Method of evaluating the permeability of rock mass by the combination of packer test and flowing fluid electrical conductivity log
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摘要: 进行地下水封洞库的水封条件分析评价必须获得准确可靠的建库岩体渗透性参数，而获取岩体渗透系数常用的传统水文地质试验方法存在明显的不足。为了试验数据的精确性，文章基于广义径向流（GRF）理论，依托烟台某地下水封洞工程，以丙烷洞库交通巷道钻孔为例，开展压水试验并采用非稳定流理论的GRF模型优化解析试验数据，结合电导率测井试验确定导水裂隙位置并求出裂隙范围内的渗透系数。试验结果表明：GRF模型比稳定流模型解析结果大1~2倍。原因在于裂隙岩体进行分段压水时，各段水流维度不一，传统稳定流理论假设水流维度只有二维流，而GRF模型为空间n维裂隙流用压水过程全部数据进行拟合，不同时段在相应维度下进行计算，因此其求算的渗透系数K更接近于试验段真值，具有更好的兼容性和实用性。同时利用电导率测井试验计算长度（导水裂隙范围）远远小于压水试验段计算长度的特点，可将GRF模型解析得出的分段渗透系数做进一步细化平均以提高压水试验解析结果的精度，为水封洞库效果评价、洞库涌水量预测提供更加科学可靠的数据基础。Abstract: It is necessary to obtain accurate and reliable permeability parameters of the rock mass in the analysis and evaluation of the water-sealed conditions of the underground water-sealed cavern, while the commonly used hydrogeological test methods for obtaining the rock mass permeability coefficient exist obvious deficiencies. In order to keep accuracy of the data, relying on a certain groundwater sealing reservoir project in Yantai, the paper took the propane cavern traffic tunnel drilling as an example, carried out the water pressure test and used the theory of unsteady flow of GRF model to optimize the analytical test data based on the generalized radial flow theory. The water-conducting fracture location was confirmed by the flowing fluid electrical conductivity logging test and the permeability coefficient within the fracture range is obtained. The test results show that the analytical results of GRF model is 1-2 times larger than that of steady flow model. The reason is that when the fractured rock mass is subjected to sectional water pressure, the water flow dimensions of each section are different. The traditional steady flow theory assumes that the water flow dimension has only two-dimensional flow, while the GRF model fits all the data of the pressurized n-dimensional fracture flow with the pressure water process. The time period is calculated under the corresponding dimension. Therefore, the calculated permeability coefficient K is closer to the true value of the test section, which is more compatibility and practicality. The use of flowing fluid electrical conductivity logging test will further refine the average permeability coefficient obtained from the GRF model analysis, and provide a more scientific and reliable data base for the evaluation of the effect of the water-sealed cavern.
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