隔河岩电站引水隧洞群洞开挖研究

Excavation of Inlet Tunnels at Geheyan Power S tation

The Geheyan Power Station on the Qingjiang river has four inlet tunnels, on the right bank, with its excavation diameter of 11.3 m to 12.5 m, after-lining diam eter of 9.5 m, axis-to-axis spacing of 24 m. The thickness of the pillar betwe en tunnels should usually be more than two times of tunnel diameter to ensure th e stability of surrounding rock during excavation. In this paper, the excavation methods of tunnels with the pillar thickness as small as the tunnel diameter, s uch as smooth surface blasting, shotcrete support protection, are emphatically d iscussed.