For support approach it involves the application of reaction force at the face of excavation by using heavy structures, primarily ribs and lagging.
For reinforcement approach, it involves the overall improvement of rock mass performance by techniques such as rock dowels, rock bolts and ground anchors. The target of reinforcement approach is to keep the rock and blocks from moving and loosening so that a large dead load of rock would not be exerted onto the support system. In fact, it holds the rock together and causes the ground around the opening to form a self-supporting ground arch around the opening.
There is a trend of tunneling industry to move from support approach to reinforcement approach because it requires less amount of structural steel support.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
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