微型桩杆塔基础上拔试验研究

摘要

Field tests were done to study the uplift bearing mechanism and the uplift design method of micropiles. Study shows that the uplift bearing capacity of single pile is composed of pile weight and lateral friction; the second grouting can increase the uplift bearing capacity of micropiles, calculating the uplift bearing capacity of two-grouting micropiles must consider the effect of the second grouting; the obliquity of inclined piles in the micropile group can be 10°; under uplift load, the bearing load of the angle pile is maximum, the side pile is the second, and the middle pile is minimum; in this experimental condition, the uplift pile group effect coefficient is 0. 7.%通过现场真型试验,对微型桩基础抗拔承载机理及其抗拔承载力计算方法进行了研究.试验研究表明:微型桩单桩抗拔承载力可由桩身自重和桩周侧摩阻力相加组成；二次注浆有利于提升微型桩抗拔承载力,在进行微型桩抗拔承载力计算时应考虑二次注浆的提升作用；群桩基础中布置斜桩可采用10度倾角；由于承台对上拔荷载的重分配,在上拔荷载作用下,角桩承力最大,边桩次之,中桩最小；本次试验条件下,微型桩抗拔群桩效应系数可取0.7进行计算.