pilot tunnel

pilot tunnel

[′pī·lət ‚tən·əl]
(engineering)
A small tunnel or shaft excavated in advance of the main drivage in mining and tunnel building to gain information about the ground, create a free face, and thus simplify the blasting operations.
References in periodicals archive ?
construction of an approximately 1.5km pilot tunnel with minimum size of 5-metre internal diameter by tunnel boring machine connecting the vertical access shafts at Ho Man Tin and Ma Tau Kok;
To better understand the energy changes in deep tunnels during TBM tunneling, the current study took the headrace tunnel #1 at the Jinping II hydropower station when the TBM passed through the top pilot tunnel section as a case study.
Mr Tkacik, 43, from Slovakia, was working to enlarge the tunnel by removing rings of the existing pilot tunnel and spraying walls with liquid concrete, when a section of the roof collapsed, fatally crushing him.
Meanwhile, with the aim of understanding how the free face impact on the behavior of water infiltration, a pilot tunnel in the soil trough was excavated to simulate existential tunnel, which was supported by steel plates and wooden poles [42-44].
DIGGING of a pilot tunnel started on the Liverpool side the week before Christmas, 1925, followed on the Birkenhead side the following March.
Described by experts and engineers as a ''mission impossible,'' the completion of the long-anticipated Hsuehshan Tunnel, which consists of separate pathways for eastbound and westbound traffic and a pilot tunnel in the middle for emergency use, will reduce the time taken to shuttle between both places from three hours to less than 40 minutes.
Holmach have developed a pilot tunnel pasteuriser that is used for research work and trials on customer products.
The company started the construction of a pilot tunnel in Los Angeles last spring.
THERE was another hold-up in restoring normal working conditions of the pilot tunnel for the second Mersey crossing.
Seconds before this picture was taken, Wallasey and Liverpool were joined by a massive blast which blew away the remaining obstacle between them in the pilot tunnel under the middle of the Mersey, which would be opened as Kings way in 1974.
But in 1966 the pilot tunnel was cut and the construction of the main tunnel was underway in 1967.
Contract awarded for Sanbok Road Renaissance town planning modifications 4th year pilot tunnel retaining wall repair electrical works