Case Study on Hard Rock Treatment Technology and Shield Docking Technology in Boring of Underwater Tunnels

The treatment of special ground encountered during underwater shield tunneling is summarized.The shield docking technology adopted in boring of underwater tunnels is presented.Main difficulties of shield tunneling in heterogeneous ground,boulder ground and gravel ground,as well as the corresponding countermeasures,are analyzed.In the shield tunneling through slightly-weathered hard granite ground and weathered boulder ground in the construction of the water conveyance tunnel of Taishan Nuclear Power Station,underwater blasting technology and impact drilling technology for bedrocks and boulders are applied.The shields have successfully passed through the bedrock section,without cutting tool replacement.In the construction of Shiziyang underwater tunnel,shield docking technology is adopted.The docking has achieved good result,the rock mass at the docking point is stable and the docking accuracy is high.