沪通长江大桥超长钻孔桩优质PHP泥浆施工技术研究

摘要

沪通铁路沪通长江大桥为公铁两用桥,其3号墩和4号墩为140m+336m+140m三跨连续刚性梁柔性拱专用航道桥中的两个主墩,钻孔灌注桩桩径2.50m,有效桩长115~120m,实际钻孔深度130~140m。针对桥址区长江厚砂层河床区钻孔施工易坍孔、成孔质量差的实际情况,对超长钻孔桩泥浆施工技术展开研究,对淡水PHP泥浆的性能、配方、拌制工艺和使用工艺等几方面进行重点论述。施工实践表明,沪通长江大桥超长钻孔桩淡水PHP泥浆性能优越,护壁效果好,胶体率高,可以显著提高钻孔效率,保证成孔质量,具有高回收率、环境污染少和良好的经济效应。%Hu-Tong Yangtze River Bridge on Hu-tong Railway is a combined highway and railway bridge. The P3 and P4 main piers of special channel bridge of three span (140 m+336 m+140 m) continuous rigid beam with flexible arch are a typical representative of super-long bored piles in the thick sand layer of the Yangtze River with 2. 50m designed pile diameter, 115~120 m effective length and 130~140 m drilling depth. In view of the fact that the thick sand layer may lead to borehole collapse and low quality pile drilling, a study is conducted on the construction technology of mud in super long bored piles of Hu-Tong Yangtze River Bridge, and the property, formula, mixing process and use of freshwater PHP ( partially hydrolyzed polyacrylamide ) mud are addressed. The construction practices show that the freshwater PHP mud has superior performance, good effect of breast wall and may greatly improve the drilling efficiency and ensure the hole-drilling quality. And it proves to be of high recovery rate, less environmental pollution and good economic effect.