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弱透水层是含水层系统的重要组成部分。弱透水层的渗透系数K_v和弹性贮水率值S_(ske)对研究地面沉降及地下水资源评价具有重要的意义。在相邻含水层降深随时间周期性波动的条件下,推得了超固结弱透水层中无量纲形式的降深解析解,并基于该解析解进一步得到了超固结弱透水层累计变形量随时间变化的理论曲线。由于弱透水层的低渗透性,其变形总是滞后于相邻含水层的降深变化。根据弱透水层变形的滞后时间与含水层降深波动半周期的关系,提出了一种用以确定超固结弱透水层垂向渗透系数和弹性贮水率的方法,该方法对于弹性变形的超固结土具有很好的适用性。使用该方法之前,首先要根据分层标和水位资料确定含水层降深的变化周期以及弱透水层变形的滞后时间。应用该方法确定了上海地区f_(10-7)分层标处第2弱透水层的水力参数为K_v=4.12×10~(-10)m/s,S_(ske)=1.07×10~(-4) m~(-1)。经实例计算结果具有一定的可靠性。
The aquitard is an important part of the aquifer system. The permeability coefficient K_v of the aquitard and the skewness of the elastic water storage rate are of great significance for studying the land subsidence and the evaluation of groundwater resources. Under the condition that the depth of the adjacent aquifer periodically fluctuates with time, the dimensionless form of the analytic solution in the overconsolidated aquitard is extrapolated, and the cumulative deformation of the overconsolidated aquitard is further obtained based on the analytic solution The amount of change over time theoretical curve. Due to the low permeability of the aquitard, its deformation always lags behind that of the adjacent aquifer. According to the relationship between the lag time of the deformation of the aquitard and the half-period of the descending aqueduct, a method to determine the vertical permeability coefficient and the elastic water storage rate of the overconsolidated aquitard is proposed. Overconsolidated soil has good applicability. Before using this method, we must first determine the variation period of the aquifer degradation and the lag time of the deformation of the aquitard based on the stratification and water level data. The hydraulic parameters of the second aquitard at f_ (10-7) in Shanghai are K_v = 4.12 × 10 ~ (-10) m / s and S skew = 1.07 × 10 ~ -4) m ~ (-1). The result of example calculation has certain reliability.