Tunnel excavation for the LCLS has officially begun behind the Collider Hall. After weeks of preparing a concrete portal through which to begin digging, crews fired up a machine called a "roadheader," which uses a rotating head spiked with Jurassic-looking teeth to chew through the soft sandstone. Excavation crews will spend the next nine months at work in the tunnel, eventually excavating the underground Far Experimental Hall and connecting to the Near Experimental Hall (NEH) currently under construction.
Survey crews use a system of lasers to guide the roadheader along its underground path. A special low-profile excavator follows behind the roadheader to collect and remove the spoils. Crews stop digging every four feet to erect a steel brace and spray liquid concrete to shore up the inside of the tunnel.
Also underway this week, concrete trucks have returned to pour the walls of the NEH. Within the next couple of weeks, a second roadheader will be put to work in the Research Yard to excavate the Undulator Hall and connect it to the NEH.
In picture:
1.The roadheader's many "teeth"
2.Side view of the roadheader
3.The roadheader begins its work behind the Collider Hall
4.The tunnel begins to take shape behind the Collider Hall
Contact:
Stanford Linear Accelerator Center, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy
