| 摘要 |
<p>The tunnel boring system is particularly for use in soft ground and at shallow depths, and where solid obstacles will be encountered. A tunnel-shaped working chamber is driven into the ground, and behind it tunnel sections of the same external diameter are installed in succession. The working chamber (1) is divided into a top part permanently sealed by a shield (4) equipped with soil-loosening tools (5), and a bottom part with front and rear sections connected together. An air pressure vessel is provided to keep the top part under pressure.</p> |
