Problems in underground construction: lessons learned and methods developed for success

Abstract

As with all engineering and construction developments, tunneling and underground construction projects require good design and thorough planning; they do not magically succeed or fail. Even when an underground construction project is well planned at its inception, conditions and requirements change during execution. The key to a project's ultimate success is the identification and management of risks during construction. For example, a contractor must acquire pertinent geological data, provide appropriate machinery, and deliver adequate materials and manpower for each facet of the work. Through a discussion of issues encountered and Lessons Learned on four major underground construction projects, this paper explores how owners and contractors can better identify and manage risk during construction, implement reasonable management actions, avoid time and cost impacts, and bring a project to a successful conclusion. It also explores how Lessons Learned on completed projects can serve as an invaluable springboard to better success in the construction of new underground projects. Underground construction projects discussed include the following: (1) Xiaolangdi Dam, China: One of the world's most complex intake structures, this project included the largest-in-diameter underground diversion tunnels and a massive plunge pool complex (water outflow and energy dissipating tanks); (2) Casecnan Multi-Purpose Project, Philippines: This combined irrigation and hydroelectric project involves the diversion and conveyance of water from two rivers through a 21-km tunnel to an underground powerhouse, where it is drawn from an existing reservoir and used for irrigation; (3) City Link, Melbourne, Victoria, Australia: This project included urban expressways, tunnels, elevated roadway, major river bridges, and a state-of-the-art electronic traffic and toll management system; (4) South Bay Wastewater Treatment Plant, San Diego, California, United States: This large sewage treatment plant entailed the construction of precast tunnel segments and drilling under the bottom of the Pacific Ocean. (A) Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.