生活垃圾非饱和渗透性质测定的多步出流方法

传统土壤渗透性测量方法直接测量填埋生活垃圾的渗透性质误差较大.本实验现场测定六里屯填埋场原状垃圾土饱和含水率和饱和渗透系数,其平均含水率随填埋深度增加而增大,平均渗透系数为0.018 5mm·s^-1.在保证容重相同条件下,用多步出流法实验室测定扰动样品水分特征曲线和非饱和渗透系数.运用渗压出流和理论拟合测试技术,为建立渗透参数的随机分布模型提供参数测定方法.实验结果与模型显著相关.通过实验及模型模拟,揭示了填埋垃圾水分特征曲线的变化规律,证明多步出流法是适用于填埋场非饱和渗透性质测定的有效方法.     

湘江长沙综合枢纽蓄水初期长沙段水环境参数的变化

以湘江长沙段5个监测断面9个检测项目的实测数据为依据,运用综合指数法、污染物分担率以及营养状态综合指数法,分析了湘江长沙综合枢纽蓄水初期长沙段水环境参数的变化。结果表明:从总体上讲,长沙综合枢纽蓄水初期,长沙段5个监测断面水体的氨氮、高锰酸盐、总磷(营养物质)、挥发酚、石油类(有机毒物)镉、砷、汞、铅(重金属)9项综合污染指数等级、污染物分担率,以及营养物含量等级在时空尺度上均呈不同程度的下降趋势,其中以重金属污染指数下降趋势最明显。改善长沙段水环境质量的主要原因是:1长沙经济结构的优化与调整;2长沙综合枢纽建设与库区长沙段治污工程建设同步;3长沙综合枢纽蓄水功能,当水库蓄至正常水位时,一方面使库区长沙段年最低水位上升约1.5 m;另一方面使库区长沙、湘潭、株洲三江段分别较多年平均水位抬高4~6m、2~4m、1~2m,如此增加了长沙段水量,从而对水体污染物起到一定的稀释、降解与输移作用。     

水力停留时间对复合式厌氧折流板反应器乙醇型发酵制氢系统的影响

水力停留时间(HRT)是厌氧生物制氢工艺的重要工程参数.以红糖废水为底物,研究了HRT对复合式厌氧折流板反应器(HABR)作为乙醇型发酵制氢系统产氢效能的影响.结果表明,在设定的8~36 h范围内的5个HRT中,当HRT为12 h时,HABR制氢系统的效果最佳,产氢速率为13.86 mmol·(h·L)-1,COD去除率为51.51%,五格室的pH值在4.22~4.47之间,液相主要产物为乙醇和乙酸,第1~5格室乙醇和乙酸的比值分别为1.90、1.94、1.80、1.77、1.91,最佳能量生产为11.11 kJ·(h·L)-1.     

从河道自净角度谈影响河道水质净化的因素

摘要：在城市河道污染日趋严重的今天,利用河道水体自净过程的机理来解决河道水质污染问题正成为改善河道水质的一种趋势。通过对河道自净过程的分析,总结出溶解氧、水力条件、温度、微生物、河岸带在河水自净中起到了决定性的作用,并分别从上述五个方面来阐述它们在自净过程中发挥的重要性。这给改善河道水质提供了不少途径,目前许多的河道整治手段都是由此受到了启发。因此明确了在未来河流污染治理的道路上,从河道自净化规律出发去看待和治理河道水污染问题是非常必要的。     

曝气生物滤池处理性能影响因素实验研究

采用上向流曝气生物滤池处理生活污水,考察了气水比、水力负荷、有机负荷、滤料层高度等因素对曝气生物滤池处理性能的影响。结果表明,气水比为5：1时,COD和NH3-N的去除率分别为87．6％和60．1％;水力负荷在0．21—0．86m^3／（m^2·h）的条件下,COD的去除率随水力负荷的增加降幅较小,NH3-N的去除率下降明显;有机负荷在1．15～2．96kg／（m^3·d）的条件下,BAF表现出很好的抗有机负荷冲击能力。BAF对有机物的去除主要发生在滤料层0～70cm段,对NH3-N的硝化主要发生在滤料层40—100cm段。     

The impact of storm events on a riverbed system and its hydraulic conductivity at a site of induced infiltration

The spatial and temporal variability of riverbed vertical hydraulic conductivity (K(v)) was investigated at a site of induced infiltration, associated with a municipal well field, to assess the impact of high-stage events on scour and subsequently the riverbed K(v). Such impacts are important when considering the potential loss of riverbank filtration capacity due to storm events. The study site, in and along the Great Miami River in southwest Ohio, overlaid a highly productive glacial-outwash aquifer. A three-layer model for this system was conceptualized: a top layer of transient sediment, a second layer comprising large sediment resistant to scour, but clogged with finer sediment (the armor/colmation layer), and a third layer that was transitional to the underlying higher-K(v) aquifer. One location was studied in detail to confirm and quantify the conceptual model. Methods included seepage meters, heat-flow modeling, grain-size analyses, laboratory permeameter tests, slug tests and the use of scour chains and pressure-load cells to directly measure the amount of sediment scour and re-deposition. Seepage meter measured riverbed K(v) ranged from 0.017 to 1.7 m/d with a geometric mean of 0.19 m/d. Heat-transport model-calibrated estimates were even lower, ranging from 0.0061 to 0.046 m/d with a mean of 0.017 m/d. The relatively low K(v) was indicative of the clogged armor layer. In contrast, slug tests in the underlying riverbed sediment yielded K(v) values an order of magnitude greater. There was a linear relationship between scour chain measured scour and event intensity with a maximum scour of only 0.098 m. Load-cell pressure sensor data over a 7-month period indicated a total sediment-height fluctuation of 0.42 m and a maximum storm-event scour of 0.28 m. Scour data indicated that the assumed armor/colmation layer almost always remained intact. Based on measured layer conductivities and thicknesses, the overall K(v) of this conceptualized system was 1.6 m/d. Sensitivity analyses indicated that even complete scour of the armor/colmation layer would likely increase the overall K(v) only by a factor of 1.5. Most scour events observed removed only the transient sediment, having very little effect on the entire system indicating low risk of losing filtration capacity during storms. The research, however, focused on the point bar, depositional side of the river. More research of the entire river profile is necessary.     

Bayesian Nonstationary Frequency Analysis of Hydrological Variables1

Ouarda, T.B.M.J. and S. El‐Adlouni, 2011. Bayesian Nonstationary Frequency Analysis of Hydrological Variables. Journal of the American Water Resources Association (JAWRA) 47(3):496‐505. DOI: 10.1111/j.1752‐1688.2011.00544.x Abstract: The present paper provides a discussion of nonstationary frequency analysis models in hydrology with a focus on the Bayesian approach. The Bayesian model provides an efficient estimation framework of hydrological quantiles in the presence of nonstationarity. In nonstationary frequency analysis models, the parameters are functions of covariates, allowing for dependent parameters and trends. The use of the nonstationary Generalized Maximum Likelihood Estimation method in hydrologic frequency analysis is discussed. This model allows using prior information concerning the variables under study and considering a number of models (linear, quadratic, etc.) of the dependence of the parameters on covariates. A discussion is also provided concerning the use of the reversible jump Monte Carlo Markov Chain procedure which allows carrying out the estimation of the posterior distributions of the parameters and the selection of the Bayesian model at the same time. An application to a case study is presented to illustrate the potential of the model.     

定向水力压裂裂隙扩展动态特征分析及其应用

为减少煤矿井下水力压裂卸压盲区,扩大压裂影响范围,提高卸压增透效果,在分析水力压裂起裂机理和裂隙发展特征的基础上,提出定向水力压裂技术,分析定向水力压裂过程中煤体的裂隙发展分布规律,并利用RFPA2D-Flow软件模拟了压裂的起裂、扩展和延伸过程,对定向压裂与非定向压裂的效果进行了比较。最后将定向水力压裂技术在平煤集团十二矿己15-31010工作面进行了现场应用,得出在27 MPa的水压下,单孔压裂有效影响半径达6 m;单孔瓦斯抽放平均浓度较未压裂时提高80%,平均流量上升了382%,取得了显著的效果,具有良好的推广应用价值。     

基于贝叶斯网络的汽车起重机液压系统的可靠性评估

为评估汽车起重机液压系统的可靠性,首先结合故障树分析法(FTA)、贝叶斯网络(BN)构建液压系统故障树,然后映射成BN,再利用其在多态性和不确定性方面的优势,应用桶排除法,对系统进行可靠性评估。在给出底事件的发生概率后,通过正向推理,得到顶事件发生的概率为0.191 016。针对模型进行多态性和不确定性修正后,得到的顶事件概率为0.228 073,相对提高19.4%。最后利用反向推理,找出系统的薄弱环节并给出改正措施,为更全面高效的可靠性评估提出一种新方法。