德大铁路济南黄河桥超长钻孔桩成孔质量控制技术

德大铁路黄河特大桥100号、101号主墩位于黄河河道中间,基础采用钻孔桩,桩径2.0 m,最大钻孔深度达110 m,为解决由于钻孔过深易产生的桩身倾斜、钻进效率低、清孔难等问题,施工中选用了ZSD250型气举反循环回转钻机及刮刀钻头,并针对成孔垂直度、钻进参数、泥浆指标等关键因素采取一系列有效措施进行控制,成孔质量达到了理想效果,保证了成桩质量。

Quality Control Technology of Hole forming of Extra-long Bored Piles of Ji'nan Yellow River Bridge on Dezhou-Dajiawa Railway

The #100 and #101 main piers of the super major bridge on the Dezhou-Dajiawa Railway over the Yellow River are located in the middle of river channel of the Yellow River.Bored piles were used for the foundations,going down to 110 meters with the diameter of 2 meters.To solve the problems,such as pile body inclining,low drilling efficiency,difficult hole-cleaning and so on caused by extra-deep drilling operation,the ZSD250 gas lift reverse circulation rotary drilling rig and the drag bit were selected and adopted during construction.In addition,a series of effective measures were utilized to control the critical factors such as the perpendicularity of hole-forming,drilling parameters,mud indexes and so on.As a result,the ideal hole-forming quality has been achieved and ensured.