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1.
Electro-Osmotic Consolidation Experiments on an Organic Soil 总被引：4，自引：4，他引：0
A series of electro-osmotic consolidation experiments were carried out on an organic soil from the central Sarawak region
of Malaysia. Commercially available EVD was used to induce electro-osmosis and drainage of pore water. The influence of the
method of drainage and pumping interval of drained water on electro-osmotic consolidation was investigated. The combination
of electro-osmotic consolidation and chemical stabilization techniques was investigated by installing lime or cement columns
near the anode end of the test bed. The binder factor in the lime and cement columns was varied. The paper presents the experimental
set-up, test procedures, experimental program, results and conclusions of the study. Electro-osmosis, using EVDs, was effective
in the electrokinetic treatment of the organic soil. The two types of drainage, namely drainage at bottom and drainage tubes,
were effective. Electro-osmotic consolidation improved with decrease in pumping interval. The lime and cement columns, used
in combination with electro-osmosis, increased the undrained strength further. 相似文献
2.
为深入研究电渗排水对土体工程性质的影响,采用铁丝为电极,在模型箱内对南京市某河道淤泥质土进行电渗排水
模拟试验。电渗前后土的物理力学性质对比分析表明：电渗后土体的液、塑限与塑性指数均降低;电渗前后土体在相同含
水量和干密度情况下进行直接剪切试验,发现电渗后土体的凝聚力和内摩擦角均降低,即电渗后土体在特定情况下出现了
强度衰减的现象。论文基于土中阳离子流失机理对土体在特定情况下的强度衰减现象进行了微观解释。另外,利用提出的
新的电渗机理从微观角度解释了电渗过程中土体开裂现象,阳极因快速失水,最早出现裂隙,但裂隙延展范围较小;阴极
含水量始终高于阳极,且失水速度较慢,裂隙延展范围较大。值得一提的是,在以往的研究中并未关注到电渗加固过程中
土中阳离子流失对电渗后土体性质的影响。 相似文献
3.
边坡电渗模型试验及能量分析法数值模拟 总被引：4，自引：0，他引：4
采用导电塑料制成的电动土工合成材料(EKG)进行了15.5 d的边坡电渗加固试验,测定了电渗之后土体等含水率分布曲线。试验结果表明,电渗加固效果是随时间从阳极到阴极逐渐扩展的,因此,越靠近阳极接入点的土体加固效果越好,越靠近阴极末端的土体加固效果越差。提出了电渗能量分析法,该方法仅要求黏性土体在排水固结开始的初始时刻是处于饱和状态,而在排水固结进行的过程中土体可以是饱和的,也可以是非饱和的。提出了基于能量分析法的电渗过程数值模拟方法,并对试验过程进行了数值模拟,模拟结果与实测结果能够较为吻合。 相似文献
4.
电渗固结是促进低渗透性软土排水固结的有效方法。为了揭示不同电势梯度影响高岭土电渗固结的基本规律,在自制电渗试验装置上对高岭土进行电渗试验。试验过程中测量电流、排水量、沉降量以及有效电压随时间的变化,并进行单位排水能耗分析。基于电渗固结多场耦合控制方程,实现土体电渗固结全耦合分析的有限元数值方法,计算结果与解析解吻合良好,验证了程序的有效性。为预测不同电势梯度下土体沉降量随时间的变化关系,分别对0.5,1.0,1.5 V/cm 3种电势梯度电渗固结试验进行数值模拟分析,获得模型表面沉降量分布、阳极超静孔隙水压力时空发展规律、阳极位置固结度等曲线,计算结果和试验结果吻合良好,可为实际电渗试验提供理论指导。 相似文献
5.
针对真空预压作用下排水板淤堵与排水条件受限等问题,提出絮凝−真空−电渗联合加固法。首先通过沉降柱试验确定合适的有机絮凝剂,然后采用该絮凝剂,分别在 48 h（开始介入真空预压,固结度为0 ）、60 h（排水速率明显下降,固结度为60%）及 84 h（排水速率近乎 0,固结度为 80%）时介入电渗,开展不同电渗介入时间的絮凝−真空−电渗联合加固试验。试验从排水量、十字板剪切强度、含水率与孔压等对比分析联合加固的有效性,确定其最佳电渗介入时间。试验结果表明：当固结度为 80% 时介入电渗,絮凝−真空−电渗联合加固法能够有效地抑制排水速率减小的趋势,增长有效排水时间。同时,土体的抗剪强度和承载力亦得到大幅提升,孔压消散更加均匀。此外,在阳离子聚丙烯酰胺絮凝剂的作用下,初始排水速率快,在一定程度上使土体的渗透性得到提升,有效地解决了排水板淤堵问题,说明絮凝−真空−电渗联合加固法具有较强的优越性。 相似文献
6.
针对传统电渗法治理淤泥质土过程中排水效率低且治理后土体不均匀等问题,从改变软黏土颗粒自身持水特性角度出发,提出采用新型有机高分子材料阴离子型聚丙烯酰胺（APAM）联合电渗法治理淤泥质土的思路。利用自制的一维电渗固结试验装置,探究絮凝−电渗法联合作用机制以及不同絮凝剂掺入比对电渗排水加固效果的影响规律。试验结果表明：与传统电渗法相比较,絮凝剂 APAM 的掺入减少了软黏土颗粒表面的结合水膜厚度,使得淤泥质土的前期电渗排水速率和累计排水量显著提升,从而降低了电渗法的平均能耗系数;同时,絮凝剂高分子长链的“吸附架桥”作用增强了土颗粒的黏结力和絮凝沉积效果,有效缓解了电渗过程中细小黏粒迁移集聚而造成的阴极淤堵问题;治理后淤泥质土的抗剪强度大幅增高,土体的均匀性也得到了明显改善,且当絮凝剂 APAM 掺入比为 0.30% 时,土体的电渗排水固结效果最佳。 相似文献
7.
Electrokinetic remediation of metal contaminated glacial tills 总被引：2，自引：0，他引：2
This paper presents the results of an experimental investigation which studied the feasibility of using the electrokinetic process to remediate contaminated clays of glacial origin, otherwise known as glacial tills. An overview of the electrokinetic phenomena, as well as previously performed laboratory and field investigations, is first presented. The methodology of the electrokinetic experiments which were conducted to investigate the removal of metals from a glacial till is then described. A total of 16 experiments were conducted using glacial till samples obtained from a project site near Chicago. Sodium and calcium were used as the surrogate cationic metallic contaminants. These experiments demonstrated that ion transport during the electrokinetic process occurs due to both electro-osmosis and electromigration, but that due to electromigration is significantly higher than that due to electro-osmosis. Unlike other clays such as kaolinite, the glacial till used for this investigation possessed high buffering capacity because of its high carbonate content which prevented the acid front migration from the anode to the cathode during the electrokinetic process. The ion removal efficiency of the electrokinetic process was found to increase when: (1) the voltage gradient applied to the soil was increased, (2) the initial concentration of the contaminants was increased, and (3) the duration of the treatment process was increased. The ion removal efficiency was also greater for smaller ions which possess less ionic charge and when the ions existed independently in the soil as compared to when they coexisted. This investigation suggests that the electrokinetic process has significant potential for remediating glacial tills contaminated with metals. However, the properties of Na and Ca are not representative of contaminants, such as heavy metals, so further investigations are needed. 相似文献
8.
为解决目前电渗应用的高能耗困境及大尺寸模拟困难等问题,提出针对低渗透性、高含水率土体的电动-水力渗流协同作用的三维固结方法。自行研制了一套阴极-集水-排水协同作用的多功能集排水系统,采用间歇式抽水代替连续抽水。采用三维电动-水力渗流固结系统对取自贡湖湾湿地和白旄堆场的2种不同太湖底泥进行了电渗试验研究,同时对白旄堆场太湖底泥进行了传统一维电渗固结试验,并对2种试验条件下的单位体积排水能耗和单位体积单位排水量能耗等关键指标进行了对比。结果表明：三维集水井设计可大大降低土体阴极附近电阻,间断性提高系统电流,提高排水效率,降低电渗总能耗;间歇式抽水可间歇性降低系统内总电流,利用电动-水力协同作用,保持系统渗流的连续性;三维电动-水力渗流固结系统的电流呈周期性减小—增大模式,并且降低速率较慢,尤其对于有机质含量较高的土体,电渗过程电流始终保持在一个较高的水平,提高了排水固结效率。三维电动-水力渗流固结系统的单位体积排水能耗和单位体积单位排水量能耗分别约为一维电渗系统的2/3和1/30。在高含水量软土固结排水中具有显著的节能效果。三维电动-水力渗流固结系统可以提高排水固结效率、大幅度降低能耗,为... 相似文献
9.
10.
通过室内1:5的模型试验进行了等电势梯度下2 m×1 m和1 m×0.5 m两种工程常见矩形布置电极间距下的软黏土电渗性状的研究。利用监测排水量、排水速率、电流、电势、含水率和pH值等指标,对不同电极间距试样的电渗处理效果、能量效率和电极腐蚀等方面进行了分析。结果表明：保持电势梯度不变而减半电极间距能够加快电渗排水,降低土体含水率,减小能量消耗和电极界面电阻,但也会导致土体pH值变化和阳极腐蚀量的增大。此外,采用较小的电极间距可使损失在电极和土接触面上的电势降减小,但损失的电势降占电源电压的比例增大。 相似文献
11.
12.
研究发现,通电作用下冻土中的未冻水会发生迁移,这种持续的迁移是一个复杂的物理化学过程,并最终伴随着冻胀的过程。为了探究这一电场作用对冻土的影响,选取冻结冻胀敏感性较高的粉质兰州黄土作为研究对象,分析其在3、4和5 V?cm-1电势梯度作用下的阴阳极变形量、通电前后水分分布规律和电流及电能损耗。结果表明：随着电势梯度的增大,土体阴阳极变形量的差值逐渐增大,且阴极都发生膨胀,阳极发生沉降;随着电势梯度的增大,水分由阳极至阴极的迁移量增大,电流降低的幅度增大,两者变化特征与含水率差值变化特征类似;在5 V?cm-1的电势梯度下,电能总能耗最大,单位含水率能耗最小。 相似文献
13.
富含有机物质是泥炭土工程性质不良的主要原因。不同有机质含量及组分的泥炭土,其物理力学性质差异很大。为明确有机质含量的影响,对数十组不同有机质含量无定形泥炭土试样进行一系列室内试验,系统分析了物理、变形、强度及渗透性随有机质含量的变化规律;为比较有机质组分不同导致的工程性质差异,将以上无定形泥炭土物理力学指标与纤维泥炭土试验数据进行系统分析。结果表明:无定形泥炭土基本物理力学指标与有机质含量间有一定的线性关系,其中,初始孔隙比（e0）、天然含水率（w0）、液塑限（wL、wp）、黏聚力（c）随有机质含量增加线性增大,比重（Gs）、固结系数（Cv）和内摩擦角（φ）随有机质含量增大而减小。相较无定形泥炭土,纤维泥炭土比重小、含水率大、孔隙比大。抗剪强度方面,无定形泥炭土黏聚力随有机质含量增大而增大,较纤维泥炭土略高;内摩擦角随有机质含量增大而有下降趋势,约为纤维泥炭土的1/5～1/14。渗透性方面,无定形泥炭土的初始渗透系数（kv0）及渗透指数（Ck）随有机质含量增大而减小,且普遍小于纤维泥炭土。 相似文献
14.
Hossein Moayedi Mansour Mosallanezhad Ramli Nazir Sina Kazemian Bujang Kim Huat 《Geotechnical and Geological Engineering》2014,32(4):933-947
Peat is known as soft soil with low shear strength and high compressibility. Electrokinetic injection technique is being used by applying a direct electrical potential across the soil specimens to improve physicochemical characteristics of the peat. Such applications cause electrochemical effects on the soil, leading to changes in the soil’s chemical, physical, and mechanical properties. This paper presents the results of the undrained shear strength, pH, water content across the electrokinetic box after injecting the cationic grouts. Four cationic grouts namely; calcium chloride, calcium oxide, Aluminum hydroxide, and sodium silicates were selected as grout. The microstructures of the stabilized peats were investigated by scanning electron microscopy and energy dispersive X-ray spectrometer analysis. The result showed that the cationic stabilizer injected by the electrokinetic technique could significantly increase the peat soil’s shear strength. Furthermore, the result showed that the effect of calcium oxide was the highest on the shear strength of peat due to its physico-chemical properties. The shear strength, pH and moisture content of peats across the electrokinetic box also altered depending on the used electrolytes and time. 相似文献
15.
In present study, the non-linear variations of soil compressibility, hydraulic and electro-osmosis conductivities were analyzed through laboratory experiments, and incorporated in a one-dimensional model. The analytical solutions for excess pore water pressure and degree of consolidation were derived, and numerical simulations were performed to verify its effectiveness. The results indicated that both the non-linear variations of hydraulic and electro-osmosis conductivities showed remarkable impacts on the excess pore water pressure and degree of consolidation, especially for soils with relative high compressibility. A further comparison with previous analytical solutions indicated that more accurate predictions could be obtained with the proposed analytical solutions. 相似文献
16.
In this paper, a numerical solution for the electro-osmosis consolidation of clay in multi-dimensional domains at large strains is presented, with the coupling of the soil mechanical behaviour, pore water transport and electrical fields being considered. In particular, the Modified Cam Clay model is employed to describe the elasto-plastic behaviour of clay, and some empirical expressions are used to consider the nonlinear variation of the hydraulic and electrical conductivities of the soil mass during the consolidation processes. The implementation of the theoretical model in a finite element code allows for analysis of the evolution of the transient response of the clay subjected to electro-osmosis treatment. The proposed model is verified via comparison with data from a large strain electro-osmosis laboratory test, to demonstrate its accuracy and effectiveness. Various numerical examples are also investigated to study the deformation characteristics and time-dependent evolution of the excess pore pressure. Finally, a well-documented field application of electro-osmosis is simulated to provide further verification. The results show that the numerical solution is effective in predicting the nonlinear behaviour of clay during electro-osmosis consolidation. 相似文献
17.
M. Gholami D. Yousefi Kebria M. Mahmudi 《International Journal of Environmental Science and Technology》2014,11(5):1433-1438
One large group of persistent and toxic contaminants is the hydrophobic organic contaminants. Among them, perchloroethylene (PCE) has been recognized as a representative group of these pollutants with low solubility. This study reports on the effects of electrokinetic remediation with non-ionic surfactant on PCE-contaminated soil. The performance of electrokinetic process was investigated in the treatment of clay soil that artificially contaminated with two levels: 10,000 and 30,000 mg/kg PCE and 0.33 g/kg Triton X-100. A DC power supply with electric voltage (1 V/cm) was used for 8–16 days. A negatively charged soil surface resulted in a more negative zeta potential and greater electroosmotic flow toward the cathode. The PCE was measured after extraction using n-hexane and analyzed by Fourier transform infrared spectroscopy instrument. The water content of soil was kept 25 % (w/w). Results were shown that PCE removal efficiency achieved was 74 and 89 % for 10,000 and 30,000 mg/kg PCE, respectively, for 16 days. Therefore, in this study, the integration of electrokinetic with non-ionic surfactant as a hybrid method was most effective for the remediation of PCE-contaminated soils. 相似文献
18.
One of the most cost-effective in situ technologies for soil and groundwater (i.e., aquifer) remediation is electrokinetic remediation. In electrokinetic remediation, electromigration due to electric field is combined with hydromigration due to hydraulic flow by purge water to remove pollutants from aquifers through the pore water. This study aims at investigating theoretically the role of electromigration (as active movement) of pollutants and the role of hydromigration (as passive movement) of pollutants in electrokinetic remediation, and making it clear that the control variables for electrokinetic remediation are the applied voltage and the hydraulic flow rate. These aims are pursued by construction of a mathematical model based on physico-chemical considerations and by model simulations of the electrokinetic remediation applied to the virtual aquifer polluted by heavy metals of copper sulfate. According to numerical simulations with the model: (1) heavy metal (nonanionic copper) is removed from the upstream anode region and accumulated in the downstream cathode region; (2) to carry away the heavy metal outside the aquifer (global removal), hydromigration by purge water flow is essential; and (3) electromigration contributes mainly to the redistribution of heavy metals within the aquifer (local removal and local accumulation). 相似文献
19.
Alireza Ebrahimi Fahadani Masoud Oulapour Nematollah Jaafarzadeh 《Arabian Journal of Geosciences》2018,11(21):671
Electro-remediation process (ERP) is used for dewatering and decontaminating of the soil and improving its mechanical properties. In this study, the effect of voltage, electrode materials, and their arrangement on ERP were studied. The saturated clayey soil was remolded in four boxes at a dry density of 16.2 kN/m3. The process was performed in three stages. The chemical tests at the end of ERP indicated that the absorption of chloride ions in the anode may differ from 89 to 642% due to electro-migration phenomenon. The pH of the soil decreases in anode zone and increases towards the cathode zone. Up to 92% of the sulfate ions were transported and accumulated in the anode. However, in highly contaminated soil, the absorption ratio is 5% in the cathode due to the domination of electro-osmosis process. It was indicated that the electro-osmosis permeability coefficient (Ke) depends on the applied voltage, the soil type, and temperature and its reduction versus time is inversely related to applied voltage. Also, sulfate ions reduced by 74% in the anode due to a change in absorption direction. The results showed that the optimum configuration is linear along with a voltage of 18 V. 相似文献
20.
采用辽宁沿海地区淤泥质软土对铁、铜、铝和新型复合电极等不同电极材料进行室内电渗排水固结试验,从有效电势、电流、排水量与排水速率、能耗、电渗后土体含水率和承载力等对电渗效果进行分析。新型复合电极材料是由碳纤维、塑料排水板与铁片组成,其充分利用各种材料的优点,既解决了铁与碳纤维直接相连通电后易断的问题,又解决了电极腐蚀严重的问题。多组试验结果表明：新型复合电极材料的电渗排水固结使土体的加固强度提升较高,且相对均匀,加固强度达到160 kPa以上的土体面积占加固总面积的75%,说明新型复合电极材料的优越性。金属电极的腐蚀较为严重,且主要发生在阳极。根据电渗后阳极的腐蚀比,新型复合电极的腐蚀量明显低于金属电极,且新型复合电极可提高加固效果,节约电极材料成本。 相似文献