Development and assessment of equivalent rock strength parameters for the back-analysis of pipe-jacking forces

During the Kuching Wastewater Management System Phase 1 project for Kuching City, micro-tunnelling via the pipe-jacking method was used to construct 7.7 km and 5.4 km of trunk and secondary sewer lines respectively. The constructed pipelines traversed highly fractured rock, at depths between 10 m and 35 m below the busy CBD of Kuching City. Through research and industrial collaboration with sponsors Hock Seng Lee Bhd, and Jurutera Jasa (Sarawak) Sdn Bhd, a novel testing method using reconstituted tunnelling rock spoils was developed to assess the jacking forces in the absence of intact rock cores for strength testing. This novel testing method has been validated through back-analysis of field measurements, and 3D finite element analysis. The research outcomes have been applied successfully to validate at least eight pipe-jacking drives traversing various geological formations in Kuching City. The work in this thesis has been presented at various international conferences, and has also been published in the highly-respected Journal of Geotechnical and Geoenvironmental Engineering by the American Society of Civil Engineers.