Mapping Subsurface Seepage Flow Patterns in Proximity to a Coal Combustion Residual Landfill Using Electrical Resistivity Tomography

Electrical resistivity tomography data were acquired in proximity to the coal combustion residual landfill in an effort to image and analyze seepage pathways through the shallow residual soil and underlying karsted limestone bedrock. The water table is at a depth of more than 45 m. The most prominent subsurface seepage pathways identified on the acquired electrical resistivity tomography data are located immediately adjacent to the toe of the landfill and are attributed to stormwater run-off. The moisture content of the limestone appears to decrease gradually with increasing distance from the toe of the landfill, suggesting there is also a horizontal component of moisture flow in the subsurface. Shallow limestone with higher moisture content generally underlies or is in close proximity to anthropogenic features such as drainage ditches and clay berms that are designed to channel run-off. At one location, electrical resistivity tomography data were acquired along essentially the same traverse at different times of the year, and the resistivity of shallow limestone overall was lower on the data acquired after heavy rains.

Occurrence and Evaluation of Chromium Reducing Bacteria in Seepage Water from Chromite Mine Quarries of Orissa, India

Chromium pollution due to leaching and weathering of chromite mine overburden in mine seepage water is a serious environmental problem. In an attempt to explore the indigenous chromate resistant and reducing bacteria from chromite mine quarry seepage, 145 aerobic, heterotrophic bacteria were isolated from 14 mine seepage samples derived from chromite mines of Sukinda valley and Baula-Nuasahi belt in Orissa, India. A total of 109 isolates which were tolerant to 2 mM Cr(VI) showed different degrees of Cr(VI) reducing activ-ity in complex KSC medium and synthetic Vogel Bonner (VB) broth. Ten isolates belonging to genera like Pseudomonas, Acinetobacter, Alcaligenes, Cupriavidus and Corynebacterium were selected on the basis of their chromate reducing efficiency and it was found that they could reduce more than 50 and 75% of Cr(VI) in VB broth and KSC medium respectively. The sole Gram-positive isolate, Corynebacterium paurometabo-lum SKPD 1204 (MTCC 8730) showed maximum chromate reducing capacity in both VB broth (63.7%) and KSC medium (92%) and was capable of reducing nearly 95% of the total Cr(VI) in the mine seepage when it was grown in the mine seepage supplemented with 2% VB concentrate.

Seepage behavior of soil mixed with randomly distributed recycled plastic materials

Seepage through embankment fill materials is crucial issue in the construction of embankments for irrigation and drainage projects.Proper ground improvement methods should be used to improve the strength and stability characteristics of soil used as fill material.Utilization of waste plastic materials to enhance the engineering properties of soil is a sustainable approach.Additionally,the use of raw products directly from plastic recycling units in the form of flakes and pellets as soil additives has the potential to further enhance the economic benefits of this method.This study randomly mixed plastic materials with soil for use in the construction of earth embankments,such as river levees,dykes,and canal diversion structures,and evaluated the effectiveness of these materials in reducing seepage failures in hydraulic structures.To achieve these goals,this study collected high-density polyethylene(HDPE)plastic from plastic recycling units and used soil mixed with HDPE plastic in the form of flakes and pellets in different contents as embankment fill materials,then evaluated how these materials affected the piping features.Laboratory experiments were conducted to determine the seepage velocity and critical hydraulic gradient of soil mixed with plastics in various contents and to compare the values with those of plain soil.The results showed that random distribution of waste plastics in the form of flakes and pellets in soil is an effective method for improving the piping resistance of soil.

Analysis of the Properties and Anti-Seepage Mechanism of PBFC Slurry in Landfill

As the landfill leachate has strong pollution on the underground water,surface water and soil.This paper develops the formula of impervious slurry with low permeability,good durability,strong adsorption and retardant based on the bentonite which is modified by polyvinyl alcohol.Through the simulation experiment,the optimum formula of polyvinyl alcohol is 0.2%.Its osmotic coefficient for 28 days is 0.53×10^-8~1.86×10^-8 cm/s and compressive strength is 0.5~1.5 MPa as well.This paper study on the retardant rule of the consolidation of slurry against the pollution in the leachate by self-made percolation instrument.The experiment shows that the retardant rate of the consolidation against inorganic pollutants and organic pollutants is over 85% and the retardant rate against heavy metal ion such as Hg and Pb is above 99%.The slurry has the characteristics of low permeability,high retardant against pollution,good durability and plasticity,no chemical additives,no pollution,wide source of raw materials and good economy which determine it can be used to new landfill or existing landfill,building foundation pit and water conservancy project.

Penetration Resistance of Composite Bucket Foundation with Eccentric Load for Offshore Wind Turbines

The penetration of the composite bucket foundation(CBF)is crucial in its construction process.In actual projects,the foundation is inevitably subjected to eccentric load caused by towers and turbines,as well as wind,wave,and flow,during the one-step installation.Moreover,the eccentric load is bound to affect the penetration method and penetration resistance of the foundation.To examine the above-mentioned issues,the penetration resistance of CBF with eccentric load was calculated and analyzed based on model tests,and the seepage field of the CBF under eccentric load was analyzed using ABAQUS.The influence of different magnitudes of eccentric load and various offset strategies on penetration resistance was analyzed,and the theoretical and measured values were compared.The result indicated that the negative pressure of the offset room was found to be smaller than that of other rooms when the CBF penetrated the soil under eccentric load.The penetration resistance of CBF under eccentric load was larger than that without eccentricity,and the larger the eccentric load is,the greater the penetration resistance.The influence of different eccentric load offset strategies on penetration resistance was found to be negligible.The calculated penetration resistance under eccentric load was in good agreement with the measured value.

Discrimination conditions and process of water-resistant key strata

Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.

Laboratory simulation of CO_(2) immiscible gas flooding and characterization of seepage resistance

CO_(2) flooding can significantly improve the recovery rate, effectively recover crude oil, and has the advantages of energy saving and emission reduction. At present, most domestic researches on CO_(2) flooding seepage experiments are field tests in actual reservoirs or simulations with reservoir numerical simulators. Although targeted, the promotion is poor. For the characterization of seepage resistance, there are few studies on the variation law of seepage resistance caused by the combined action in the reservoir. To solve this problem, based on the mechanism of CO_(2), a physical simulation experiment device for CO_(2) non-miscible flooding production manner is designed. The device adopts two displacement schemes, gas-displacing water and gas-displacing oil, it mainly studies the immiscible gas flooding mechanism and oil displacement characteristics based on factors such as formation dip angle, gas injection position, and gas injection rate. It can provide a more accurate development simulation for the actual field application. By studying the variation law of crude oil viscosity and start-up pressure gradient, the characterization method of seepage resistance gradient affected by these two factors in the seepage process is proposed. The field test is carried out for the natural core of the S oilfield, and the seepage resistance is described more accurately. The results show that the advancing front of the gas drive is an arc, and the advancing speed of the gas drive oil front is slower than that of gas drive water;the greater the dip angle, the higher the displacement efficiency;the higher the gas injection rate is, the higher the early recovery rate is, and the lower the later recovery rate is;oil displacement efficiency is lower than water displacement efficiency;taking the actual core of S oilfield as an example, the mathematical representation method of core start-up pressure gradient in low permeability reservoir is established.

基于冻结指数和日照遮阴程度修正系数的渠道防冻胀保温板厚度计算方法研究

准确计算保温板的厚度是渠道保温防冻胀设计的核心环节。根据渠道试验观测数据绘制了渠基土累计负温过程线,分析了冻结指数和日照遮阴程度修正系数对渠基土冻深的影响,通过Matlab工具拟合求解建立了基于这两个指标的冻土层设计热阻计算公式,并利用黑龙江某灌区渠道冻胀试验数据统计计算结果对本研究提出的计算公式进行合理性验证。结果表明,冻土层设计热阻R0与日照遮阴程度和冻结指数密切相关,渠基土冻深发展变化的全过程和逐日负积温的变化具有同步性,计算结果与试验实际观测结果十分吻合,此公式可以在冻土地区渠道保温板厚度计算中推广应用。

岩心油水两相渗流启动压力梯度实验研究

低渗储层油水两相渗流时存在启动压力梯度,充分认清水驱油时启动压力梯度的变化和影响因素对油藏水驱开发至关重要。为了搞清油藏储层油水两相渗流启动压力梯度特点及其影响因素,对不同渗透率、不同含水饱和度、不同润湿性岩心水驱油两相渗流的启动压力梯度进行了室内实验测定,根据实验现象和实验结果,分析了产生启动压力的岩心孔隙内部的阻力效应和微观成因。研究结果表明:气体渗透率小于50×10^(-3)μm^(2)的低渗岩心随含水饱和度增加,启动压力梯度增大;气体渗透率大于50×10^(-3)μm^(2)的中高渗岩心启动压力梯度随含水饱和度变化不大,总体呈下降趋势,且数值较小;对于低渗油藏,启动压力梯度随岩心渗透率降低而增大,随岩心润湿指数增加而减小;岩心边界层液体厚度越大,启动压力梯度越大。产生启动压力的附加阻力效应有油滴毛管力产生的摩擦阻力、静润湿滞后导致油珠变形产生的阻力及液阻效应产生的阻力,其大小和岩石孔喉半径、润湿指数、微观孔隙的油水分布状态、边界层厚度及固液界面张力有关。

多孔介质中油包水乳状液流动规律及液阻效应

含有胶质和沥青质等天然活性物质的原油在喉道剪切作用下易和水相形成油包水乳状液,产生液阻效应,堵塞地层导致油井产量急剧降低。利用室内岩心驱替实验和微观孔隙流动模拟技术,研究了原油黏度、含水率、乳状液粒径与喉道直径比等因素影响下,油包水乳状液在复杂多孔介质内的流动规律和液阻效应。结果表明,随含水率增加,油包水乳状液的液阻效应增强,导致启动压力梯度增加。当原油黏度为550 mPa·s、乳状液含水率为20%~50%、岩心渗透率为300×10^(-3)μm^(2)时,油包水乳状液的启动压力梯度为12~37 MPa/m。原油黏度对高黏油(550 mPa·s)乳状液启动压力梯度的影响更大,乳状液粒径与喉道尺寸的匹配程度对低黏油(<30 mPa·s)乳状液启动压力梯度的影响更显著。由于液阻效应,水滴在喉道入口处聚集并发生聚并,使油包水乳状液中水滴粒径变大。油包水乳状液粒径与喉道直径比值越大,分散相(水滴)通过喉道时的渗流阻力越大。油包水乳状液的毛细管数越小,液阻效应导致渗流阻力的增加倍数越大。计算表明,当毛细管数为9.9×10^(-4)(低黏油)、乳滴粒径与喉道直径比为2.5或10.0时,液阻效应导致油包水乳状液通过喉道时的渗流阻力增加到孔隙中流动渗流阻力的7倍或35倍。研究结果明确了油包水乳状液在多孔介质中流动的液阻效应及其影响因素,为地层原油渗流和提高原油采收率研究提供理论指导。

岩心多孔介质中乳状液乳化性能评价和驱油效果研究

综合利用全能红外稳定分析仪、光学显微镜及多功能流变仪,从宏观和微观角度开展了不同复合体系在岩心渗流和机械搅拌下生成乳状液的稳定性、黏度及微观形态变化特征实验研究。在此基础上,辅以岩心驱油实验,研究了不同乳状液复合体系的驱油效果。结果表明,甜菜碱表面活性剂二元体系可在岩心多孔介质驱油过程中有效生成乳状液,机械搅拌状态下不同复合体系稳定性差异显著。二元、无碱A、三元体系的机械搅拌剪切与岩心渗流生成乳状液的TSI值具有反向关联的关系,而在乳状液黏度上二者具有正向关联的关系。相比于岩心剪切,机械搅拌剪切应力较大,不同体系生成的乳状液液滴粒径更小,能够更显著地区分出不同体系之间乳状液相态区别。岩心驱油实验过程中,整体渗流阻力与提高采收率幅度存在反向相关的关系,不同等黏度体系提高采收率幅度依次升高,且具有显著的梯度差异,二元、三元、无碱A体系不仅可以通过乳化封堵起到调剖作用,扩大波及体积,进而提高洗油效率,乳化流体还可以进入水驱难以波及的微孔区域中洗油、刮油,通过乳化携带作用,降低残余油饱和度,改善驱油效果。

高密度电法在地下水渗流通道探测中的技术应用

地下水渗流可能会引起土体物理性质改变,引发地质灾害。高密度电法用于地下水探测宏观成像分辨率高,采用高密度电法对某居民区地下水渗流通道进行探测,通过观察分析视电阻率反演图像,追踪低电阻率异常来判断地下水渗流通道及富水区位置,最终发现场区内地下水在重力的作用下由西向东,通过地下车库顶板上方和地下车库外墙间两个渗流通道,在场区东南侧汇聚成富水区,造成下方毛石护坡局部涌水。该推断为下一步处理方案设计提供了准确的依据。

桥梁混凝土防腐蚀方法及其评价

为提升桥梁混凝土的耐久性,文中在对桥梁混凝土防腐蚀方法介绍基础上,提出了三种防腐蚀处治方案,并对其防腐蚀效果进行评价。结果表明,聚合物砂浆防腐、硅烷浸渍及复合防腐三种防腐蚀方案均能实现防腐蚀功能;采用聚合物砂浆以及复合防腐方案进行处理的混凝土试件,在经过4 d浸水及100次快速冻融循环后,其渗水深度及质量损失率均明显小于硅烷浸渍组试件,表明这两种方案的防腐性能更优。

基于疏水涂层改善混凝土防渗抗冻性的效果对比

在黑龙江省等高纬度寒冷地区,冬季降雪频繁,公路路面、桥面上的冰雪较多,出于交通安全和保通需要,降雪前后时常会在路面、桥面上撒布一定数量的除冰盐,容易导致路面、桥面的剥蚀损害,对桥梁混凝土钢筋的使用寿命也有较大影响。在混凝土表面进行疏水处理是改善混凝土防渗及抗冻性的有效措施之一。基于“氟化二氧化硅胶体”类疏水材料进行室内对比试验,确认采取常用涂布方式进行处理,可使混凝土的表面静态接触角达到145°以上,采取两遍喷涂或“先涂刷后喷涂”的方式效果最好。与未进行表面处理的试件相比,吸水率可降低68.3%;在冻融循环次数150次以内时,质量损失率可降低53.3%,100次以内时,抗弯拉强度损失率可降低79.5%。同时在抗盐冻,以及表面疏冰方面也有积极作用。

高密度电阻率法在调蓄水池渗流勘察中的应用

对高密度电阻率法在调蓄水池渗流勘察中的实际应用进行了研究,结合钻孔、探井等物探手段,分析高密度电阻率法的数据真实性,提出相应处理建议。

饰面高性能混凝土在地铁工程中的技术运用研究

随着城市化进程的加快和城市交通需求的不断增长,地铁作为城市主要的公共交通方式,其建设和发展日益成为城市规划和交通基础设施建设的重要组成部分。在地铁工程中,饰面高性能混凝土(HPC-SF)作为一种技术先进、性能优越的建筑材料,因其在耐久性、抗裂性和施工效率等方面的显著优势,逐渐成为地铁车站、隧道及相关结构中的首选材料之一。本文通过对HPC-SF在地铁工程中的应用实例和技术探讨,探索其优化应用的途径和策略,为地铁工程的可持续发展提供理论支持和实际指导。

流体在外加直流电场作用下的电动-水力渗流特性

建立了外加电场作用下储层孔隙中流体的电动 -水力渗流模型 ,并通过实验研究了外加电场作用下的电动-水力渗流特性 .结果表明 ,极性流体在储层孔隙中的电动 -水力渗流特性除了与其粘滞阻力、压力、重力等因素有关外 ,还与自然电场等因素有关 ,且外加电场可改变流体的渗流特性 .将电动力方向与水动力方向一致的电场定义为正向电场 ,反之则为反向电场 .在正向电场作用下 ,阻力因数小于 1,渗流速度随着电场强度的增大而增加 ;在反向电场作用下 ,阻力因数大于 1。

低渗透储层水驱油渗流阻力特征

低渗透储层物性差、孔喉细小,水驱油过程中渗流阻力较大,注采井间难以形成有效的驱替压力梯度,建立渗流阻力的描述方法、研究渗流阻力的影响因素和变化特征对低渗透储层注水开发具有重要意义。在油水流动质量守恒定律的基础上,建立了低渗透储层水驱油渗流阻力梯度数学模型,应用水驱油渗流阻力梯度变化率函数分析水驱油渗流阻力梯度的变化特征,为低渗透储层中水驱油渗流阻力梯度的描述提供一种宏观表征方法。理论分析表明:低渗透储层水驱油渗流阻力梯度呈非线性特征,随着含水饱和度的增加水驱油渗流阻力梯度先增加后减小。低渗透储层注水开发存在最大渗流阻力梯度,与油相粘度、储层渗透率和注入速率相关;低渗透储层注水速率越大,需要克服的最大渗流阻力越大;油相粘度越大,最大渗流阻力越大;储层渗透率越低,最大渗流阻力越大。

砾石土防渗料-反滤料联合抗渗试验

防渗料在高水头作用下是否发生渗透破坏,在很大程度上取决于设置在其后的反滤料对防渗料的保护效果。利用自行改造的竖向渗透破坏仪,在大量砾石土防渗料和反滤料的竖向联合渗透破坏试验的基础上,研究了防渗料砾石含量、干密度及反滤料的级配、干密度和厚度对防渗料与反滤料联合抗渗性能的影响规律,分析了试验过程中初始临界坡降的出现机理和自滤反滤层的形成过程。研究表明,试样的初始临界坡降随防渗料和反滤料干密度的增大而增大,随防渗料砾石含量、反滤料控制粒径D15的增大而减小,随反滤料厚度的增加而增大。

喷涂聚脲弹性体技术在尼尔基水利工程中的应用

喷涂聚脲弹性体技术是一种新型无溶剂、无污染的绿色施工技术。为了解决尼尔基水利枢纽工程混凝土蜗壳防渗及抗冲磨问题,首次大规模应用了喷涂聚脲弹性体技术。通过对聚脲弹性体材料特性、专门的喷涂设备、喷涂施工工艺及注意事项的介绍,为今后推广应用该技术提供了宝贵的经验。这种技术在解决水利水电工程中抗冲磨、抗渗及防腐蚀等方面具有广阔的应用前景。