Experimental study of defects in cast-in-situ bored piles and its application for superdeep defect treatment

After the finishing of piles, it was found that concrete defects at 63.0m-67.0m at the No.1 Bored pile in the North Channel Bridge of Hangzhou Bay Bridge B13 pier, which is at a diameter of 250cm with length of 96m. Aiming to successful treatment for this kind of defects, the present study proposed the pressurized concrete injection treatment techniques for superdeep defects in bored piles. In the paper, the experiment was carried out in comparing various mixed proportions of grouting, and the relationship analyzed between compressive strength and sound velocity for the treatment process. From these data an empirical equation between sound velocity and strength was determined, and the curve established. Following the superdeep pressurized injection of concrete treatment technique, the bored pile was successfully treated for the defects, ensuring the pile foundation achieving design criteria.