conventional tunneling full report
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CONVENTIONAL TUNNELLING.pptx (Size: 307.36 KB / Downloads: 209)
Namrata M. Lolge (09CM16F)
M. Tech. 1st sem
A definition of Conventional Tunnelling can be the construction of underground openings of any shape with a cyclic construction process of-
1. excavation, by using the drill and blast methods or mechanical excavators (except any full face TBM)
3. placement of the primary support elements such as-
-steel ribs or lattice girders
-soil or rock bolts
-sprayed or cast in situ concrete,
Principles of conventional tunnelling
Conventional Tunnelling is carried out in a cyclic execution process of repeated steps of excavation followed by the application of relevant primary support, both of which depend on existing ground conditions and ground behaviour. An experienced team of tunnel workers (miners), assisted by standard and/or special plant and equipment shall execute each individual cycle of tunnel construction.
The Conventional Tunnelling Method mainly using standard equipment and allowing access to the tunnel excavation face at almost any time is very flexible in situations or areas that require a change in the structural analysis or in the design and as a result of this, also require changes in the support measures.
The processes involved in the cyclic operation of conventional tunnelling are
6. Loading/Muck removel
CYCLE OF OPERATION IN TUNNELLING
SET OF EQUIPMENTS
A standard set of equipment for execution of conventional tunnelling may consist of following items
Drilling jumbo to drill holes for blasting, rock bolting, water and pressure release, grouting etc.
Road header or excavator in cases where blasting is not possible or not economic
Lifting platform allowing the miners to reach each part of the tunnel crown and of the tunnel face.
Lifting equipment for steels sets
Loader or excavator for loading excavated ground into dump trucks.
Dump trucks for hauling excavated ground.
Set of shotcrete manipulators for application of wet or dry shotcrete.
Conventional tunnelling enables :
A greater variability of the shapes.
Better knowledge of the ground by systematic exploratory drilling at the tunnel level ahead of the face.
Greater variability in the choice of excavation methods according to the ground conditions.
Easier optimisation of the primary support using observational method in special cases.
A greater variability in the choice of auxilliary construction methods according to the ground conditions
Conventional tunnelling is specially convenient for:
Difficult ground with highly variable ground conditions.
Projects with highly variable shapes of cross sections.
Projects with a higher risk of water inflow under pressure.
Projects with difficult access.
The conventional method for tunnelling entails the use of
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