基于微水试验倾斜承压含水层水文地质参数的推估

Hydrogeological Parameter Estimations for Slug Test in Sloping Confined Aquifer

为了准确的推估出倾斜承压含水层的水文地质参数,有必要考虑倾角对于参数推估的影响.通过建立倾斜承压含水层微水试验的数学模型,利用理论和现场试验数据分析方法,得出倾角对导水系数等水文地质参数推估的影响.结果表明:低渗透条件下,倾角越大非振荡水位恢复速度越快;高渗透条件下,倾角越大振荡水位振幅越大.储水系数越大倾角上限越小,倾角影响越明显,而倾角上限对于导水系数的变化不敏感.根据该结论建立了无因次储水系数和倾角界限之间的经验方程,用于预测倾角是否会影响水文地质参数的推估.当实测倾角大于倾角上限时,倾角影响不可以被忽略,忽略倾角会导致导水系数估值偏高,储水系数估值偏低.

It is necessary to take into account the dip angle effects on accurate estimation of hydrogeological parameters in the sloping confined aquifer. To explore how the dip angle influences the test response, a new slug test model is developed in this study by using theoretical and filed data analysis. For test well, it is found that when the aquifer hydraulic conductivity is rela- tively low, a larger dip angle causes a faster recovery of the non-oscillatory test response; when the aquifer hydraulic conductiv- ity is relatively high, a larger dip angle causes an increase of amplitude of the oscillatory test response. The dip angle effect is more pronounced for a larger storage coefficient, being less sensitive to the change of transmissivity. An empirical relationship is developed for the limiting dip angle as a function of the dimensionless storage coefficient. The function can be used to predict whether the estimate of hydrogeological parameters would be influenced by the dip angle. The effect can be neglected if the dip angle is less than the upper limit. However, it cannot be neglected if the dip angle is larger than the upper limit, otherwise, it can result in an overestimate of transmissivity and an underestimate of the storage coefficient.