基于钻孔充气试验的岩石渗透率原位测量研究

基于稳态气体渗流理论推导了岩石渗透率原位测量公式,基于巴甫洛夫斯基雷诺数公式给出了工程中达西渗流的粗略判断方法,研制了一套由气源子系统、气体质量流量控制子系统、封孔子系统、气体压力测量子系统组成的岩石渗透率原位测量系统,介绍了各子系统的组件及功能,给出了测量步骤和流程,形成了基于钻孔充气试验测量岩石原位渗透率的完整方法,在某场地花岗岩介质中开展了原位钻孔充气试验,得到了现场钻孔的原位渗透率数据,并对试验中的钻孔压力历程、达西渗流判断、充气流量影响、胶塞膨胀压力影响、测量结果代表范围等关键环节进行了深入分析。试验结果表明该系统稳定性好,测量结果合理且代表范围大,能够应用于岩石渗透率的原位测量中。

In-situ measurement of rock permeability based on pneumatic tests in boreholes

The in-situ measurement formula for rock permeability is derived based on the theory of steady gas seepage. A rough judgement method for Darcy seepage in engineering is given based on the Pavlovsky’s Reynolds number formula. An in-situ system to measure rock permeability is established, which consists of gas source subsystem, gas mass flow control subsystem, sealing subsystem and gas pressure measurement subsystem, and the components and functions of each subsystem are introduced. The measurement flow and steps are given. The complete method of in-situ measurement of rock permeability based on pneumatic tests in boreholes is formed. The in-situ pneumatic tests in boreholes are performed in granite medium at a certain site. The in-situ permeability of field holes is got, and some key aspects in the tests are analyzed, such as pressure course in boreholes, judgment of Darcy seepage, influence of pneumatic mass flow, influence of stopper’s expansion pressure and representative area of measurement data. The results show that the stability of this system is good, and the measurement data are reasonable and have a large representative range. The proposed system can be applied to the in-situ measurement of rock permeability.