土木工程与力学学院知识库

引洮工程是甘肃省有史以来最大的水利工程，属大型跨流域自流引水工程，工程地质条件复杂， 存在河床深厚覆盖层、 秦岭北缘断裂带、 深埋隧洞高地应力、白垩系及第三系红层、湿陷性黄土及饱和黄土等引起的重大工程地质问题。全面分析了引洮工程数十年积累的工程地质勘察资料及科研成果，从工程地质力学观点出发，以活动构造论和地质系统论为理论指导，对主要工程地质问题进行了分析评价。主要内容为：（1）穿越秦岭北缘断裂带 3#隧洞工程地质问题。 秦岭北缘断裂带是我国境内六条板块拼接带之一，为区域性活动断裂。总结了前人研究成果，对断裂带的平面展布、剖面结构、 活动性、 断层岩特征及与 3#隧洞的关系等方面进行了研究。认为 3#隧洞穿越该断裂带的围岩稳定性极差、施工困难。主要的工程地质问题为涌水稳定及未来断裂活动对工程运行的影响，施工中应对涌水、变形、偏压、围岩膨胀等隧洞稳定性问题给予足够的重视，并强化施工地质超前预报、动态设计与信息化施工。（2）九甸峡水利枢纽坝址河床深厚覆盖层的工程特性。 坝址区河床狭窄，存在河谷深槽。河床覆盖层厚度一般为 40~50m，最大厚度 54~56m。按其颗粒组成和结构分为三层，上层因不宜作为大坝基础，应予挖除，重点对中、下层进行了研究。对于覆盖层的基本物理力学特性主要依据钻孔取样、室内试验、压试验和载荷试验综合确定。对河床深厚覆盖层上坝基稳定性做了分析评价，并基于岩体赋存环境和岩体几何完整性对河谷深槽及河床深厚覆盖层的形成机制作了研究。研究区的主要工程地质问题是渗透稳定性与振动液化。（3）白垩系及第三系红色碎屑岩隧洞围岩稳定性问题。 总结了我国红层的分布特征，对甘肃红层的基本特征做了论述；评价了红层的物质组成、物理性质、水理性质、力学性质等工程地质特征。认为引洮工程的红层承载力低、变形较大。主要工程地质问题是抗风化稳定性与工程岩体开挖保护措施、沉降变形、膨胀性、渗漏、抗冲刷、抗滑稳定性及环境水对混凝土的侵蚀性。对隧洞的稳定性做了分析计算，其稳定性主要受围岩强度、含水率和初始应力等控制，变形破坏形式主要表现为塑性变形破坏，宜采用新奥法进行施工。（4）饱和黄土隧洞施工技术问题。总干渠末端的13#、14#、15#隧洞位于饱和黄土分布区，累计全长5608 m。测试并论述了饱和黄土的粒度成分、化学成分、矿物成分、微观结构等方面与工程特性的关系，用Drucker-Prager弹塑性模型与关联流动法则，模拟了传统钻爆法开挖时的隧洞稳定性。结果表明，围岩稳定性很差，施工应采用盾构法施工工艺。

Yintao project, which is a large scale flowing automatically diversion conservancy project across different drainage areas, and is the biggest water project in Gansu province. Its engineering geological conditions are very complicate, including the great and big engineering geological problems brought by the deep and thick covers of riverbed, the fault zone of the northern margin of Qinling, the high stress of deep-buried tunnel, the red stratums of the Cretaceous and the Tertiary, the collapsible Loess, the saturated loess etc. Through the comprehensive analysis of the engineering investigation datum and the results of scientific research of the “Yintao” project accumulated over the last several decades, the main engineering geological problems be analyzed and evaluated basing on engineering geological and mechanical view, and geological and structural theory and geological system theory. The main contents are as below:
（1） Engineering geological problems of 3# tunnel across the fault zone of the northern margin of Qinling. The fault zone of the northern margin of Qinling is one of the six plates strips combination in China and is a regional active fault zone. Summarized up the results of past study, the distribution in earth surface, the structure in section, activities, the fault rock features of the fault zone, the relation with 3# tunnel and other aspects have been researched. It has concluded that the wall rocks of 3# tunnel through the fault zone have a poor stability and the construction will be difficult. The main engineering geological problems include the stability, washing, and the influence of the future faulting activities on the project, we should pay more attention to the gushing water, deformation, declination press, the expandability of wall rocks and other problems about stability and emphasized geological prediction, adjusting design and construction according to conditions in situ..
(2) Engineering properties of the deep and thick cover of riverbed in “Jiu-dian-xia” dam site. The dam site has a narrow riverbed and deep trench. The general thickness of the riverbed cover is 40～50m, and the maximal thickness is 54~56 m. According to its particle composition and structure, the cover can be divided into three layers, the upper one should be excavated because it is improper to be foundation, so it should be pay more attention to the study on the middle layer and substratum. Basing on the drilling and sampling, laboratory test, lateral pressure test and loading test in situ, the basic physical and mechanical properties of the cover be determined comprehensively. Then the stabilities of the dam foundation on the thick and deep riverbed cover be analyzed and evaluated, and the formation mechanism of deep trench and the thick cover of the river be researched through the environments of rock mass and its geometric integrity. The main engineering geological problems in project area are infiltration, stability and vibration liquefaction.
（3） The problem of tunnel stability which is made up of detrital rock of Cretaceous and tertiary: it summarized distributing characters of red stratums in China, basic described characters of red stratums in Gansu; and estimated its geological engineering characters, such as components, the physical, mechanical and hydrological properties, etc. It have been confirmed that red stratums is low bearing capacity, and large deformation. The main geological engineering problems are weathering, deformation, dispensability, leakage, washing, sliding, water erosion. It has been proved that stability of tunnel is mainly controlled by intensity of rock wall, water content and initial stress, and the type of deformation is of plastic, and NATM technology will be adopted in the construction of tunnel.
（4） The problem of constructing technology on tunnel which is made up of saturated loess: No.13-15 tunnels of main cannel are located on saturated loess and 5608 meters in length. It examined and discussed relationship between engineering properties and granularity, microstructure, chemical and mineral ingredients. It also analogized stability of tunnels by traditional method with principal of Drucker-Prager associated flowage. As a result, the rock wall is very weak and shield structured method must be adopt in the construction.