Terzaghi一维固结顶面不排水解

解答了顶面不排水、底面排水边界条件下的太沙基一维固结微分方程,并比较分析了不同坐标系统下、不同边界条件下的单面排水太沙基一维固结微分方程的解答。发现由于太沙基一维固结理论是建立在荷载作用面为无限大的假定之上,且不考虑土体与水的质量,因此顶面不排水、底面排水解与顶面排水、底面不排水解在两种坐标系统下具有等价关系。     

微小三角形槽道内电渗流动特性分析

提出了微小三角形槽道内电渗流动理论计算方法，通过Galerkin法计算并分析了其内部的电势及速度分布，获得了温度、槽道尺寸、外加电势的电场强度、ζ电势以及电解质浓度对微小三角形槽道内电渗流动的影响规律。计算结果表明：微小三角形槽道内液体的质量流量随ζ电势、电场强度、流体温度及电解质浓度的增加而增加，随微小三角形槽道尺寸的增加先增加后减小。     

强夯法在滨海储运项目场平处理中的应用

福建某石化码头储运项目场地陆域形成堆载预压排水固结处理不到位,为达到排水固结、土体密实的目的,该项目采用强夯法对场地进行二次处理,使得强夯处理后的场地符合工程对沉降的要求。     

降雨对土坡稳定的影响

为了模拟降雨过程中边坡土体强度的变化,以室内常规不固结不排水三轴试验为基础,探讨了含水量的变化对土体抗剪强度参数及应力-应变关系的影响,并从孔隙水压力的角度探讨了降雨过程中含水量的变化对土体变形的影响.试验结果表明:抗剪强度参数与含水率变量总体上呈非线性关系,但对于粘聚力(c)和内摩擦角(φ),在含水质量分数为18.64%处均达最大值,并且随着含水量的增加,c、φ值均单调递减;重塑黏性土的应力-应变关系呈近似双曲线,并且随着含水量的增减应力-应变关系曲线越来越接近两边的坐标轴.最后,从土体强度和变形的两个角度分析可知,降雨过程中所造成的含水量的提高最终导致了边坡的破坏.     

电渗-帽封联用技术对底泥内源污染释放的阻控效果

近年来关于河湖底泥内源污染的原位控制技术受到了广泛的关注和应用。本文针对水体底泥内源污染的释放问题,研究了“电渗-帽封”联合技术的控制效果。电渗处理试验结果表明,电压越高,电渗处理后底泥向上覆水中释放的氨氮量越低,但总磷释放量升高。后续的帽封试验结果表明,使用天然粗河砂效果最好,且帽封厚度越高,材料粒径越小,对污染物释放的控制效果越好。采用20V电渗电压预处理实际底泥,并采用3～5mm粒径的天然粗河砂作为帽封材料,在3cm帽封厚度条件下,对污染物释放的阻控效率可达到66.9%。本研究的结果表明,“电渗-帽封”技术具有良好的底泥污染阻控效果,可以作为一种有效的原位处理方法来阻止底泥内源污染的释放,但其潜在的生态环境效应还需要进一步关注。     

边坡稳定有限元分析及其应用

本文概述了边坡稳定分析的极限平衡法和有限元法的优缺点,分析了土体二维固结有限元计算原理及圆弧分析法理论,在此基础上.建立了一种稳定分析及变.开;计算方法,编制了一套考虑土体非线性有限元法固结变形及稳定分析程序,并结合湖南铁山土坝进行了计算分析。     

基于大孔硅胶电渗再生的正交回归实验

电渗再生固体除湿剂具有节能、环保、安全的优点,近年来得到广泛关注。本文以大孔硅胶电渗再生过程中的电流变化为实验指标,以电压和含水量为影响因素设计正交回归实验,确立各因素与实验指标之间的多项式回归方程,分析各因素对实验指标的综合影响程度。结果表明,大孔硅胶在含水率较高和合适的电压下具有较为明显的电渗效应。该实验方法对固体除湿剂电渗再生研究提供了新的思路。     

混凝土与碳纤维混凝土材料的电阻率变化研究

制备了素混凝土及纤维含量不同的碳纤维混凝土材料,并对其在循环电压加载下的电阻率进行了测试。分析表明,电场对材料的电阻率有很大的影响,随着电压加/卸载循环次数的增加,素混凝土的电阻率逐渐升高,直至内部的水化再次达到平衡时,电阻率保持不变;在同一次循环中,卸载时的电阻率高于加载时的电阻率。加入碳纤维后,混凝土的电阻率变化幅度变小,电场对电阻率的影响变弱,并且阐述了引起这种变化的原因。     

基于均匀化理论的一维固结问题研究

根据均匀化理论推导了张量形式的等效宏观模量和细观应变分布张量,进而推导了非均质的各向同性线弹性土体的固结方程。最后就某一典型一维固结问题对该固结方程进行了计算,其结论与用B iot固结方程、TT法(太沙基总应力法)所得结果一致,从而验证了该方法的有效性。     

考虑时间效应的预制桩单桩极限承载力解析解

从饱和软土中沉入预制桩单桩引起的三维超静孔隙水压力的消散和桩周土的固结出发,结合桩土接触面的破坏形式,获得了考虑时间效应的单桩极限承载力的解析解,实现了对任意时刻单桩极限承载力的预测。分析了土体参数的变化对单桩极限承载力的影响,结果表明:桩的最终极限承载力增量随摩擦角的增大而增大;固结系数决定着桩的极限承载力在初期的发挥,但并不影响桩的最终极限承载力。计算结果与工程实际测量吻合较好。     

Laboratory investigation of electro-osmosis effects in saturated dredger fill—a comparison with the stack preloading

A set of unconventional electro-osmosis (EO) experiments using intermittent current was conducted on dredger fill samples from a land reclamation site at Liaoning Coast in China. This study focused on the quantitative evaluation of the use of EO to enhance the effect of surcharge preloading consolidation, thus improving the mechanical and physical properties of soil. The sand wells were used to avoid excessive consumption of electrical energy in the process of repeated seepage. A systematic comparative study on preloading combined with electro-osmotic consolidation shows that the EO coefficient decreases with water content. The increase in shear strength at a potential difference of 15?V combined with a loading of 2.67?kPa is approximately twice as high as that of preloading only, but the electrical power consumption is merely 23% more. Mercury injection tests and scanning electron microscopy images showed that the subsidence mechanism of Liaoning Bay soil is the change of macropores to mesopores. Furthermore, using the combined method of EO and preloading results in even treatment effects in different soil depths. Electrochemical reaction and economic benefit are further analyzed. All of these results indicate that combining preloading and EO ensures better performance than individual operation.     

Injection of saline solutions to improve the electro-osmotic pressure and consolidation of foundation soil

Injection of saline solutions can enhance the effect of electro-osmotic pressure. This study considers the consolidation and stability of foundation soil for building construction. Kaolinite (KGa-1) and Taipei silty clay were subjected to zeta potential (ZP), electro-osmosis and laboratory vane shear tests with injection of saline solutions. The ZP values decrease (i.e., less negative potential) with increased cationic valences and concentrations. The increased electro-osmotic permeability from injecting CaCl₂ (1 N, EOC5) solution is about 172% higher than that without injection due to an increase of drained water from the cathode and the resulting increase of undrained shear strength. Average undrained shear strength for injecting CaCl₂ solution over a period of 7 days is about 4 to 5 times greater than that without injection during electro-osmosis tests. Electro-osmosis tests with injection of saline solutions reveal that the increase of undrained soil shear strength (ΔS_u) is proportional to the ZP tests.     

Electro-Osmotic Dehydration of Hangzhou Sludge with Selected Electrode Arrangements

Electro-osmosis is considered a promising technique for the dehydration of sludge with low permeability and high water content. With little information available on the optimal electrode arrangement for electro-osmosis, comparisons of rectangular, hexagonal, and staggered arrays were performed based on laboratory experiments and theoretical analysis. Experimental results identified that favorable electro-osmotic effects were produced by the hexagonal array with regard to drainage, water content, and shear strength of treated soils compared to the other two arrays examined; the average coefficient of energy dissipation of the hexagonal array was 39% lower than that of the rectangular array and 53% lower than that of the staggered array. This finding demonstrates that the hexagonal array consumed less energy. To describe the electro-osmotic efficiency, the effective electric field theory previously proposed was used to calculate proportions of effective field areas; the results show that the hexagonal array performed best, followed by the rectangular and finally the staggered arrays. It is thus concluded that the hexagonal array was most effective and was thus recommended as the primary pattern for application. The validity of the effective electric field theory in estimating electric field distributions for electro-osmosis was also confirmed by comparing theoretical predictions and experimental results.     

PRACTICAL ASPECTS OF DEWATERING ENHANCED BY ELECTRO-OSMOSIS

ABSTRACT

Dewatering mechanism due to electro-osmosis is fairly different from that of mechanical dewataine which has been used conventionally. and electro-osmotic dewatering has Several advantages compared with the mechanical dewatering and it can be remarkably effective for hardly dewaterable sludges such as very fine Particles and gelatinous materials. In electro-osmotically enhanced dewatering, however, it would be a great problem that the achievement of complete water removal within the sludge could not be possible in principle. Because. when a liauid state in the sludge becomes to be not continuous gradually with proceeding of dewatering, the sludge does not lead electricity and and then electro-osmosis is no longer caused.

Applying electro-osmosis to sludge dewatering practically, methods for improvement of the electro-osmotic dewatering must be investigated taking account ofapos;such a situation for the performance of high dewatering efficiency. Some practical applications of the dewatering which can be considered to be available are described in this paper.     

PRACTICAL ASPECTS OF DEWATERING ENHANCED BY ELECTRO-OSMOSIS

Dewatering mechanism due to electro-osmosis is fairly different from that of mechanical dewataine which has been used conventionally. and electro-osmotic dewatering has Several advantages compared with the mechanical dewatering and it can be remarkably effective for hardly dewaterable sludges such as very fine Particles and gelatinous materials. In electro-osmotically enhanced dewatering, however, it would be a great problem that the achievement of complete water removal within the sludge could not be possible in principle. Because. when a liauid state in the sludge becomes to be not continuous gradually with proceeding of dewatering, the sludge does not lead electricity and and then electro-osmosis is no longer caused.

Applying electro-osmosis to sludge dewatering practically, methods for improvement of the electro-osmotic dewatering must be investigated taking account ofapos;such a situation for the performance of high dewatering efficiency. Some practical applications of the dewatering which can be considered to be available are described in this paper.     

Dewatering effect of vacuum preloading incorporated with electro-osmosis in different ways

The dredger fill dewatering effect of vacuum preloading incorporated with electro-osmosis in different ways was evaluated by implementing six laboratory tests. The results of these tests show that the asynchronous consolidation effect of vacuum preloading incorporated with electro-osmosis was better than the other tests. However, vacuum preloading and electro-osmosis will not be able to give full play to the drainage effect, if the alternate time is too short. Alternatively, the energy provided by vacuum preloading and electro-osmosis will not be able to make full use, if the alternate time is too long. There are some advantages when using vacuum preloading and electro-osmosis asynchronous reinforcement. The alternate time of vacuum preloading and electro-osmosis has to constantly adjust according to the water discharge or drainage rate in engineering application.     

固体除湿剂电渗再生

Due to its energy saving, the solid desiccation system has more and more applications. However, the regeneration of the system is beset with high operating cost and complicated equipment. In this study a new electro-osmotic regeneration method was proposed, and the feasibility was explored experimentally. An electro-osmotic regeneration system with a sample box, controlling and measuring apparatus was set up, and its performance was evaluated. In the experiment, an obvious electro-osmotic regeneration effect was observed for the solid to desiccant in the humid air at normal temperature, and the maximum regeneration rate reached 0. 21 g·m^-2·s^-1. It was found that the whole electro-osmosis process was divided into three phases because of the Joule heating effect and electrode corrosion, which hindered the electro-osmotic regeneration. The experiment showed that the Joule heating effect could be reduced by controlling the supplied electric field at the initial stage.     

Comparison of Electro-Osmosis Experiments on Marine Sludge with Different Electrode Materials

One-dimensional laboratory electro-osmosis experiments of marine sludge in Dalian (China) were conducted on a self-made apparatus to research consolidation effects of copper, aluminum, and ferrum electrodes. Although there was potential loss in the contacts of the anode and marine sludge, the electro-osmosis method was still found to be an effective way to reduce the moisture content and increase the shear strength of marine sludge. In particular, ferrum electrodes performed the best for Dalian coastal marine sludge. The bad performance of copper anode can be justified by the generation of non-conductive paratacamite, atacamite, and nantokite on its surface. Overall, these new discoveries can benefit the choice of electrodes in the marine sludge electro-osmosis dewatering application.     

Vacuum Preloading Combined with Electro-Osmotic Dewatering of Dredger Fill Using Electric Vertical Drains

Based on the vacuum preloading combined electro-osmotic consolidation method, a site comparison trial of vacuum preloading and vacuum preloading in combination with electro-osmotic consolidation was performed on Li Island, Hubei Province. The performance and drainage effects of electric vertical drains were evaluated. The problems were analyzed by monitoring test results. Test results from the field showed that the water content of the dredger fill was greatly reduced and the physico-mechanical properties and bearing capacity were improved significantly after 28 days of treatment by vacuum preloading in combination with electro-osmotic consolidation. Compared with the vacuum preloading method, vacuum preloading in combination with the electro-osmotic consolidation method using electric vertical drains reduced the construction time, saved energy, and achieved an ideal reinforcement effect.     

An overview of electro-osmosis in fuel cell polymer electrolytes

Electro-osmosis, the transport of water with protons, in polymer electrolyte fuel cell membranes is important because it effects water management within an operating cell on both a global and local level. The electro-osmotic drag coefficient is the number of water molecules transported per proton and is a quantitative measure of the extent to which electro-osmosis occurs in a given polymer electrolyte. The methods for which electro-osmotic drag coefficients have been determined are reported. An effort is made to report proton electro-osmotic drag coefficients extensively, while a few non-proton cation electro-osmotic drag coefficients have been chosen for illustrative purposes. The results reported have implications for fuel cell performance and in the development and characterization of new polymer electrolyte membranes.