【作者】 唐红侠；

【导师】 周志芳；

【作者基本信息】 河海大学 ， 水文学及水资源， 2005， 博士

【摘要】 我国的水电开发处于前所未有的黄金时期,使得一批大型、特大型的水利水电工程开始兴建。这些高坝大库坐落在裂隙岩体之上,蓄水后坝基裂隙岩体将面临很高的外水压力,那么它们能否承受这么高的水压力?这取决于坝基岩体中的裂隙在高水压下的稳定性及渗透性,它关系着整个工程的安全与否。为了解决这类问题,把水力劈裂的理论和技术引用到该领域,对这类问题进行了探索性研究;而水力劈裂理论在评价坝基岩体中裂隙的稳定性方面的研究还较薄弱。故论文的选题具有理论意义和实用价值。 本论文以已有的水力劈裂理论为基础,以原位水力劈裂试验结果为依据,以峡谷区天然条件下的裂隙为对象,用构造地质学、岩石力学、地下水动力学及线弹性断裂力学的理论及方法来研究水力劈裂过程中裂隙的发生、发展过程,以及在该过程中裂隙的渗透性规律,并给出了水力劈裂过程的机理分析。最后结合工程实际进行应用。 本文通过对原位水力劈裂试验结果分析发现:影响岩体劈裂压力的根本原因在于岩体内是否存在裂隙及已存在裂隙的规模。作者完善了水力劈裂过程的三阶段:裂隙起劈阶段、裂隙生长阶段和裂隙稳定阶段,指出裂隙生长阶段的结束应以流量的衰减作为标志。利用无量纲化的方法研究表明:在水力劈裂过程中的裂隙起劈阶段:裂隙宽度—水压力关系及裂隙渗透性—水压力关系均为对数关系;在水力劈裂过程中的裂隙稳定阶段:裂隙宽度—水压力关系及裂隙渗透性—水压力关系均为线性关系。论文从机理上对水力劈裂过程进行分析,通过固体力学分析得出:水力劈裂过程与裂隙的压裂过程之间在变形机理上有着本质的区别。水力劈裂过程只有弹性变形和脆性破坏,不存在裂隙压裂过程中的第三种变形机理—压缩破坏。通过流体力学分析得出:在裂隙起劈阶段,地下水流的流态为紊流,且J-v之间满足指数关系;在裂隙稳定阶段,地下水流的流态较为接近层流状态。另外,论文还分析了在应力(正应力)作用下裂隙介质中裂隙的倾角对渗流的影响,即裂隙面的倾角效应。最后,因为水电工程自身的特点:蓄水后地应力与试验条件下的地应力区别很大,再加上本次水力劈裂试验的局限性,故在进行工程应用时,只能得出近似的结果。但是该结果仍然对本文中的水利水电工程以及类似的水利水电工程具有指导意义。更多还原

【Abstract】 Now exploitation of hydraulic electricity is at the height of power and splendour in China, and many larger-scale water power stations will be built up. The foundations of these high dams are crack rocks, after big reservoirs impounding, high hydraulic pressure will be put on the crack rocks, and can they bear the high pressure? The stability and permeability of dam foundation rock cracks determine the project’s safety. In order to meet water power stations’ need, the author applies hydraulic fracturing to this field and research into these problems. But, applying hydraulic fracturing to evaluation the stability and permeability of dam foundation rock cracks is a vacancy in our knowledge. So, the selected topic of thesis has important value in theory and practice.On the basis of previous hydraulic fracturing theory, according to hydraulic fracturing field experiments and with natural cracks in gorges as initial conditions, using the theories of Tectonics, Rock mechanics, Dynamics of groundwater and Fracture mechanics, the paper researches laws of the fracture initiation, fracture growth & crack stability, its permeability in the process of hydraulic fracturing, and analyzes the mechanism of hydraulic fracturing. At last, applying the theories to a project.Analyzing of the results of hydraulic fracturing field experiments, determination pressure of rock fracture initiation is the crack size. According to the injection rate and pressure in the process of hydraulic fracturing, the representative modeling of hydraulic fracturing process is designed as a process with three stages: crack initiation, fracture growth and fracture stability. The flow reduce is the symbol of fracture growth stage. Using dimensionless method, the paper concludes that at the stage of crack initiation, the relation of aperture & hydraulic pressure is log law and the relation of fracture’s permeability & hydraulic pressure is log law too, and that at the stage of fracture stability, the relation of aperture & hydraulic pressure is linear law and the relation of fracture’s permeability & hydraulic pressure is linear law too. The paper analyzes the process of hydraulic fracturing on mechanism, realizing the processes of hydraulic fracturing and crack initiation under normal stress have difference on deformation mechanism. There are only elastic deformation and brittle deformation on the process of hydraulic fracturing, and not compaction. At the stage of fracture initiation, the groundwater is turbulent flow, and the relation of J - v is an exponential expression. At the stage of crack stability, the groundwater is approximately laminar flow. In the paper, the seepage under stress shows the obliquity effect. Finally, because the characteristic of water power stations: the significantly difference of the principle stresses before and after reservoirs impounding, and the non-perfectly hydraulic fracturing field experiment, the paper approximately applies conclusions into a water power station. But the results still have the important value to this project and similar projects.更多还原