Method and apparatus for starting a tunneling machine from an initial placement within a vertical shaft sunk into the ground and provided with a starting port

摘要

A method of and apparatus for starting a tunneling operation into a soft ground having a high water content or much gushing water while preventing any collapse of the ground or outflow of water. The tunneling machine is initially placed within a vertical shaft in the ground and a sheet pile is struck into the ground between a retaining wall of the shaft having a starting port through which the machine is to be ultimately advanced into the surrounding ground after the port is opened by raising the pile. A ring-shaped liquid-tight packing is applied to the retaining wall and surrounding the starting port engages the periphery of the head portion of the tunneling machine to form part of a liquid- pressurized chamber in front of the machine, the pressure in the chamber being at least as high as the surrounding underground water or ground pressure when the port is opened and the machine is then started through the port.