深厚强透水含水层地铁深基坑地下水控制方案综合比选方法

针对深厚强透水含水层地铁深基坑地下水控制方案比选问题,联合运用层次分析法、模糊综合评价法以及数值计算方法,提出深厚强透水含水层地铁深基坑地下水控制方法定性与定量化比选流程框架,建立了强透水地层地铁深基坑地下水控制方案综合比选方法。以福州地铁水部站深基坑工程为例,采用建立的比选方法,对5种不同深基坑地下水控制方案（敞开式降水、落底式止水帷幕、深层水平封底帷幕、悬挂式止水帷幕降水以及水下开挖）进行定性评估分析,结果表明,悬挂式帷幕降水方案为该车站深基坑工程地下水控制最优方案。采用数值模拟方法,分析得到了深基坑降水引发的周边地表沉降值在12~23 mm之间,表明42 m悬挂式止水帷幕降水方案能有效控制深基坑降水引发的地表沉降。     

Methodologies for abstraction from coastal aquifers for supplying desalination plants in the south-east of Spain

Supplying seawater to desalination plants using boreholes or drains can be less expensive than direct water intakes, since the silt density index (SDI) tends to be much lower. This approach is dependent on the presence of coastal aquifers with good hydraulic connection to the sea. Moreover, conventional boreholes are not suitable for pumping water on a long-term basis, since seawater is very aggressive. Hence, this type of abstraction requires the application of special technologies, from borehole location to borehole lining and special operations. These include the selection of the most appropriate drilling method, which depends on the lithology to be penetrated and its structure. This study focuses on Horizontal Directional Drilling (HDD), which encompasses very advanced technology. Various examples of work done in south-eastern Spain are described, along with the keys to their success.     

Groundwater changes in the Wairakei–Tauhara geothermal system

Overlying most of the Wairakei–Tauhara geothermal system is a sequence of shallow aquifers. Some of these are groundwaters heated by fluids escaping from the deep geothermal reservoir, others are cold; some are extensive and confined, others are perched, unconfined and of limited extent. Water levels of some of the shallow aquifers have declined at various times throughout the history of geothermal development. One of the mechanisms causing the observed changes is an increase in groundwater downflow into depressurizing steam zones. This occurs through natural fractures that once channelled the ascent of two-phase fluids. Another important mechanism is internal downflow within boreholes connecting permeable aquifers that were otherwise hydrologically separated. These cool downflows have had a significant impact on the deeper reservoir, and also affect the discharge characteristics of surface thermal features. However, in the Southern Tauhara sector, outflows of dilute chloride fluid from shallow thermal aquifers have not been affected by the deep pressure drawdown. This could be attributed to liquid or two-phase upflow continuing to recharge the chloride component in the south, or to significant quantities of residual chloride in a large geothermally heated aquifer still masking recharge depletion that has occurred during the last 50 years.     

Fourier analysis of short-period water level variations in the Rotorua geothermal field, New Zealand

The results of a Fourier analysis of water level measurements recorded near the nationally significant Pohutu Geyser in New Zealand are reported. Their analysis clearly identifies periodic pressure variations induced by barometric, gravity, thermal, anthropogenic and subsurface disturbing influences, which can be used as a benchmark for identifying and quantifying detrimental changes in behaviour. A report is given on the performance of Fourier analysis on synthetically generated signals with different levels of white noise and discrete impulses. We were able to attribute periodic variations to various disturbing effects and quantify the magnitude of these changes. Diurnal and semi-diurnal variations for both anthropogenic and barometric disturbing influences are shown to have amplitudes in the range 2.8–5.2 mm-H₂O while earth tidal amplitudes are less than 1 mm-H₂O.     

Using linked process models to improve urban groundwater management: an example from Doncaster England

Linked water process models that simulate the complexities of urban water systems for towns overlying productive aquifers can help improve and better integrate urban water resource management. The Assessing and Improving the Sustainability of Urban Water Resources and Systems (AISUWRS) project has successfully linked together water scheduling, pipe leakage and groundwater flow models and applied these models to case studies in Europe and Australia. This paper describes the application and results of the modelling tools for a case study suburb in Doncaster England. The linking of process models offers the prospect of better quantification of flows and contaminant loads, and diverse scenarios were readily simulated once the base case had been set‐up. The linked models produced higher estimates of recharge than previous estimates, and this may suggest that suburban catchments are an underutilised resource. At a time when increasing urbanisation and rising water use is predicted for groundwater‐dependent southern England, there is a need for such tools to make the most of increasingly urbanised aquifers.     

Simulation of seawater intrusion in coastal aquifers: Some typical responses

Seawater intrusion in coastal aquifers is generally three dimensional (3-D) in nature. In the literature, there is a general lack of reported results on 3-D simulations. This paper presents some typical example simulations of 3-D seawater intrusion process for a specified hypothetical study area. The simulation results presented in this paper are based on the density-dependent miscible flow and transport modelling approach for simulation of seawater intrusion in coastal aquifers. A nonlinear optimization-based simulation methodology was used in this study. Various steady state simulations are performed for a specified study area. Response evaluations consider the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying pumping from the aquifer. The 3-D simulations demonstrate the viability of using a planned strategy of spatially varying withdrawals from the aquifer to manage seawater intrusion. It is demonstrated that series of pumps near the ocean-face boundary induce a hydraulic head distribution that can be effectively used for controlling seawater intrusion.     

工程地质模型在防水煤岩柱研究中的应用

提出了煤矿工程地质模型的概念和基本构成．论述了工程地质模型及其组成单元的采动效应,建立了预测模型并成功应用于山东省横河煤矿厚松散含水层下放顶煤开采防水煤岩柱的留设．为进一步发展防水煤岩柱工程地质系统研究方法奠定了基础．     

灰岩含水层的各向异性在矿山防治水中的应用

“双层水位流”在金岭铁矿的应用及谷家台矿区“坑内矿体顶板灰岩注浆堵水嗣后胶结充填”采矿方案的实施，说明有效利用中奥陶系灰岩含水层的各向异性，可以合理防治地下水，保护地下水资源和水文地质环境，并可节省投资。     

应用电阻率参数确定相邻含水层的连通性

本文介绍了确定相邻含水层连通性的一种方法和部分实验结果及应用成果。     

Comparison of Different Indicators for Groundwater Contamination by Seawater Intrusion on the Lebanese Coast

In order to evaluate the state of groundwater salination by seawater intrusion on the Lebanese coast, the region of Choueifat–Rmeyle, situated in the south of Mount-Lebanon, was chosen as a study zone. Overall, six wells were chosen and water sampling was done for three years starting from 1999 till 2002. Sampling was done on a monthly basis for ten months per year, from July till April. A complete physico-chemical analysis was done for all the water samples taken. Seawater intrusion in the Choueifat-Rmeyle region was studied through the interrelations between the chemical and physical constituents of groundwater. Results showed that the regions of Choueifat, Jiye and Rmeyle were subject to seawater intrusion. This intrusion was directly and simultaneously related to the pumping period and intensity but weakly linked to the quantity of rainfall. It was also related to the geologic nature of the study area. Furthermore, the actual intrusion in the study zone increases the already existing salinity problems. The salinity rates of wells water oscillated between 0.7 dS/m and 5.5 dS/m with the majority above 2 dS/m. This is leading to intolerable levels of water and soil salinity, inadequate for the cultivation of many crops, thus threatening their growth and production and reducing the agrodiversity in the region.