高速铁路跨黄河大桥超百米级钻孔灌注桩成孔技术

Hole Forming Technology of Cast-in-situ Bored Piles for Extra-100-meter Drilling in the Yellow River of High-speed Railway Bridge

为实现黄河深厚覆盖层上的高速铁路桥梁水中超百米级桩基高质量成孔,结合工程经验,设计钢管桩、贝雷梁形成钢栈桥钻孔作业平台,采用履带反循环和气举反循环钻机联合钻进。钢护筒长度适当加深,入土深度14~21 m。钢护筒底部壁厚加大至22 mm或者底部包边处理。钢护筒采用导向架埋设。钻孔深度在30 m以内,护壁泥浆密度、黏度、含砂率随着钻孔深度增加而逐渐增加;钻孔深度超过50 m,护壁泥浆密度、黏度、含砂率基本不变。塌孔轻微时,填水泥、膨润土、锯末,增大泥浆相对密度,增强泥浆护壁,控制钻进速度。通过上下抖动钻头,必要时提钻至地表,人工处理糊钻。采用超声波法检测仪对超百米级钻孔成孔质量进行检测,成孔质量优良。

To realize the high-quality drilling of a high-speed railway bridge pile foundation with more than 100 meters in water on the deep overburden layer of the Yellow River,combined with engineering experience,the steel pipe pile and Bailey beam are designed to form a steel trestle drilling operation platform,and the combined drilling of crawler reverse circulation and air lift reverse circulation drilling rigs is adopted.The length of the steel casing is appropriately deepened,and the embedded depth is 14~21 m.The bottom wall thickness of the steel casing is increased to 22 mm,or the bottom is hemmed.The steel casing is buried by the guide frame.When the drilling depth is within 30 m,the density,viscosity,and sand content of the wall-protecting slurry gradually increase with the increase in the drilling depth.When the drilling depth is more than 50 m,the density,viscosity,and sand content of the wallprotecting slurry are basically unchanged.When the hole collapse is slight,cement,bentonite,and sawdust are filled to increase the relative density of slurry,enhance the slurry wall protection,and control the drilling speed.Paste drillings can be manually treated by shaking the drill bit up and down and lifting the drill to the surface,if necessary.The ultrasonic detector is used to detect the quality of the ultrahundred-meter drilling hole,and the quality of the hole is found to be excellent.