| 摘要 |
PURPOSE:To reduce an opened and excavated area and to make it possible to execute a widening section by arranging freezing pipes on a pipe roof constructed in a tunnel, forming a frozen ground to cut off, removing segments, excavating the frozen ground, and installing shores successively. CONSTITUTION:Pipe roofing steel pipes 12 for forming a widening section in a tunnel 7 from a vertical shaft 5 are burried into a bedrock 3. At that time, a cutter 16 of an excavator is inserted through a driving jack and a pushing ring while rotating and driving it, a filler 25 is supplied to the inside thereof to withdraw the excavator, and a pipe roof 11 is formed in a state to surround the tunnel. After that, two freezing pipes 26 are arranged to the insides of the steel pipes 12, freezing pipes 27 are arranged from the inside of the tunnel toward the steel pipes 12, and a frozen ground 3c is formed to cut off. The withdrawal of segments 9, the excavation of the frozen ground 3C and the installation of shores are successively carried out to execute a specific widening section. According to the constitution, an opened and excavated area can be reduced to carry out a widening work of the deeper depth safely. |
