冲孔灌注桩钢筋笼对中施工技术的改进

Improvement on Reinforcing Cage of Filling Pile for Construction

冲孔灌注桩钢筋笼对中施工，一般采用外拔钢筋笼锚固筋，在主筋上绑扎混凝土垫块等施工技术，但对于空孔深度大、入岩深度大等复杂工况，则存在较大的局限性。在马南垌排洪河交通桥冲孔桩的施工实践中，进行技术改进，效果良好。改进要点包括：a、焊接钢筋撑架；b、采用空心锤扫孔；c、钢筋笼沉至孔底后上提50mm。

In constructing filling pile, the reinforcing cage was fixing up by exoscopic bolting steel bars and colligating with concrete bearing block. But due to deep hole and penetrating into rock, the ordinary method has its limit. The improvement was made in constructing the bridge on flood discharge ditch at Manantong by means of three measures, which were： 1 the support frame was pin up by jointing, 2 the hole was cleaned by rotary hammer, 3 the reinforcing cage should be lift up 50 mm when it get to bottom of the hole. It was shown by engineering practice that the effect of improved method is well enough.