Geotechnical Site Investigations for Underground Projects Volume 1 (1984) / Chapter Skim
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Glossary
Glossary
Pages 169-182
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From page 169... ...
in tunnel ing, drifting, or in raising or sinking a shaft. ARCH The configuration of the upper portion of a tunnel section above the springline; the crown, roof, or back of a tunnel.
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From page 170... ...
BLOCKING Blocks of wood or concrete installed between the lagging or steel sets and the rock surfaces of a tunnel to transfer stress to the sup ports. BLOCKY ROCK Rock having joints or cleavage spaced and oriented in a manner such that it readily breaks into loose blocks under excavation conditions.
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From page 171... ...
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From page 172... ...
CRaiN The highest point of an arched tunnel cross section; the roof or back of a tunnel. CRONB BARS Timbers or steel members cantilevered from previously installed sets nearest the heading to temporarily support a rock tunnel roof while the next set is being installed.
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From page 173... ...
PINAL LINING Long-term shaft or tunnel support installed for permanent stability or other user requirement, often incorporating the initial support elements1 also referred to as •permanent lining,• •permanent support,• •final support.• PIIII GROUND Consolidated sediments or soft sedimentary rock in which the tunnel heading can be advanced without any (or with only minimal) roof sup port, and the permanent lining can be constructed before the ground begins to move or ravel.
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From page 174... ...
GRIPPER TBM A rock tunnel boring machine which generally utilizes roller disc cutters as excavation tools and which moves forward by reacting (i.e., exerting shove forces) against the tunnel walls through a hy draulic gripper reaction system.
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From page 175... ...
BARD ROCK In construction, rock having a strongly bonded nature such as to re quire excavation by blasting or the use of specially hardened cuttersr generally includes igneous and metamorphic rock and the more strongly bonded sedimentary rocks.
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From page 176... ...
LAGGING Wood planking or other structural materials spanning the area between ribs. LIHER PLATE Iron or steel plates which can be fastened together to support the arch, sides, and in some cases the invert of a tunnel.
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From page 177... ...
'l'he removal operation is termed •mucking• or •mucking out.• MULTIPLE-DRIPT EXCAVATION A tunneling method in which two or more parallel drifts are pre-exca vated in orde.r to install partial ground support before the full tun nel cross section is opened up between them. OPBN-ctJT TUNNEL A tunnel constructed by excavating a trench from the surface, build ing the structure within the trench, and then backfilling to restore the surface.
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From page 178... ...
RAISE BORE AND SLASH To raise bore a shaft of moderate size, then enlarge to a greater di ameter by means of blasting, or •slashing.• RAVELLING GROUND Poorly consolidated or cemented materials that can stand up for sev eral minutes to several hours at a fresh cut, but then start to slough, slake, or scale off. RIB A part of the tunnel support, usually of structural steel, curved to suit the shape of the tunnel section.
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From page 179... ...
ROCK BOLT A round steel bar, sometimes very long but usually less than 25 ft long, equipped with an expandable anchor at the far end, inserted in drilled holes around the periphery of a tunnel to tie rock-blocks or strata together and prevent their loosening or falling out. It may be locked into the hole mechanically or with some type of grout.
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From page 180... ...
See also soft-ground shield and gripper shield. SBO'l'CRB'l'B A form of quick-setting concrete with aggregate generally no larger than 3/4 in., sprayed on freshly excavated rock by air pressure to provide early, flexible support and sometimes applied more thickly to provide permanent support.
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From page 181... ...
Sometimes referred to by construction people as •slicks.• SLURRY SBIBLD A closed-face shield designed for tunneling in very soft, wet, or running ground by use of circulating, pressurized clay slurry against the face to counterbalance earth pressures, prevent ingress of water, and also to carry away the cuttings. SIIOOTII BLAS"l"IHG A technique of using carefully controlled shot hole drilling and spe cially prepared charges in peripheral blast holes to reduce overbreak.
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From page 182... ...
Distinguished from heading-and-bench construction. '.l'UNNEL An elongate, essentially linear excavated underground opening, gen erally with a length greatly exceeding ita width or height.
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Key Terms
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