Microtunnel Jacking and Receiving Shafts Constructed Using Cutter Soil Mixing (CSM) Technology
Abstract
The cutter-soil-mixing (CSM) method, a construction technology relatively new to the United States, is being used on a Contra Costa Water District project in northern California to construct 50- and 90-ft (15- and 27-m) deep watertight shafts in difficult ground conditions. The shafts will be used for a 900-ft (275-m) long microtunnel crossing of Old River. This is the second known application of this technology in the U.S. for the construction of microtunnel shafts and the first known application using shotcrete-reinforced walls. The shafts penetrate soft saturated silts and clays and loose-to-dense sands. Existing construction techniques, such as secant piles and slurry walls, were not considered feasible for the deeper shaft due to pile drift during installation, which can result in “windows” between the panels/panels. Caissons constructed in the wet were considered the most feasible method for the ground conditions. Rather than specifying a design, however, a performance-based specification was prepared, allowing contractors to provide their own designs. The successful contractor, proposed the use of CSM. CSM was first introduced in Europe by BAUER Maschinen GmbH and has been used in Europe, Asia, and Canada. It was recently used in the U.S. to construct trench walls in Seattle, Washington, and 36- and 52-ft deep (11- and 16-mdeep) shafts near Sacramento, California. This paper will focus on the shaft design, equipment features, construction, quality control, and constructed shafts for the Contra Costa project.
2010
Australasian Society for Trenchless Technology Conference Proceedings
Norman Joyal
Jacobs Associates
