敞开型测压管水位监测的滞后时间问题研究

分析了敞开型测压管在水位监测时产生滞后现象的机理，提出了一种简单新方法估算滞后时间，并与Hvorslev解答进行了对比。参数分析结果表明，所提出方法估算的滞后时间约为Hvorslev解答的1/5～1/10。当测压管进水段的长度足够时，敞开型测压管可以应用于渗透系数为10-5甚至10-6 cm/s的土体当中，而不会产生显著的滞后现象。通过28根敞开型测压管的现场注水试验，检验了测压管的灵敏度，并验证了分析结果的合理性。

Study of time lag problem of piezometric level observations using open standpipes

The mechanisms of the time lag phenomenon induced in piezometric level observations using open standpipes are analyzed. A new simple method is proposed to estimate the lag time; and it is compared with the Hvorslev’s solution. It is found from parametric studies that the estimated lag time by the proposed method is about 1/5 to 1/10 of that by the Hvorslev’s method. When the length of the intake portion of the standpipe is long enough, the open standpipes can be used in a soil with the coefficient of permeability of 10-5 or even 10-6 cm/s, without inducing significant time lag phenomenon. The degrees of sensitivity of 28 open standpipes were examined by field rising-head tests; and the results from the proposed method are verified by the tested results.