Application Study Of Pile Foundation Underpinning Technology In Subway Construction

Underpinning technology is a special construction method; it is difficult, costly, a long project time and more responsibilities. This construction method had been developed quickly when many subway tunnels were built in New York City, since 1920-30s. The comprehensive underpinning technology is adopted when built subway tunnel in German in 1960-70s. The domestic adoption of this method was started after 1970s, when reinforced, maintained old buildings. In 1995, this special method was adopted in Guangzhou subway construction line 1.There will be more problems to disposal the pile foundation of tall buildings with rapidly developments in city subway construction. This paper is based on engineering practice in Guangzhou subway line 3, and gives depictions about underpinning technology from its formation, development and innovations, and summarizes its basal construction techniques, methods, applications, experiences and characteristics. Some key technical matters in pile foundation underpinning have been solved with analytical study, optimized design. This paper can be used as a new idea in other similar construction.