Quality evaluation of pile integrity by bidirectional dry jet mixing method based on low-strain integrity tests

The low-strain reflection wave method for the pile foundation is an inspection technology. It has advantages such as rapid detection speed, intuitive reaction, strong adaptability. At present this method has been widely used in pile foundation (cast-in-situ bored piles and prestressed pipe piles). Nevertheless problems still exist in terms of monitoring of pile shaft completeness and pile length for DJM piles. In this study, the applicability and specific standards of inspection methods for bidirectional DJM piles are discussed. The low-strain dynamic test method is proposed to detect the strength the pile length and characteristics of bidirectional DJM pile body. Through the in-situ core tests, this method is verified in term of bi-directional DJM pile tests, and applied in Lianyungang-Linyi highway (Jiangsu province) LL-8 section bidirectional DJM pile project, and convinced results are achieved.