Shield tunneling method and machine therefor

A shield tunneling method comprising the steps of;

• excavating tunnel face by a cutter head (24,124) provided at the front of a shield body (10,110) to be thrusted and allowing the passing of the muck therethrough;
• filling said muck mined at the tunnel face between the tunnel face and a diaphragm (14,114) disposed across said shield body and usually maintained closed by an operating means (52,160) and provided with a chamber (48,142) behind said diaphragm, said chamber being filled with a liquid;
• pressurizing said muck by forwardly thrusting said shield body, thereby exerting a pressure on the tunnel face with said muck under the pressurized condition;
• allowing admission of said muck into said chamber filled with the liquid by opening said diaphragm with said muck, when said pressure is increased to a level higher than a predetermined pressure which is preset at said operating means and which is higher than an active earth pressure in the face ground but lower than a passive earth pressure;
• and
• discharging the liquid containing said muck out of said chamber while said liquid is being supplied into said chamber.

A shield tunneling machine comprising;

• a drive shaft (26,126) rotatably carried by a diaphragm (14,114) provided in the front portion of a shield body (10,110) to be thrusted;
• a cutter head (24,124) attached to the end of said drive shaft and allowing the passing of muck therethrough;
• a muck chamber (48,142) defined behind said diaphragm;
• a muck inlet (16,116) provided in said diaphragm;
• a cover member (50,148,149) adapted to open and close said muck inlet;
• an operating means (52,160) adapted to exert on said cover member a pressure of a predetermined level higher than an active earth pressure in the face ground but lower than a passive earth pressure, thereby displacing said cover member to close said muck inlet, and adapted to displace said cover member to open said muck inlet when the pressure acting on said diaphragm and said cover member by the muck admitted into said shield body is raised over said predetermined level;
• means (66,143) for supplying a liquid into said muck chamber, so that said muck chamber is usually filled with the liquid;
• and
• means (56,144) for transporting the liquid containing the muck out of said muck chamber.