基于压水试验的均质含水层渗透系数计算方法

Method of Calculating Permeability Coefficient Using Water Pressure Test in Homogeneous Aquifer

从常规吕荣值计算公式出发,分析了用压水试验中的吕荣值作为衡量岩体透水能力定量指标存在的不足,推导出均质条件下压水试验中稳定流和非稳定流状态下的渗透系数计算公式。该公式完善了压水试验数据的分析计算法。选取锦屏一级水电站帷幕灌浆检测孔实测压水数据,采用稳定流及非稳定流方法分别计算其渗透系数,结果表明在短历时压水中采用非稳定流方法计算的渗透系数小于稳定流的计算值。因此,采用非稳定流计算的结果准确性较高。

On the basis of the formulae for the Lugeon value, the shortage of Lugeon as a quantitative indicator ofrock permeability in water pressure test is analyzed. By deducing the calculation formula of permeability coefficient with steady flow and unsteady flow in homogeneous postulation water pressure test, we believe that the accuracy of calculation result is higher in the presence of unsteady flow. Moreover, with Jinping-I hydropower station as an ex- ample, we calculated the permeability coefficient respectively in steady flow and unsteady flow conditions based on the measured water pressure test data of the grouting inspection drilling. The results demonstrate that the permeability coefficient in unsteady flow condition is less than that in steady flow condition in short duration water pressure test.