Erez N. Allouche, John C. Matthews, Sebastian Gauthier and Kevin Nagle
Papers # 2010 Vancouver
While pipe bursting is a well accepted in-line replacement method for gravity sewers and drains in North America, it presents several limitations. The size of the equipment needed to burst pipes 200 mm or greater in diameter is too large to fit inside a typical 1.2 m diameter manhole. Also¸ the force needed to fragment the host pipe, displace the soil and push the fragments into the soil is substantial.
A reaction wall is typically needed to counteract this force. In cases where the manhole wall has been used for this purpose, damage has been sustained necessitating extensive rebuilding of the manhole structure. This could be particularly costly in hilly areas characterized by deep, gravity driven collection systems. The Tight-In-Pipe (TIP) method¸ which features a close-fit, pull-in, thermoplastic slipliner was developed to avoid the time and cost associated with construction related damages, accelerate construction time and minimize equipment requirements. The method has been utilized in Germany for several years now with considerable success. The Trenchless Technology Center (TTC) was commissioned to assist IPEX Inc. in testing a new segmental, flash joint PVC pipe compatible with the TIP method. The work was performed in two phases. Phase I of the work included an extensive survey of common ranges of internal diameters for gravity drain and sewer pipes between 4" and 12" for typical pipe materials.
A secondary objective was to gain an insight into typical manhole-to-manhole distances as well as the distribution of the internal diameter of manholes in North American cities. Phase I of the work also included performing laboratory tests utilizing a 6' x 4' x 12' long soil structure interaction chamber aimed at quantifying the axial force needed to overcome the hoop strength of typical non-reinforced gravity sewer and drain pipes buried at different depths in granular soil conditions. Phase II of the project¸ which consisted of a fullscale field test using a modified TIP method¸ where the host pipe is burst just enough to create the minimum void needed for pulling-in the replacement pipe. Pulling load and in-situ soil pressures were monitored during the installation.
Following the installation the newly installed pipe was subjected to a pressure test as well as a CCTV inspection. The paper provides a summary of the above described research and testing program, with focus on Phase 2 of the project, the full scale field installation. The results of the study suggest that TIP is an effective method for the rehabilitation of gravity driven sewer pipes in locations where any excavations are undesirable. TIP provides another tool to municipal engineers as seek to maximize the footage of pipe that can be rehabilitated with limited budgets. .