Norman Joyal’s CSM Method Paper Gains International Attention
Edited versions of Norman Joyal’s Cutter Soil Mixing (CSM) Method paper have recently been featured in Trenchless International Magazine and Trenchless Australasia Magazine. The paper, titled “Microtunnel Jacking and Receiving Shafts Constructed Using Cutter Soil Mixing (CSM) Technology,” was presented at the Australasian Society for Trenchless Technology (ASTT) Conference in 2009 and will be presented at the No Dig Conference in 2010. The paper refers to Contra Costa Water District’s Alternative Intake Project (AIP), which is the second known project in the U.S. to use the new CSM technology to build microtunneling shafts.
The CSM method excavates rectangular panels while simultaneously adding water to the soil to fluidize it in place to a prescribed depth. After excavation and retraction of the cutterhead, the cement grout is added and mixed with the fluidized soil to form a soil-cement mixture. To construct the shaft, the panels are interlocked to form a contiguous ring of panels. The CSM method is extremely useful in deep shaft installations under difficult ground conditions. By virtue of its guidance system (the inclinometer inside the cutterhead), there is greater assurance of the interlocking of the panels.
CSM was first introduced in Europe by BAUER Maschinen GmbH and also has been employed in Asia, and Canada. It was recently used in the U.S. to construct trench walls in Seattle and 36 foot (11 m) and 52 foot (15.8 m) deep shafts near Sacramento. It is currently being used to construct microtunnel shafts on the Balch Consolidation project in Portland, Oregon. Norm recently had the opportunity to give a presentation on CSM to Portland’s ASCE combined geotechnical and AEG group.
The AIP project involves the construction of a new pump station and approximately 13,200 feet (4,023 m) of 72-inch-diameter (182 cm) pipeline. The pump station is near its existing pumping facilities in the Sacramento Region Delta region east of the San Francisco Bay. Approximately 900 feet of the pipeline crosses under Old River, connecting to the District's existing Old River Pump Station Intake Facility. Construction of the river crossing requires installation of a 96-inch-diameter steel casing using microtunnel pipe-jacking techniques. The crossing also requires two watertight shafts: a 92-foot-deep jacking shaft and a 49-foot-deep (15 m) receiving shaft. The CSM method was used to construct the shafts. Because of the CSM method’s unproven track record, Norman provided full-time construction monitoring during shaft construction, excavation, and shotcreting, and during the microtunnel construction.
You can find a copy of the paper by visiting our Articles page.