复杂地质情况下深水大直径钻孔桩快速施工技术

Rapid Construction Technique for Large Diameter Bored Pile in Deep Water Area and under Complex Geological Condition

黄冈公铁两用长江大桥为双塔双索面钢桁梁斜拉桥,其2号桥塔墩钻孔桩施工采用冲击钻开孔、钢护筒及时跟进、气举反循环钻机成孔的组合方式成孔,实现了倾斜裸岩面、岩层软硬不均、基岩裂隙发育等复杂地质情况下钻孔桩日平均成孔2m的速度;采用钢筋笼"长线法"制作、整体吊装,导管预拼装、整体吊装,储料斗方法灌注混凝土的成桩工艺,使直径3.0m、桩长42.5m的深水钻孔桩施工平均4d成桩1根。实桥施工效果表明该钻孔桩采取的一系列快速施工方法快捷、有效。

The Huanggang Changjiang River Rail-cum-Road Bridge is a two-pylon steel truss girder cable-stayed bridge with double cable planes. During the construction of the bored pile of the No. 2 main pylon, the method of using impact drill in hole drilling, steel case in supporting and air-lift reverse circulation in hole forming was adopted, realizing an average speed of drilling drill 2 m downward a day under the complex geological conditions of oblique rock surface, softhard rock staggering layer and bedrock fissure development. The pile construction technique of steel case fabrication by long line method, steel case monolithic lifting and installing, pre-assembling and monolithic lifting and installing of conduits as well as using storage hopper to pour concrete ensured that the formation of a deep water bored pile of 3.0 m in diameter and 42.5 m in length would be completed within an average of 4 days. The construction effect of an actual bridge indicates that the rapid construction technique for bored pile construction is time-saving and efficient.