隧道盾构-毕设论文外文翻译（翻译+原文）.doc

1 SHIELDS 【 Abstract 】 A tunnel shield isa structural system, used during the face excavation process. The paper mainly discusses the form and the structure of the shield. Propulsion for the shield is provided bya series of hydraulic jacks installed in the tail of the shield and the shield is widespread used in the underground environment where can not be in long time stable. The main enemy of the shield is ground pressure. Non-uniform ground pressure caused by the steering may act on the skin tends to force the shield off line and grade. And working decks inside the shield enable the miners to excavate the face, drill and load holes. 【 Keywords 】 shield hydraulic jacks ground pressure steering working decks A tunnel shield isa structural system, normally constructed of steel, used during the face excavation process. The shield has an outside configuration which matches the tunnel. The shield provides protection for the men and equipment and also furnished initial ground support until structural supports can be installed within the tail section of the shield. The shield also provides a reaction base for the breast-board system used to control face movement. The shield may have either an open or closed bottom. Ina closed-bottom shield, the shield structure and skin provide 360-degree ground contact and the weight of the shield rests upon the invert section of the shield skin. The open shield has no bottom section and requires some additional provision isa pair of side drifts driven in advance of shield excavation. Rails or skid tracks are installed within these side drifts to provide bearing support for the shield. Shield length generally varies from1/2 to 3/4 of the tunnel diameter. The front of the shield is generally hooded to so that the top of the shield protrudes forward further than the invert portion which provides additional protection for the men working at the face and also ease pressure on the breast-boards. The steel skin of the shield may vary 2 from 1.