Study on Rock Cutting Mechanism and Efficient Shield Tunneling Control in Mixed-Ground with Different Strengths

Mixed ground condition exerts very significant influences on the rock fragmentation mechanism, rock cutting efficiency, and operational parameters selection of the shield boring machine. In order to reveal the rock cutting mechanism when the shield tunnel boring machine advances through the mixed grounds in Line 13 of the Shenzhen Metro Tunnels, according to several linear cutting tests were conducted using a constant cross-section disc-cutter and five rock types with different strengths. The change of disc-cutter cutting force and rock boreability index were analyzed, and some suggestions were proposed to fulfill the safe and efficient tunneling of the shield machine in mixed ground conditions. The results of this study can offer useful suggestions for the operation parameter selection of the shield tunnel boring machine tunneling through the mixed ground in the Shenzhen Metro Line 13 and similar projects.