Hydraulic conductivity of geosynthetic clay liners to tailings impoundment solutions

The results of a comprehensive testing program conducted to evaluate the hydraulic conductivity (k) of two geosynthetic clay liners (GCLs) considered as a liner component for a tailings impoundment at a proposed zinc and copper mine are reported. The two GCLs were permeated with a relatively low ionic-strength ground water (GW) from the mine site and two electrolyte solutions, a process water (PW) and a simulated leachate (SL), with chemical compositions consistent with those expected during operation of the impoundment. A total of 22 flexible-wall tests were performed to determine the effects of prehydration with the GW, type of GCL, type of permeant liquid, and duration of the back-pressure stage of the test. The k values for both GCLs permeated with the GW were 1.7 × 10⁻⁹ cm/s, which is within the range 1–3 × 10⁻⁹ cm/s typically reported for GCLs permeated with low ionic-strength liquids, such as deionized water. However, the mean values of k based on permeation of duplicate specimens of both types of GCL with either PW or SL relative to the values of k based on permeation with GW, or k/k_w, ranged from a factor of 200 (2.3 orders of magnitude) to a factor of 7600 (3.9 orders of magnitude). Thus, both tailings impoundment solutions had significant adverse impacts on the hydraulic performance of both GCLs. Given the overall range of k/k_w values, factors such as prehydration, type of GCL, type of permeant liquid, and duration of back pressure, were relatively insignificant. The results of this study serve to emphasize the need to perform hydraulic conductivity testing using site specific materials.     

恰甫其海粘土心墙坝施工期及蓄水初期监测资料分析

阐述了新疆恰甫其海水库粘土心墙坝在施工期和蓄水初期，粘土心墙和坝壳料的沉降变形规律及特征值，对心墙和坝壳料的施工质量进行了初步评价。分析了坝体、坝基、坝肩蓄水前后的渗流变化情况，对粘土心墙的工况和帷幕阻水效果进行了初步评价，并对心墙蓄水前后的土压力进行了定性分析。     

Effects of river regulation on water quality in the lower Mokelumne River,California

This study examines the effects of flow regulation on water quantity and quality by comparing an impounded system (Mokelumne River) with an adjacent unimpounded system (Cosumnes River). Between 1999 and 2002, the Cosumnes River displayed a strong seasonal cycle for each constituent analysed (total suspended solids, NO₃‐N, total nitrogen, PO₄‐P, total phosphorus, dissolved silicon, specific conductivity, flow), while reservoirs in the lower Mokelumne buffered and attenuated physical and chemical fluctuations creating a weak seasonal pattern. Dissolved silicon and total suspended solids were the two constituents most efficiently sequestered by the reservoirs. While the reservoirs acted as traps for most constituents, NO₃‐N and PO₄‐P were produced during the drier years of the study, 2001 and 2002. In contrast, the unimpounded reference reach in the Cosumnes was an annual source for all constituents measured. The Cosumnes delivers its highest NO₃‐N concentrations during the winter months (December–April), while peak concentrations in the Mokelumne occur during the snowmelt (May–July) and baseflow (August–November) seasons. Due to downstream N‐limitation, this temporal shift in NO₃‐N export may be contributing to accelerated algal growth in the reach immediately downstream and eventually to algal biomass loading to the downstream Sacramento–San Joaquin Delta. Copyright © 2005 John Wiley & Sons, Ltd.     

旺村电站正常蓄水后对京南电站影响预测

分析和预测京南电站在旺村电站蓄水后由于尾水位的提高,对发电运行及水工建筑、金结设备的检修维护产生的影响.     

非饱和非稳定渗流作用下边坡稳定的有限元塑性极限分析下限法

常规的土坡稳定性分析方法主要是基于饱和土理论和稳定渗流情况,难以反映降雨作用和水位骤降对边坡稳定的影响,而实际上相当一部分坡体失稳是由于非饱和非稳定渗流引起的。基于Bishop提出的非饱和土有效应力原理以及Fredlund双应力强度理论,将任意时刻的水压力当做体积力考虑到平衡方程中,用基于有效应力的方式建立满足平衡条件、间断条件、应力边界条件以及屈服条件下考虑非饱和非稳定渗流作用的下限法非线性规划模型,并且编制了相应的程序。通过对降雨入渗和库水骤降的边坡数值算例的分析,验证了所提方法的正确性,对非饱和非稳定渗流作用下土坡失稳的规律有了进一步的认识。     

Size‐Dependent Staging and Phase Transition in LiFePO4/FePO4

The LiFePO₄/FePO₄ phase transition process is remarkable in terms of its excellent reversibility, making this redox system extremely promising for high rate lithium storage. The recent observation of ordering effects (Li_0.5FePO₄) during the phase transition challenges the traditional two phase models. In this work, the phenomenon of staging for LiFePO₄ for different sizes (70 nm and 50 nm) by high resolution aberration corrected annular bright electron microscopy is detected, investigated, and discussed along with previous results on larger crystals. In the small crystals, staging is found throughout with a decrease of order from center to the surface. For the larger crystal, a staging phase occurs constituting the interfacial zone (width around 15 nm) between LiFePO₄ and FePO₄. A comparison is made to recent experiments on even larger crystals showing such an interphase of smaller extent (around 2 nm). Thus it appears that these zones narrow with increasing size. These findings are discussed in the light of phase transition thermodynamics and kinetics. In particular, the possibility is discussed that the staging interphase may constitute a low energy solution to the LiFePO₄/FePO₄ contact.     

雨水集蓄利用解决缺水山区人畜饮水的探讨

阐述了凤冈县常用集流面种类及各自的特点,以及一户四口之家雨水集蓄利用的蓄水工程容积、集流面积的计算方法。     

Metabolic assessement of spleen infiltration by non-Hodgkin lymphoma using ^18F-FDG PET/CT： Preliminary clinical results

infiltration without morphology changes, which may not be diagnosed exactly by conventional image.     

The potential role of tributaries as seed sources to an impoundment in Northern Sweden: a field experiment with seed mimics

Fragmentation and flow regulation of rivers by large dams are known to obstruct the longitudinal dispersal of waterborne plant propagules between impoundments, and to affect plant community composition. However, even several decades after a dam has been built, impoundments may still have a relatively species‐rich riparian flora. We hypothesized that free‐flowing tributaries act as the major gene pools for such impoundments, thus alleviating the fragmenting effect large dams have on the main channel. The importance of tributaries as seed sources was tested by releasing wooden seed mimics in three different‐sized (0.22–6.93 m³ s^?1) tributaries of an impoundment in the Ume River in Northern Sweden. In each tributary seed mimics were released, during the spring flood peak, from three points approximately 1, 2 and 3 km upstream the outlet in the impoundment. The importance of a tributary as a seed source increased with tributary size. Of the 9000 released seed mimics 1.5% reached the impoundment; 1.2% of the 9000 originated from the largest tributary and 0.3% from the middle‐sized one. The smallest tributary retained all its mimics. Copyright © 2007 John Wiley & Sons, Ltd.     

小浪底水库拦沙初期泥沙输移及河床变形研究

应用物理模型试验对小浪底水库运行初期的泥沙输移和河床变形进行了一系列的研究预测,结果表明水库运用初期基本上为异重流排沙;库区干流淤积形态为三角洲且不断向下游推进;支流淤积主要是干流倒灌的结果,在沟口可形成拦门沙;库水位大幅下降,干流河床将产生溯源冲刷和沿程冲刷,支流淤积面随之下降。水库投入运用以来的实测资料分析表明,尽管预报试验所采用的水沙条件与水库运用以来的实际情况不尽相同,但两者在输沙流态、淤积形态及变化趋势方面基本一致,从而证明了模型试验得出的结论是符合实际的。