综合利用多种方法确定潜水含水层渗透系数

为确定潜水含水层的渗透系数,施工了一个主抽水井和两个观测井,采用了潜水含水层稳定流完整井多孔、单孔抽水试验的公式法、非稳定流的完整井的半对数直线图解法和基于抽水试验资料处理软件的纽曼模型求参法三种方法进行计算,结果发现各计算方法的结果相差不大,能够相互验证。最后,选取半对数直线图解法的计算结果作为最终计算结果。该研究对潜水含水层渗透系数的计算有一定的参考价值。     

Interpretation of pumping test data from large diameter wells on an oceanic island

 Estimation of aquifer parameters is vital for the assessment of groundwater potential and groundwater flow regime. On an oceanic island where fresh water lens is fragile and sensitive to various stresses, it is even more essential that in order to assess the potential of fresh water lens and the effect of various stresses on the fresh groundwater regime the parameters should be representative to the field hydrogeological set up. Pumping tests conducted on existing large diameter wells on an oceanic island have been analyzed. A finite difference method has been used to take into account the well storage, partial penetration and upconing effect into the aquifer. Forward modeling has been carried out to estimate aquifer parameters from the pumping test data. Field examples are described. Received: 15 June 1998 · Accepted: 25 August 1998     

抽水组数和先验信息对估算三维非均质含水层渗透系数的影响

水力层析抽水实验可以高精度刻画非均质含水层渗透系数分布,但野外成本高,需要对抽水试验进行优化.通过构建三维非均质含水层砂箱,开展水力层析抽水实验,探讨不同抽水组数和先验信息对刻画渗透系数的影响.分别利用不同抽水组数和融入42个井段岩心渗透系数作为先验信息,对渗透系数场进行估算,并用以预测独立抽水实验过程,对比估算结果优...     

What can be learned from sequential multi-well pumping tests in fracture-karst media? A case study in Zhangji, China

A fracture-karst aquifer is a karst aquifer with a fractured rock matrix, and its parameters are difficult to determine. Two sequential pumping tests in a fracture-karst aquifer system at the Zhangji well field of China are considered, one carried out before (in 2000) and one after (in 2005) the operation of a pumping station in the well field (2003–2005). The sequential tests serve multiple purposes. First, they provide a cross check of the parameters obtained. Second, they can be used to assess the effect of long-term groundwater exploitation of the aquifer. A three-dimensional finite-element transient flow model has been developed to simulate groundwater flow at the site. Generally good agreement has been found between the simulated and observed hydraulic heads for both tests. The hydraulic parameters obtained from the 2005 test are generally consistent with their counterparts from the 2000 test. However, a small but steady increase of hydraulic conductivities from 2000 to 2005 at the site has been observed. A 10-year prediction of groundwater resources has been made and indicates that the well field can accommodate the proposed 8.0?×?10⁴ m³/day exploitation rate under relative drought conditions without causing a steady decline of groundwater levels.     

苍峄铁矿带苍山县沟西西官庄矿区沟西矿段（凤凰山铁矿）主井井筒检查孔水文地质特征分析

苍峄铁矿带苍山县沟西西官庄矿区沟西矿段,又称凤凰山铁矿,为隐伏的鞍山式低品位铁矿,矿区水文地质条件属于中等型。对施工的主井、副井、进风井、东风井和西风井井筒检查孔进行了水文地质编录和分层抽水试验,以主井井筒检查孔为例,划分了4层含水段,求得了各含水层的水文地质参数,对荒径涌水量进行了预测;基本查明了井筒检查孔的含水性等水文地质特征,确定了注浆段,为矿山立井防治水方案提供了设计依据。     

水力层析法与克立金法估算非均质含水层渗透系数场比较

含水层非均质性空间分布特征的识别,是准确模拟地下水流和污染物运移的前提.基于室内非均质含水层砂箱实验,分别利用水力层析法和克立金插值法刻画了非均质含水层渗透系数场.研究结果表明:(1) 水力层析法与克立金法相比,不仅可以更好地刻画非均质含水层渗透系数场,还可以更高精度地预测地下水流过程;(2) 水力层析抽水实验中,通过增加抽水实验组数可以有效地提高水力层析参数反演的精度,但是抽水实验组数增加到一定程度以后,再增加抽水组数不会显著提升参数反演的效果.后续需要进一步研究水力层析抽水实验合适的组数,进一步对抽水井进行优化布设.      

Determination of groundwater solute transport parameters in finite element modelling using tracer injection and withdrawal testing data

The groundwater tracer injection and withdrawal tests are often carried out for the determination of aquifer solute transport parameters. However, the parameter analyses encounter a great difficulty due to the radial flow nature and the variability of the temporal boundary conditions. An adaptive methodology for the determination of groundwater solute transport parameters using tracer injection and withdrawal test data had been developed and illustrated through an actual case. The methodology includes the treatment of the tracer boundary condition at the tracer injection well, the normalization of tracer concentration, the groundwater solute transport finite element modelling and the method of least squares to optimize the parameters. An application of this methodology was carried out in a field test in the South of Hanoi city. The tested aquifer is Pleistocene aquifer, which is a main aquifer and has been providing domestic water supply to the city since the French time. Effective porosity of 0.31, longitudinal dispersivity of 2.2 m, and hydrodynamic dispersion coefficients from D = 220 m²/d right outside the pumping well screen to D =15.8 m²/d right outside the tracer injection well screen have been obtained for the aquifer at the test site. The minimal sum of squares of the differences between the observed and model normalized tracer concentration is 0.00119, which is corresponding to the average absolute difference between observed and model normalized concentrations of 0.035 5 (while 1 is the worst and 0 is the best fit).     

Re-evaluating the US Geological Survey’s pumping tests (1967) in the Punjab region of Pakistan for use in groundwater studies

In 1967, the US Geological Survey (USGS) published the results of 141 pumping tests carried out throughout the Pakistani Punjab to establish representative hydraulic parameters of its large aquifer. Many authors have since concluded that the USGS had over-estimated the horizontal hydraulic conductivity (k _r) by 25–100 %, leaving vertical anisotropy and aquifer depth unresolved. No test wells have ever been drilled below 450 m to reach the base of the aquifer, although petroleum explorations mention depths between 1,500 and 4,500 m. After comparison and re-evaluation of all related papers, this study concludes that the USGS interpretation was correct, that its hydraulic values still stand without change, and that the USGS’s applied distance drawdown interpretation is valid to prevent influence of partial penetration on the results. This study also uniquely resolved vertical anisotropy and aquifer thickness by using early- and late-time drawdowns separately and proper scaling of the coordinates, which has often been omitted. With appropriate scaling, all interpretations match the data. The representative hydraulic aquifer values are: k _r?=?65 m/d, vertical anisotropy k _r/k _z?=?25 and aquifer depth 500–1,500 m. The conclusion is that these values can be used, at least as first estimates, for groundwater studies in the Pakistani Punjab.     

可地浸砂岩型铀矿床抽水试验方法对比及有关问题探讨

本文对新疆伊犁盆地库捷尔太铀矿床抽水试验及参数计算方法做了较为详细的对比分析，总结出适合于可地浸砂岩型铀矿床不同工作阶段求取 含水层渗透系数的抽水试验方法；阐述了在自喷井中用扬水试验求取含水层渗透系数方法的可行性及其在实际应用时应注意的问题；提出利用数量固定不可调的深井泵进行变流量抽水以控制不同的降深，解决了多年来因空气压缩机性能所限难以进行长时间抽水的问题，并对抽水试验的延续时间、降深次数以及降深等参数提出了具体建议。     

Evaluation of methods for determination of hydraulic properties in an aquifer–aquitard system hydrologically connected to a river

Field and laboratory methods have been used to determine the hydraulic properties in a multiple-layer aquifer–aquitard system that is hydrologically connected to a river. First, hypothetical pumping tests in aquifer–aquitard systems were performed to evaluate the feasibility of MODFLOW-PEST in determining these parameters. Sensitivity analyses showed that: the horizontal hydraulic conductivity in the aquifer has the highest composite sensitivity; the vertical hydraulic conductivity has higher composite sensitivity than the horizontal hydraulic conductivity in the aquitard; and a partial penetration pumping well in an aquifer layer can improve the quality of the estimated parameters. This inverse approach was then used to analyze a pumping-recovery test conducted near the Platte River in southeastern Nebraska, USA. The hydraulic conductivities and specific yield were calculated for the aquitard and aquifer. The direct-push technique was used to generate sediment columns; permeameter tests on these columns produced the vertical hydraulic conductivities that are compatible with those obtained from the pumping-recovery test. Thus, the combination of the direct-push technique with permeameter tests provides a new method for estimation of vertical hydraulic conductivity. The hydraulic conductivity, determined from grain-size analysis, is smaller than the horizontal one but larger than the vertical one determined by the pumping-recovery test.     

Numerical study of dewatering in a large deep foundation pit

During foundation pit excavation, groundwater is often the most important factor that affects pit stability. Dewatering is widely used in pit excavation to avoid uplift of excavation floors due to high water pressure. The characteristics of seepage in small-scale deep foundation pits of high-rise buildings or in the long narrow foundation pits of subway stations have been extensively investigated. However, the characteristics of seepage in large-scale deep excavations have not been studied. This paper investigates the large deep excavation of the buildings in Oriental Fisherman’s Wharf. The total area of the construction site is 33,917 m². Single-well and group-well field pumping tests were performed and a numerical simulation by 3D finite difference method (FDM) was carried out. The simulation used results from the field pumping tests. The permeability parameters of the confined aquifer were then revised, based upon comparisons of simulation and observation results. Subsequently, dewatering schemes were simulated by FDM forward analysis. The simulation results show that dewatering schemes can minimize seepage and uplift in large excavation pits, though settlement outside the pit may need treatment measures.     

用水化学方法确定岩溶富水区——以山西延河泉域为例

利用延河泉域含水层的水质分析资料,计算地下水中侵蚀性CO2的含量、矿物饱和指数（βi）与奥陶系灰岩（O2）顶面标高（H）的函数关系。通过作图与分析其关系曲线,对延河泉域含水层进行富水性分区,得到奥陶系顶面标高在350～600m间为强富水区．q=5．55～6．975L（s．m）;标高在750-600m及350-200m间为中强富水区;标高存700m以上和600m以下为弱富水区,该结论经过勘探和抽水试验得到了验证。     

Multi-aquifer pumping test to determine cutoff wall length for groundwater flow control during site excavation in Tokyo, Japan

Multi-aquifer pumping tests, using a multi-screen pumping well and multi-level piezometers, were carried out for groundwater flow control in a large-scale excavation site in Tokyo, Japan. The site was underlain by multi-layered confined aquifers. In the tests, pumping was carried out using a multi-aquifer pumping well in which a screen depth was chosen arbitrarily. Changes in groundwater pressure heads in each aquifer were measured at each screen position of the multi-aquifer pumping well. Hydraulic conductivity (K) and specific storage (S _s) of not only aquifers, but also for low permeability layers between the aquifers, were estimated using the Cooper-Jacob method, and calibrated by a finite element method (FEM) groundwater model. Four different cutoff wall lengths were assumed for final excavation depth, and correlations among wall length, pumping discharge and drawdown at the back of the cutoff wall were obtained from simulations using the K and S _s parameters in the FEM model. Then, the most suitable wall length was selected based on the simulated correlations considering environmental condition, construction period and cost of the cutoff wall.     

基于解析法和数值法的非稳定流抽水试验参数反演

含水层的水文地质参数是进行地下水资源计算、地下水污染防控等所必需的基础数据,结合数值模拟技术进行含水层参数反演很有必要.按照1:5万水文地质调查规范在江汉平原仙桃市杨林尾镇复兴水厂不同含水层位开展抽水试验,包括深层含水层单孔抽水试验以及浅层含水层中群孔(2孔)抽水试验.对于单孔抽水试验,应用第1类越流系统井流理论进行参数反演;对于群孔抽水试验,推导了特定综合井函数,并利用特定标准曲线匹配法和直线图解法求解了含水层参数.随后利用FEFLOW软件建立了相应数值模型,拟合了含水层参数.结果表明:浅层含水层的渗透系数变化范围为21.66~54.00 m/d,贮水率变化范围为1.28×10-5~8.00×10-4 m-1;深层含水层渗透系数变化范围为1.27~7.00 m/d,贮水率变化范围为3.90×10-6~5.00×10-6 m-1.对于深层承压含水层而言,越流补给量较大.采用数值模拟方法结合抽水试验数据求参,综合考虑了含水层结构,拟合效果好,所得结果更加可靠.      

多工艺联合洗井和抽水试验在CGSD-01井中的应用

天津东丽湖CGSD-01井为地热勘探井,设计井深4000 m,完钻井深4051.68 m。为最大程度清理钻井过程中对含水层的堵塞,本井采用了焦磷酸钠洗井、压缩空气洗井和酸化洗井3种工艺方法联合洗井,并先后进行2次抽水试验。联合抽水试验表明多工艺联合洗井效果理想。本文主要阐述了CGSD-01井洗井及抽水试验实施工艺,以期为今后同类研究及施工提供有益的借鉴。     

Estimating aquifer thickness using multiple pumping tests

A method to estimate aquifer thickness and hydraulic conductivity has been developed, consisting of multiple pumping tests. The method requires short-duration pumping cycles on an unconfined aquifer with significant seasonal water-table fluctuations. The interpretation of several pumping tests at a site in India under various initial conditions provides information on the change in hydrodynamic parameters in relation to the initial water-table level. The transmissivity linearly decreases compared with the initial water level, suggesting a homogeneous distribution of hydraulic conductivity with depth. The hydraulic conductivity is estimated from the slope of this linear relationship. The extrapolation of the relationship between transmissivity and water level provides an estimate of the aquifer thickness that is in good agreement with geophysical investigations. The hydraulically active part of the aquifer is located in both the shallow weathered and the underlying densely fractured zones of the crystalline basement. However, no significant relationship is found between the aquifer storage coefficient and initial water level. This new method contributes to filling the methodological gap between single pumping tests and hydraulic tomography, in providing information on the variation of the global transmissivity according to depth. It can be applied to any unconfined aquifer experiencing large seasonal water-table fluctuations and short pumping cycles.     

Study on the hydraulic parameter differences between pumping and recharge in a confined aquifer of a soft soil area

Artificial recharge is an effective remediation measure for controlling groundwater level and subsidence in many coastal cities in China. Hydraulic parameters estimated by pumping tests are often used in the design of both pumping and recharge systems. However, the hydraulic parameters in the recharge process have been found to differ from those in the pumping process and should be studied in greater detail. Eight single-well pumping and recharge tests were conducted within a confined aquifer in a soft soil area in the city of Tianjin, and the differences in wellbore storage influences and well losses between the recharge and pumping processes were examined. Furthermore, based on the Hantush and Jacob model, an algorithm combining the Levenberg–Marquardt algorithm (LMA) and genetic algorithm (GA) was employed for estimation of the hydraulic parameters. The results illustrated that the combined algorithm eliminating wellbore storage influences could provide hydraulic parameters from which the groundwater level variation could be accurately simulated. The hydraulic conductivity and specific storage values obtained in the pumping tests were higher than those obtained in the recharge tests. In addition to slight plugging of the recharge well, the specific storage differences could be explained by the compression and rebound deformation characteristics of sand in the confined aquifer. The specific storage estimated by pumping tests should be adjusted when applied in groundwater recharge calculation.

     

Characteristics of Valadares Island aquifer,Paranaguá coastal plain,Brazil

. Aquifer characterization in terms of geologic–geomorphological considerations, pumping test and hydrochemistry has been carried out to evaluate the groundwater potential of one of the delicate coastal island systems in Parana State, Brazil. The Valadares Island, lying in the Atlantic coastal zone, represents a stabilized beach ridge having a thickness of more than 20 m unconsolidated quartz-rich sand. Field and laboratory investigations suggest that this homogeneous coastal aquifer can partially meet the local domestic demand of fresh water even though it is in hydraulic continuity with the estuarine and tidal systems of Paranaguá bay. Efficiency of the aquifer to hold and release water was determined by conducting a pumping test in one of the partially penetrating wells in the island for 24 h. The physical, chemical and biological analyses of samples from 12 5-cm diameter wells of the area have indicated that groundwater needs purification for drinking purpose. It is advocated that the groundwater potential of the island aquifer is worth considering for sustained but controlled exploitation.     

郭屯矿井井筒基岩富水性分析

根据山东郭屯矿建井前施工的井筒检查钻孔钻探取心、简易水文观测、地球物理测井（包括流量测井）及结合郭屯矿井精查地质报告资料,对井筒的含、隔水层进行了划分;通过抽水试验、流量测井方法求解了风氧化带含水层、风氧化带下含水层及其各含水层分层的水文地质参数,分别预算了主井、副井、风井井筒的涌水量,并分析了郭屯矿各井筒基岩涌水量大于邻近煤矿井筒基岩涌水量的主要影响因素。