Microtunneling through Abrasive Soil with Cobbles and Boulders: Construction of the Santa Ana River Interceptor (SARI) Relocation

摘要

The Santa Ana River Interceptor (SARI) Relocation Project in Yorba Linda, CA will relocate fourmiles of existing interceptor sewer pipeline out of the Santa Ana River scour zone. Approximately 4,700 feet of theproduct pipe will be installed by 77 to 101.5-inch diameter microtunneling in 5 segments, including 2 siphoncrossings and 2 curved tunnels, one of which is a 1,567-foot S-shaped alignment. Tunneling was chosen to avoidconstruction impacts to the community and environmental impacts along the river. One of the tunnels may cross theWhittier-Elsinore Fault Zone.Soil conditions on the project include a complex mix of alluvium with abundant cobbles and boulders in a weaksandy matrix. During design, subsurface investigation reports indicated abrasive soils based on Miller testing.Groundwater levels are well above the pipeline elevation during flood season along several of the tunnels.Temporary shaft structures are excavated up to 70 feet deep and include the use of cement deep-soil mixing, secantpiles, and soldier pile and lagging walls with permeation grouting designed to limit groundwater inflow.This paper describes how the microtunnel machine was selected based on the anticipated geotechnical conditionsand how it performed in this environment. The machine design included the capability of compressed air faceaccess. The relation between soil abrasivity laboratory testing and equipment wear and tool life is presented.Information related to planning and constructing curved drives is offered.