Semi-analytical solution to pumping test data with barrier, wellbore storage, and partial penetration effects
| Autor: | Wen-Chieh Cheng, Takenori Hino, Jack Shuilong Shen, Yong-Xia Wu |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
geography
geography.geographical_feature_category Computer simulation 0208 environmental biotechnology 0211 other engineering and technologies Geology Aquifer 02 engineering and technology Penetration (firestop) Mechanics Stage ii Geotechnical Engineering and Engineering Geology 020801 environmental engineering Wellbore Geotechnical engineering Asymptote Stage iv 021101 geological & geomatics engineering Test data |
| Zdroj: | Engineering Geology. 226:44-51 |
| ISSN: | 0013-7952 |
| DOI: | 10.1016/j.enggeo.2017.05.011 |
| Popis: | There exist some difficulties in determining aquifer parameters based on pumping test data within a partially penetrated retaining walls using traditional Cooper-Jacob method. Many other site-specific factors, such as the effect of partially penetrating well and the large diameter of the wells, cannot easily be accommodated in theoretical well formulae. The semi-log drawdown-time curves affected by the effects of barrier, wellbore storage, and partial penetration well can be characterised by four distinct stages of drawdown: i) Stage I, drawdown is unaffected by the barrier, ii) Stage II, drawdown is significantly influenced by the barrier, iii) Stage III, the drawdown-time curve runs parallel to that deduced from greenfield conditions, and iv) Stage IV, the drawdown becomes a constant value. To handle the four distinct stages of drawdown, a semi-analytical method using the slope of the late-time drawdown asymptote of Stage III for determining the transmissivity is proposed. The horizontal intercept, resulting from an extension of the late-time drawdown asymptote from Stage II, is used for determining the storage coefficient. Pumping test data from a case history are analysed using the proposed semi-analytical method, and the results obtained are compared with those deduced from the numerical simulation. The comparison between the analytical results and those obtained from the numerical simulation appeared satisfactory. |
| Databáze: | OpenAIRE |
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