进行模拟分析,研究了开挖过程中掏挖基础孔壁土体的稳定性及影响因素.研究结果表明,钻机的自重荷载与开挖卸荷作用对孔口处和扩大头处土体的水平向位移影响较为明显;不同埋深基础的孔壁土体塑性区的分布面积和延伸范围均存在差异,随着埋深的增加,基础扩大头处的塑性区面积和延伸范围也随之增大,因此,现场机械化开挖施工过程中应重点关注孔口和扩大头附近部位的变形破坏.该研究成果可为机械化旋挖钻机成孔技术在我国输电线路工程杆塔掏挖基础施工的应用提供理论依据.

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 FLAD3 D was adapted to analyzing the distribution lawof soil displacement,plastic zone and the stability of borehole wall during drilling. The calculation results showthat 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.