摘要: |
含水层的渗透系数,是基坑降水设计中重要的水文地质参数。不同计算方法计算同一土层的渗透系数其结果会产生差异,故选取最适合该土层的计算方法,避免产生较大误差,在设计计算中十分重要。本文基于砂卵石潜水含水层现场单井抽水试验结果,分别利用Dupuit-Kusargent法,Thiem法,直线斜率法以及水位恢复法四种方法来计算潜水含水层渗透系数,对比各计算结果与室内试验结果的差异,讨论了造成这种差异的原因,指出了各种方法的优缺点和适用性。研究结果表明,Dupuit-Kusargent法误差最大,直线斜率法次之,水位恢复法和Thiem法误差较小。同时Dupuit-Kusargent法计算结果受流量影响较大,一致性较差,其他方法结果的一致性较好。在计算砂卵石含水层的渗透系数时,当地层且有两个以上观测井时,应优先选用Thiem法;无观测井的情况下选用水位恢复法;有一个观测井且其降深-时间对数关系直线段明显时可选用直线斜率法,Dupuit-Kusargent法因计算误差较大故不推荐使用。 |
关键词: 砂卵石 含水层 渗透系数 抽水试验 |
DOI: |
分类号:TU46 |
基金项目:自然科学基金面上项目(41977239) |
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Comparison of methods to calculate coefficient of permeability of sandy cobble aquifer based on pumping tests |
FAN Dandan1, QI Licheng2, CHEN Qun1
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1.State Key Laboratory of Hydraulics and Mountain River Engineering,College of Hydraulic and Hydroelectric Engineering,Sichuan University;2.China Railway Er yuan Engineering Group Co,Ltd
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Abstract: |
The coefficient of permeability of aquifer is an important hydrogeological parameter in foundation pit dewatering design. The calculated coefficient of permeability of the same soil layer by different calculation methods may be different, Thus it is very important to select the most suitable calculation method for a certain soil layer to avoid large errors. Based on the test results of single well pumping tests in sandy cobble ground, four common methods, i.e. Dupuit-Kusargent method, Thiem method, straight-line slope method and water level recovery method are used to calculate the coefficient of permeability of aquifer. The differences between the calculated and the indoor test results are compared, the reasons resulted in the differences are discussed, and the advantages, disadvantages and applicability of each method are pointed out. The analysis results show that the error of Dupuit-Kusargent method is the largest, that of the straight-line slope method is the second, and the error of water level recovery method and Thiem method is small. Furthermore, the results from Dupuit-Kusargent method are greatly affected by the pumping flow rate, its consistency is poor. The consistency of the results from other methods are good. For determination of the coefficient of permeability for sandy cobble aquifer, Thiem method should be preferred when there are more than two observation wells. The straight-line slope method can be used when there is an observation well, and the falling depth and the logarithm of time in good agreement with the linear relationship. The water level recovery method can be used when there is no observation well. It is not recommended to use Dupuit-Kusargent method due to its large error. |
Key words: sandy cobble aquifer permeability coefficient Pumping test |