Page 472 - Trenchless Technology Piping Installation and Inspection

422 App endix D

Ground mat: Usually used in horizontal directional drilling, metal mats
rolled out on either side of drill rack for operators and crew to stand on
during operation to give grounding protection in case of electrical
strike.
Ground rod: This is a copper or brass rod that is hand driven into the
ground and is connected to the drill rack and mats to provide adequate
grounding of an HDD rig.
Groundwater table (or level): Upper surface of the zone of saturation in
permeable rock or soil (when the upper surface is confined by impermeable
rock, the water table is absent).
Grout: (1) Material used to seal pipeline and manhole cracks; also used
to seal connections within pipe or sewer structures. (2) A material, usually
cement or polymer based, used to fill the annulus between the existing
pipe and the lining; and also to fill voids outside the existing pipeline.
(3) A material such as cement slurry, sand, or pea gravel that is pumped
into voids.
Grouting: (1) Filling of the annular space between the existing, old, or
host pipe and the carrier pipe. Grouting is also used to fill the space
around laterals and between the new pipe and manholes. Other uses of
grouting are for localized repairs of defective pipes and ground
improvement prior to excavation during new installations. (2) The
process of filling voids, or modifying or improving ground conditions.
Grouting materials may be cementitious, chemical, or other mixtures. In
trenchless technology, grouting may be used for filling voids around the
pipe or shaft, or for improving ground conditions. (3) A method of filling
voids with cementitous or polymer grout.
GRP: Glass reinforced plastic, a family of renewal linings. Often
generically known as reinforced plastic mortar (RPM) and reinforced
thermosetting resin (RTR).
Guidance system: The guidance system continuously confirms the
position of the TBM.
Guide rail: Device used to support or guide, first the shield and then the
pipe within the drive shaft during a pipe jacking or utility tunneling
operation.
Guided auger boring: Pilot tube microtunneling. A modified version of
horizontal auger boring method.

Guided boring: This term is used in Europe for small diameter horizontal
directional drilling method.
Guided drilling: See guided boring.
Gunite: A renewal technique that employs steel reinforcement fixed to
the inside surface of an existing sewer line, which is sprayed with dry
concrete.