大断面黄土隧道稳定性参数指标分析

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1、铁道科学研究院硕士学位论文采用弯压组合对截面进行极限承载力判断。埋深15m围岩压力分布形式时，墙腰处截面容易发生破坏，为整个支护结构的控制截面，埋深70m围岩压力分布形式时，墙脚附近截面更容易发生破坏，可作为支护结构的控制截面。5、在对型钢喷射混凝土进行抗压区高度确定时，截面中和轴有大幅上移，中和轴通常不通过型钢腹板而通过型钢上翼缘中心。6、截面厚度对支护结构极限位移的影响比材料弹性模量大的多，是因为在结构刚度j汀的表达式中，占是线性关系，而厚度日是三次函数关系。采用高弹性模量材科、增加截面厚度对减少极限位移有利，

2、但结构所受的内力较大。在围岩压力、截面厚度一定的条件下，支护结构极限位移与材料弹性模量为近似的双曲线关系。4铁道科学研究院硕士学位论文ABSTRACTUndefgr0瑚dconstructionwouldpIayaIeadingrolein21。ccnmly’s姗咖cfion；railway鼬ctionwouldbethemainmediuminurIdergroundcofI咖嘶otl'who∞design柚dcons虮lctionprovidesvaluableexperierIcefordevelopmemo

3、fdomesⅡc岫de唱roundstructures．Asp黜ngerdedicatedImes(PDL)havebeencommencedinalargescale，geologicalconditiomforPDLbecomemoreandmotecompIicatedanddifficulkwherein10esstunnelsforPDLwouIdbethemosttypicalexample．Bigcro翳-sectiontunnelscm'tentlyconsistofsix-l粕ehighway10

4、essmnnelsandfailwayPDLlocssm仰els；failw科PDLIocsstllnnelshavemuchbi鹳ercrosssecfiomthan∞rmalfailwaysbecauseof∞rodyn锄icsado啤dforloesstunneIsandcr0髂∞ctio邮a∞genemllyla曙e—sp柚nateIlip∞·sh印edu，hichisdi位删疗0m∞malmilwaytunnelsandh讪w科tunnels，b0曲Ofwhichmeansthatloesstunnels

5、a∞quitedi恐rent丘DmnormaltunnelsiIl觚sofexcaVation．∞nstructionsupportanddef．omaⅡonduringco-supponofmcksandattificialⅫpport．Loessc讲l曲nJ鲥彻is．mi协iIlitialstageallovertlleworldwithnopr州。惦e)【p耐ence王nd龉i口orco∞仃1删oll'thereforejudgingstabilityforbigcross-scctionloesstunne

6、lssllallbeconsider酣s甜ouslyHowever,no丌nalcfitedafortunnelstabilitysuch硒m畎strengthandrock朋e呵Vari鲥onwouldnotbefittabktojudgeloesstunnelsstabil时dl坞tospecialkaturesofIo妫stunnels．Dome鲥cmonitoringsystemswhe他movem铷tmeas咖playstheleadingroleandmomtoringfeedb∞k∞searcllcs

7、havebeenwell5铁道科学研究院硕士学位论文developedrecently：ineightnecessarymonitoringitemsspecifiedinConstructionTechniqueInstructionsforPDLTunnels，sixitemsbelongtomoverneatmeasuringitemsexceptthetwoitemsofinnertunnelobservationandoutertunnelobservation．Apparently,structurem

8、ovementisstillthemaincriterionforbigcross-sectionloesstunnelsstabilityjudgment．Thewayofbigcross-sectionloesstunneldeformationdiffersmuchfromthatofthenormaltunnelduetopoorrockbearin