摘要
渗透系数是表征裂隙岩体透水性能的一个重要参数,当水压力较小时,岩体的渗透系数变化不明显,但在高水压力条件下,岩体的渗透系数会发生明显变化,这给我们在进行渗流分析时带来了一定的困难,因为多数情况下是将渗透系数当作定值来计算的。在高压水条件下,基于非达西流方程,推导了裂隙岩体的渗透系数与水压力之间的表达式,并给出了常规压水或低水压力、高压压水时水力劈裂前后渗透系数的计算公式。现场压水试验结果表明,当岩体发生水力劈裂后,渗透系数增加明显,此时可以通过压水量和水压力的变化量来计算裂隙岩体的渗透系数。通过几个抽水蓄能电站的高压压水试验结果验证了裂隙岩体水力劈裂前后渗透系数的变化规律,并与实际裂隙岩体的渗透系数进行了比较,其误差在10%左右,表明本文给出的渗透系数表达式的合理性和准确性,为水利水电工程的渗流分析及渗漏量的计算提供了渗透系数选择的依据。
Hydraulic conductivity is an important parameter to describe the permeability characterization of fractured rock mass. It is often determined using the water pressure tests of borehole in hydraulic and hydro-power engineering. When the water pressure is very low,the permeability variation of rock mass is not obvious owing to its integrity and strength. But under high water pressure,its permeability would change obviously. The main reasons are that fractured apertures can be increased,some close fractures may be re-opened,and the small and unconnected fractures are penetrated between each other under the action of high water pressure. Changes of permeability would lead to some difficulties for seepage analysis,because hydraulic conductivity is often considered to be constant. The calculated hydraulic head and flux have great errors if the variation of permeability coefficient hasn't been considered. On the condition of high water pressure,the relationship between hydraulic conductivity of fractured rock mass and water pressure is deduced according to the Non-Darcy flow equation in this paper. Three equations for calculating hydraulic conductivity are provided here. The first equation is applied to the condition for low water pressure. The results of field water pressure test show that when the hydraulic fracturing of rock mass occurs,hydraulic conductivity increases obviously. It can be calculated through the variation of water flux and water pressure. In this paper,variation characteristics of permeability coefficient before and after hydraulic fracturing are verified using the results of high pressure water test from pumped storage power stations. Field test results are used to calculate hydraulic conductivity of rock mass. A comparison is conducted for measured and calculated hydraulic conductivity values to validate the rationality of deduced equation. The errors between measured and calculated values are less than 15 percent and the average error is about 10 percent,which show the calculated hydraulic conduct
作者
黄勇
周麟桐
周志芳
HUANG Yong;ZHOU Lintong;ZHOU Zhifang(School of Earth Science and Engineering,Hohai Unviersity,Nanjing 210098)
出处
《工程地质学报》
CSCD
北大核心
2018年第6期1433-1438,共6页
Journal of Engineering Geology
基金
国家自然科学基金(41572209)
江苏省青蓝工程项目(2016B16073)资助
关键词
高压压水试验
裂隙岩体
水力劈裂
渗透系数
High water pressure test
Fractured rock mass
Hydraulic fracturing
Hydraulic conductivity
