输电线路挤扩支盘桩受力特性的试验研究

Experimental Study of Squeezed Branch Pile Mechanical Characteristics in Transmission Line Engineering

挤扩支盘桩是一种具有较高的承载力和较小的沉降变形的新桩型。对某220kV送电线路工程的挤扩支盘灌注桩分别开展了下压+水平联合工况、上拔+水平联合工况和水平荷载的现场真型静载荷试验,得到了挤扩支盘桩在不同工况下的承载力、桩身轴力、桩周侧阻力和桩端阻力的分布规律。支盘桩的抗拔承载力较普通灌注桩提高约20%,支盘的存在使得桩身轴力呈现明显的阶跃式变化。根据挤扩支盘桩的荷载传递规律,建议承力盘间距不小于桩身设计直径的4倍,且不小于承力盘设计直径的2倍。

Squeezed branch pile is a new type of pile,which has higher carrying capacity and smaller settlement deformation.On-site static loading experiments of true squeezed branch piles taken from a220 KV transmission line engineering were carried out respectively,under different load conditions including compression plus horizontal combined loading,uplift plus horizontal combined loading and horizontal loading alone conditions.The bearing capacity,axial stress,and distribution of pile side friction and pile tip resistance of squeezed branch pile under different conditions were obtained.The uplift capacity of squeezed branch pile increases by about 20 percent relative to normal piles.The axial stress of squeezed branch pile presents obvious step jumping variation due to the branch plate.According to the load transfer mechanism of single squeezed branch pile,the space between loadbearing plates should be not less than 4dand 2D.