土木工程专业英语第二版(段兵延)lesson14

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1、HowTunnelsAreBuilt如何开挖隧道Afterthegeneraldirectionforatunnelhasbeendetermined,thenextstepsareageologicalsurveyofthesiteandaseriesofboringstoobtainspecificinformeitiononthestratathroughwhichthetunnelmaypass•Thelengthandcrosssectionofatunnelgenerallyarcgovernedbytheus

2、eforwhichitisintended,butitsshapemustbedesignedtoprovidethebestresistancetointernalandexternalforces.Generally,acircularornearlycircularshapeischosen.在一条隧道的大致方向定下来之后，下一步就是调查隧道沿途地层的钻孔资料并获取具体的地层信息。隧道长度和横断面通常由其用途决定，但是其形状必须设计成对内外荷载产生最佳抗力的形式。通常会选择圆形或近似的圆形。Inveryhardroc

3、k,excavationusuallyisaccomplishedbydrillingandblasting.Insofttomedium-hardrock,atunnel-boringmachinetypicallydoestheexcavatingwork.Tnsoftground,excavationusual1yisaccomplishedbydiggingorbyadvancingashieldandsqueezingthesoftmaterialintothetunnel.Inunderwatertunneli

4、ng,ashieldisusedtoadvancethework.Anothermethodofbuildinganunderwatertunnelistosinktubularsectionsintoatrenchdugatthebottomofariverorotherbodyofwater.在非常坚硬的岩石中，通常采用钻机和爆破廿挖。在软弱到中硬岩石，采用隧道挖掘机是典型的开挖方式。在软弱土层，通常采用盾构和挤压软弱土质的方式向前推进。在所有岩石或土层的开挖方式中，淤泥土要被收集起来运出隧道。在开挖水下隧道吋，要采用

5、盾构向前推进。另一种开挖水下隧道的方法是将深管放入河底或水中其他位置的已开挖的深沟中。Hard-rocktunneling•Shortturrncisthroughhardrockarcdrivenonlyfromtheportals,butlongeronesusuallyaredrivenalsofromoneormoreintermediateshafts•SomelongtunnelshavebeenbuiItwiththeaidofasmallpilottunneldrivenparalleltothemaint

6、unnelandconnectedwithitbycrosscutsatintervals.Thepilottunnelnotonlyfurnishesadditionalpointsofaccessbutalsoarouteforremovingmuckandforventilationductsanddrainageline.硬岩隧道穿过硕岩石短隧道仅从入口开挖，但是较长的隧道通常是从一个或几个地方同时开挖。有些长隧道是在平行于主隧道开挖的小型导洞辅助下建造的。导洞与主隧道Z间每隔一段距离由横巷连通。导洞不仅是通道的附

7、属设施也是运土，通风，排水的通路。Anothermethodistheheading-and-benchsystem,formerlyusedonmostlargetunnelsbecauseitrequiredsmalleramountsofpowderandpermittedsimuItaneousdrillingandmucking(removalofexcavatedmaterial).Theupperportionofthetunnelisdrivenaheadofthelowerpartwhichiscalle

8、dthebench•Aseparatecrewisthusabletomuckinthelowerportionofthetunnelwhiletheupperportionisbeingdrilled.另一种方法是采用正台阶开掘系统，以前被用于大型隧道因为它仅要求更少的火药并且允许同吋钻孔和运土(转移