气压作用下,井-含水层系统中地下水流是一类流体力学问题。本文应用井壁水流通量边界条件和气压作用下井壁内外水(孔)压平衡条件,提出了一个井水位随气压变化的解析公式。解析式表明,气压系数随时段长度增加而增大,并趋于气压常数;气压系数随时段长度的变化只依赖于导水系数与井半径平方的比值(T/r2w),而与气压变化过程无关;气压常数只与含水层的一维荷载效率(B)有关,而与导水系数和井半径无关。解析解所反映的气压系数与时段长度的关系,与南溪井实测序列数据分析结果具有很好的一致性。根据气压系数随时段长度变化过程,提出了一个参数估计方法,应用于估计南溪井含水层气压常数和导水系数,并对本文提出的参数估计方法进行了讨论。
Under barometric pressure(BP),groundwater flow in a well-aquifer system is a kind of hydromechanical coupling problem.Applying the flux boundary condition on borehole wall and water pressure equilibrium condition inside and outside the borehole wall under barometric pressure,an analytic solution to well water level changes is proposed in this paper.The formulation shows that the BP coefficients increase with time length and tend to BP constant.Change of BP coefficients over time length only depends on the ratio of transmissivity(T) to the well radius squared(r2w),and has nothing to do with the changing process of BP.The BP constant only relates to aquifer loading efficiency(B),and has nothing to do with the aquifer transmissivity and well radius.The BP coefficients change over time in the analytic formulation is consistent to the analysis conclusions of the measured data from Nanxi wells.Based on the BP coefficient changes over time length,a parameter estimation method has been suggested and discussed in its application to the estimation of aquifer BP constant(or B) and transmissivity using Nanxi well data.