【作者】 于飞；

【导师】 刘高；

【作者基本信息】 兰州大学 ， 地质工程， 2012， 硕士

【摘要】 西秦岭北缘断裂带是我国一条重要的NWW向区域性活动断裂和地质构造单元分界线。该断裂带位于青藏高原东北部,横跨甘、陕两省区多个县市,被甘肃引洮工程总干渠横穿。西秦岭北缘断裂带是引洮工程总干渠所穿越的最大区域性活动断裂,被穿越段隧洞围岩稳定性差,施工困难,成为特殊洞段,对引洮工程影响重大。依托甘肃引洮工程,以西秦岭北缘断裂带为研究对象,基于对漳县断裂的野外调研、室内试验和查阅文献,对西秦岭北缘断裂带空间展布、结构、物质特征和活动性进行研究,并分析断裂带对引洮工程引水隧洞地质条件的影响。研究的主要内容和结果如下。(1)西秦岭北缘断裂带平面展布具有分段性,包括3段一级破裂,6段二级破裂。断裂带纵向由一组近平行的断裂组成,剖面上呈花状构造。(2)西秦岭北缘断裂带主干断裂由一条主断层和多条与主断层产状相近性质相同的断层构成。断裂影响带由一系列不对称紧密状向斜和与主干断裂伴生的同倾或反倾的小断层构成。此外,还包括由主干断裂和伴生断层派生的小断层。(3)西秦岭北缘断裂带物质主要由断层泥和断层角砾组成。断层岩主要以褐红色、黑色和土黄色为主,粗粒含量高,粘粒含量相对较少。西秦岭北缘断裂带中段粗粒含量低于东段,其粗粒含量与粉粒含量相当。断层泥微观结构主要呈碎斑状结构、隐晶结构、分散状结构和网状结构。矿物成分以石英、方解石和高岭石为主。断层岩压缩性高,抗剪强度低。(4)西秦岭北缘断裂带形成于早古生代,晚古生代—中生代有过强烈的逆冲活动,新生代以来转变为左旋走滑为主,第四纪以来断裂垂直运动幅度很小。历史地震资料和实测断层活动位移数据显示,自晚更新世以来断裂带活动不断减弱,断裂带中段活动性强,两端活动性相对较软弱。断层泥粒度组成、显微结构和擦痕特征表明,断裂带活动具有多期性,至少经历3期次以上的活动,活动以粘滑为主,兼有蠕滑运动,断裂中段蠕滑特征较东段明显。更多还原

【Abstract】 The northern margin fault zone of western Qinling is an important NWW regional active fault zone and a dividing line of geological structure units in China. It is situated at the northeastern Tibetan plateau, relatively wide to stretch over the area of Gansu and Shaanxi, cross tunnel in Yintao project. It is the largest regional active fault zone across tunnel in Yintao project, the wall rocks of tunnel through the fault zone have a poor stability and the construction will be difficult and encounter with various geological problems.Relying on the Yintao Project, taking the the northern margin fault zone of western Qinling as the major study object, based on the field investigation and laboratory test for Zhangxian fault, reviewing literature about the northern margin fault zone of western Qinling, study on the spatial extensions, geological structure, material Character and activities of the fault zone, analyze the changes of engineering geological conditions of tunnel in Yintao project.(1) The northern margin fault zone of western Qinling is rupture segmentation, can be divided into3in firstgrade and6in second grade. It is composed by several approximately parallel faults in vertical and flower structures in the profile.(2) The northern margin fault zone of western Qinling consists of a main fault and several subsidiary faults, which are commonly arranged as en echelon (or parallel) pattern. Fracture influence zone consists of series of asymmetric compact syncline, subsidiary faults (anti-dip or cocurrent), and the derivative little faults.(3) The material of the northern margin fault zone of western Qinling consists of fault gouge and fault breccia. The fault rock which is mainly maroon, black and khak has a higher content of coarse grain than that of clay. The middle part of the fault zone with equal contents of coarse grain and silt has a lower content of coarse grain than that of the eastern part. The microstructure types of the fault gouge are mortar texture, aphanitic texture, dispergated texture and reticular texture, and the mineral composition of the fault gouge are maily quartzs, calcites and kaolinites. It has a high compressibility and a poor shear strength.(4) The northern margin fault zone of western Qinling formed mainly in early aleozoic. Based on its active characteristics, its activity is recognized as three stages, it experienced intense thrusting since late paleozoic; The transformation from thrust to left slip of northern margin fault zone of western Qinling finished in the period of the mesozoic; From quaternary on, its amplitude of the vertical movement become smaller. According to Historical Seismic Data and displacement of faulting data, since late pleistocene, fault activities continuously become weaker. And in contrast to the two ends, middle part of fault activities has a higher intensity. According to size composition, microstructure and scratch trace of fault gouge show that, it is multistage fracturing tectonism. The results suggest that it is characterized essentially by sticky slip, with some steady creeping slip.更多还原