Rock-Properties Estimation by TBM Cutting Force

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5. Culter-Goodman Tunnel

Nelson (1983) reported the excavation data for the Culter-Goodman tunnel in New York. The tunnel was excavated using a 5-m TBM. This data includes geological boundary, which consists of Maplewood shale (average compressive strength = 68 MPa) and Reynales limestone (130 MPa). The inclined angle between the geological boundary and the tunnel axis is 45 degrees, rock of the face changed from Maplewood shale to Reynales limestone as the TBM advanced. The ratio of Raynales limestone at the face is divided into four sections: 0-30%, 30-60%, 60-90%, and 90-100%. Average thrust and penetration are also reported. The relationship between estimated rock strength and the ratio of Raynales limestone at the face is shown in Fig. 6. In Equation (5), c1 is defined by the average strength and cutting depth at Maplewood Shale. As the ratio of Raynales limestone at the face increased, estimated rock mass strength increased. When the ratio reached 95%, the estimated rock mass strength was found to be 135 MPa, approximately equal to the compressive strength of Reynales Limestone (130 MPa). For the geological boundary, rock strength estimated using Equation (5) agreed well with the rock mass.