高压条件下岩体渗透系数取值方法研究
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摘要
裂隙岩体在高水压条件下的渗透性可以通过高压压水试验获得。高水压状态下裂隙岩体中水流形态及渗流本构律对岩体渗透系数起决定性的影响。针对高水压状态下岩体中渗流形态为紊流和非达西流的实际情况,以高压压水试验中压水孔内的水压力和流量以及渗压孔内的孔隙压力等参量为基础,推导了单孔三段压水法和单孔单段压水法的裂隙岩体渗透系数计算公式。结合某抽水蓄能电站高压压水试验成果深入分析了不同渗流形态下的岩体渗透系数的差异性。研究成果表明,裂隙岩体水流形态对岩体渗透系数定量取值结果影响较大,同时高水压条件下水力劈裂产生也将导致裂隙岩体渗透系数取值的急剧增加。
Permeability coefficient of fractured rock mass under high pore pressure condition could be obtained through high pressure permeability test (HPPT).The constitutive law and flow pattern of water flow in rock mass under high water pressure are the main factors for determinating permeability coefficient.Based on the fact that water flow in rock mass under high pressure condition belongs to turbulent flow and the Darcy’s law is not available anymore,the formulas for calculating the high pressure permeability coefficient at different experiment methods are deduced according to the pressure and discharge in the water injection borehole and pore water pressure in the monitor borehole.The difference of permeability coefficient at different flow pattern is discussed based on the experimental results of the Heimifeng Water-Pumped Storage Power Project.It indicates that permeability coefficient of turbulent flow in fractured rock mass is far more than that of laminar flow and the hydraulic fracture will lead to the sharp increase of permeability coefficient under high pressure condition.
Permeability coefficient of fractured rock mass under high pore pressure condition could be obtained through high pressure permeability test (HPPT).The constitutive law and flow pattern of water flow in rock mass under high water pressure are the main factors for determinating permeability coefficient.Based on the fact that water flow in rock mass under high pressure condition belongs to turbulent flow and the Darcy’s law is not available anymore,the formulas for calculating the high pressure permeability coefficient at different experiment methods are deduced according to the pressure and discharge in the water injection borehole and pore water pressure in the monitor borehole.The difference of permeability coefficient at different flow pattern is discussed based on the experimental results of the Heimifeng Water-Pumped Storage Power Project.It indicates that permeability coefficient of turbulent flow in fractured rock mass is far more than that of laminar flow and the hydraulic fracture will lead to the sharp increase of permeability coefficient under high pressure condition.
引文
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[2]郭启良,安其美,丁立丰.高水头电站钻孔高压压水的作用和意义[C]//地壳构造与地壳应力文集13.北京:地震出版社,2000:148-154.
[3]蒋中明,傅胜,李尚高,等.高压引水隧洞陡倾角断层岩体高压压水试验研究[J].岩石力学与工程学报,2007,26(11):2318-2323.
[4]郭启良,王海忠,张志国.小天都水电站气垫调压室洞壁围岩的高压透水性测量研究[J].水力发电学报,2005,24(1):102-106.
[5]SL31-2003,水利水电工程钻孔压水试验规程[S].
[6]沈洪俊,张奇,夏颂佑.裂隙水流规律试验研究进展[J].河海科技进展,1994,14(3):34-38.
[7]钱家忠,赵卫东,潘国营.单一流迳基岩裂隙水流态的实验研究[J].焦作工学院学报(自然科学版),2005,19(3):192-195.
[8]丁留谦,许国安.三维非达西渗流的有限元分析[J].水利学报,1990(10):49-54.
[9]蒋中明.黑麋峰抽水蓄能电站高压岔管段F15断裂带高压压水试验研究报告[R].长沙:长沙理工大学,2007.
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