The design, installation and performance of an uncommon anchorage system, namely the jack-in pipes, are presented in this paper. This anchorage system has been used as the support system for a temporary excavation of 9m deep basement in loose sandy alluvium deposits overlying Kuala Lumpur limestone. Jackin pipe system has advantages of rapid installation, practically no grout curing time prior to anchorage stressing and easy removal after used. However, there are also some disadvantages of this anchorage system, such as short penetration length due to limitation of reaction system, poor penetrability in stiff soils and obstructions, limited pipe inclination, complication of wall performance affected by reaction system and difficulties in backfilling the voids after removal of pipes. This paper discusses the design concept, problems associated with the installation methods, construction control and performance of this anchorage system. The design theory with consideration of the change in radial stress of pipe due to pipe insertion, the ultimate skin resistance at the pipe/soil interface and the role of bending stiffness of pipe are discussed. Results of six numbers of pull-out tests carried out on this anchorage system are presented. In these tests, the jack-in pipes at different depths of overburden soil are pulled to failure and the test results show a satisfactory performance of this anchorage system.
This paper summarises the pull-out test results of an unusual anchorage system using hollow steel pipes jacked into the retained ground as both the anchorage and the reinforcing elements. This innovative anchorage system was firstly intended to retain a basement construction with maximum excavation depth of 9m in sandy alluvium subsoil. In this case history, the conforming design for the wall anchorage system was the conventional ground anchorage with fixed length in limestone bedrock.