Contractor Beijing Vibroflotation Engineering used a 7.9m-diameter Robbins main beam TBM to excavate rock types ranging from tuff to granite, sandstone, and andesite with multiple fault zones, with strengths from 35 to 206MPa. Almost continuous rock support was needed and The machine bored through a total of 24 fault zones utilizing a unique combination of steel McNally slats (extruded through pockets in the TBM roof shield to prevent movement of loose rock), wire mesh, and shotcrete.
Wu Zhi Yong, vice chief engineer for the contractor said that advance rates peaked at 1,423m per month and were over 1,000m per month for three consecutive months, adding “I am so proud of this achievement.”
