Decision-making approach for parallel earth pressure balance machine advancements for tunnel construction

Tunnel excavation with Tunnel Boring Machine is more systematic and safer due to in house deformation control by operator but when excavation done for parallel tunnels then tunnel construction became more slower because any one tunnel excavate entirely then go for 2nd tunnel to avoid this delay in tunnel excavation in this study highlights the influence of two parallel (||) TBM construction processes when this two TBMs Tunnel Boring Machine) which is used to excavate tunnel in numerical model. 7 construction sequences (decisions) where adopted for checking its feasibility in parallel tunnel construction simultaneously. In this study Excavation Cycle Sequence (ECS) introduced for representing excavation of tunnel and they are ECS-D1, ECS-D2, ECSOEO, ECS-EOO, ECS-OM. All this ECSs complete tunnel excavation in different excavation cycles which are nothing but excavation for ring or rings as per ECS also installation and applicable for that particular ECS. This study shows that if adopt time dependent excavation (time=more or less installation of rings in numbers) make influence on deformation pattern between (ux=lateral deformation) parallel tunnels as well as in vertical deformation (uz). In tunnel advancement direction (uy= longitudinal deformation) as per excavation and installation of rings in Plaxis 3D model are constant (0.59mm) deformations because of applica-tion of constant thrust force which is required for the TBM movement in construction advancement direction (along +Y=axis) in Plaxis 3D model, we will suggest to implement variable thrust force models for further studies. This study shows that to minimize deformation use minimum excavation cycle such as ECS-OEO (Odd Even Order) and ECS-EOO (Even Odd Order), and if excavation cycle increases for more safer construction approach such in adverse geological sections in underground simultaneous excavation of parallel tunnels then increase drift (distance between excavation faces) to minimize deformation such as in ECS -OM (4.6m).