Abstract:

From consolidating similar past case studies with regards to the problems encountered during construction phase, this article is able to provide an important point of view on shield tunnel design in gravel layer. which is different from that in soil layer. Some common problems consolidated into the article are the barrier faced due to the presence of large boulders, the higher wear and tear rate of the cutting head, the settlement problems due to boring, the selection of best shield machine, etc. This article also comprised examples of shield tunneling in gravel layer mostly from Taiwan and Japan, the characteristics of the gravel layer, the design considerations and the proposal brought forward. Besides that, the article also consists of problems associated with shield tunnel design in gravel layer such as: 1) the site investigation's content and objectives; 2) the design analysis including the considerations, the selection of the suitable shield machine, precaution taken with regard to the stabilization of the excavation site, backfill grouting, ground improvement, removal of barrier found within the soil, the characteristic of the settlement during boring ,etc. The article can be used for future reference in the certain engineering projects..

Key words: gravel layer  , shield tunneling