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.     

The characteristics of electric vertical drains in electro-osmotic dewatering

The product performance and drainage effect of electric vertical drains (EVDs) were evaluated by implementing field tests. A small number of electrodes were inserted into the field site and were electrified with different operation modes. The results of the field tests show that the largest range of the current for each pair of electrodes is 1.5–2 A in this dredger fill. A high-concentration salt solution injected into the soil can significantly improve the electro-osmotic drainage effect, for there are no corrosion problems with the electrodes. The electroconductive filter cloth of the EVD does not have much impact on drainage effect and can be replaced by nonwoven fabric cloth. Suggestion is given in this paper that the operation way of electro-osmosis is to provide low energy for the soil in the early stage and then constantly improve the energy when the drainage rate is significantly reduced.     

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.     

Water content and shear strength evaluation of marine soil after electro-osmosis experiments

In this study, a series of electro-osmosis experiments were conducted using Dalian marine soil to evaluate the water content and shear strength of soil samples after electro-osmosis experimental treatment. The conditions that were considered in these experiments include voltage, preloading pressure, drainage direction, temperature, anode material, and processing duration. In comparing water content and shear strength, the different operational conditions were demonstrated to affect the results of electro-osmosis to a variable extent. For example, the shear strength of samples at 35°C improved by an average of 61.96% compared with room temperature samples. Also, water content under 12?V trials decreased by an average of 9.30% compared with 6?V. These results can be attributed to the difference in electro-dewatering capacities of the conditions mentioned above. Based on the data, two statistical relationships, which represent the relationship between experimental conditions and results, were also established.     

真空预压施工质量监理要点

做好真空预压施工的关键工序是：密封薄膜、双排粘土搅拌桩帷幕。首先,好的密封性能是形成较高真空度的基础,必须采取各种措施进行密封处理;施工中,保护密封膜,做好双排粘土搅拌桩帷幕施工,保证形成较高的膜下真空度,是真空预压施工质量监控的关键要点。同时,做好各项监测数据及时收集、记录,也是必要的研究参考依据。     

极限油套压差法在廖家场气藏泡排中的应用

泡沫排水采气现场施工参数主要涉及到不同气井的加注时机及加药量两项参数。加药时机过早,会增加施工成本,加药时机过晚,会影响泡沫排水效果;因此准确把握加药时机,是提高泡沫排水采气效果的关键。在比较准确地计算井筒积液量的基础上,通过分析历史生产数据,研究不同气井承受积液能力,根据气井的压差变化,采用极限油套压差变化来指导加药时机。     

Influence of vacuum pressure,pH, and potential gradient on the vacuum electro-osmosis dewatering of drinking water treatment sludge

This paper describes research that evaluated the influence of vacuum pressure, pH, and potential gradient on the vacuum electro-osmosis dewatering (VEOD) of drinking water treatment sludge (DWTS). In the first phase of the VEOD process, a vacuum pressure of ?0.05 MPa was applied alone to DWTS for 30 min, removing almost all free water and part of pore water. In phase two, electro-osmosis was applied in combination with intermittent vacuum filtration, further reducing pore water and surface adhesion water in DWTS. However, statistical analysis indicated that the optimum dewatering parameter values were vacuum pressure at ?0.06 MPa, pH at 6.2, and potential gradient at 2.5 V/cm, which resulted in a relevant energy consumption of 0.35 kW.h/kg removed water.     

金属/三元乙丙橡胶粘接工艺研究

研究了IN501胶粘剂的配比，烘干、抽真空工艺和M－25表面处理剂对金属／EPDM粘接性能的影响，对确定的最佳技术方法进行了重现性和加速老化试验，结果表明，IN501胶粘剂A／B的质量配比为5：3时，对金属表面用M-25处理，涂刷的胶粘剂的试件抽真空15min，可获得工艺和性能比较满意的效果。     

Effect of Ultrasound Pretreatment on Vacuum Drying of Chinese Catalpa Wood

Ultrasound pretreatment of wood prior to drying was examined as a method to increase the effective water diffusivity, reduce drying time, and improve product quality of Chinese Catalpa wood. Pretreatment tests were carried out at three pretreatment durations, three absolute pressure levels, and three ultrasonic intensities. All specimens were then dried at 60°C and the absolute pressure level of 0.02 MPa to determine the effects of pretreatment parameters on vacuum drying characteristics. A microscopic analysis was carried out to visualize the formation of microchannels and view any other changes to wood tissue structure that occurred. Results showed that ultrasound pretreatment prior to vacuum drying enhances the effective water diffusivity; the higher the ultrasound power level, the longer the pretreatment time, and the lower the absolute pressure, the shorter is the drying time. Ultrasound creates micro channels within the tissue of wood during pretreatment. However, the pretreatment time should not be too long when the ultrasound is high.     

软土地基排水板堆载联合预压数值模拟研究

采用有限差分法对排水板堆载联合预压固结过程进行了数值模拟,结合青岛某软基处理工程实例建立相关数值模型,利用平均固结度等效原则,将排水板单元转换为平面应变的砂墙地基进行计算,为真实模拟实际排水板堆载联合预压工程情况,考虑了排水板通水量变化对地基固结沉降的影响,在数值分析中引入变井阻模型,并将计算结果与现场实测值进行对比分析,验证了本模型计算的正确性,为相关的工程提供借鉴经验。     

真空排水系统在大型商业广场建筑中的应用

针对大型商业广场建筑中无法采用重力流排污水的场所,通过对传统和新型的排水方式的比较,介绍了真空排水系统在大型商业广场建筑中的实际应用,在使用频繁、有节水需要的场合,真空便器高效节水并实现真空同层排水易于满足特殊建筑个性化和私密性的高要求。     

分级加载电压下考虑有效电势变化的软黏土电渗固结理论

分级加载电压技术能够有效延长电渗处理的时间,改善地基的处理效果并能有效降低能耗。在利用分级加载电压技术开展电渗试验时,随着土体的排水固结,土体各点的电势会发生明显的变化,这与现有的电渗固结理论假设土体各点电势保持不变有所差异。利用自主设计的电渗试验仪器开展了分级加载电压下的电渗室内试验,分析了电渗过程中土体有效电势变化的规律。基于该规律并结合Esrig固结理论建立了在阳极处不排水、阴极处排水条件下考虑土体有效电势变化的电渗固结理论,得到了分级加载电压条件下考虑土体有效电势变化的超静孔隙水压力和平均固结度的解析表达式。研究表明,在电压分级加载过程中,土体有效电势变化规律表现为随时间先基本保持不变,后呈抛物线状先增后减。通过试验案例验证了考虑土体有效电势变化所求得解析解的合理性,且该数值计算结果相较于Esrig数值计算结果,前者更加接近实测值,该固结方程的建立为后续分级加载电压技术的推广应用提供了理论依据,也为实际工程提供了参考。     

Preloading Technique in Dynamic Fatigue Testing of Glass and Ceramics with an Indentation Flaw System

The solution of fatigue strength as a function of preloading in dynamic fatigue testing was obtained numerically for an indentation flaw system. The dynamic fatigue strength is dependent on preloading and fatigue parameter (K). The effect of preloading on dynamic fatigue strength decreases with increasing fatigue parameter: for n 20 the effect is negligible up to a preloading of 90%. The solution was verified by dynamic fatigue experiments conducted with soda-lime glass and alumina specimens with as-indented flaws in room-temperature distilled water. The result indicates that one can apply a preloading corresponding up to 90% of fatigue strength for most glass and ceramic materials with no change in fatigue strength, resulting in a dramatic saving of testing time.     

Dewatering of drinking water treatment sludge by vacuum electro-osmosis

The objective of this research was to evaluate the dewatering of drinking water treatment sludge (DWTS) by vacuum electro-osmosis dewatering (VEOD) technology. DWTS has a high moisture content, with the water existing as free water, pore water, surface adhesion water and internal combined water. Vacuum filtration of 0.05 MPa can quickly dewater sludge and has low energy consumption, but can only remove free water and some pore water. The moisture content of the DWTS was reduced to below 79% by vacuum filtration technique alone. At this moisture content, all free water had been expelled by vacuum filtration. Electro-osmosis optimized for the experimental conditions (0.05 MPa, 2.5 V/cm) began after vacuum filtration ceased, and drew pore water and surface adhesion water to the cathode, where it was expelled through vacuum filtration. The VEOD process removed all free water. In addition, pore water and surface adhesion water were reduced by 60.2% and 15.9%, respectively.     

乳胶粒子用附聚剂的制备及应用

采用丙烯酸(AA)、丙烯酸丁酯(BA)混合单体通过乳液聚合方法合成附聚剂,用于聚丁二烯胶乳(PBL)的附聚.研究了附聚时间、附聚剂组成、附聚剂加入量、附聚剂的粒子尺寸等因素对聚丁二烯(PB)胶乳粒径大小的影响.结果表明:附聚时间为40～60 min时,附聚过程基本完成;当BA/AA质量比为80/20时,附聚效果最好;附聚剂在PBL中加入量占PBL总质量的8.3％时,附聚效果明显;PBL平均粒径由原来的96nm附聚到了240～260 nm,粒径得到了明显的增长,合成的附聚剂有良好的附聚效果.     

An interlaboratory study of test methods

Conclusions Our aim has been to construct a simple method of scoring consistent with the objectives of the study and to present the results in a manner that does not require too much statistical sophistication. However, if realistic estimates of the precision of test methods are to be obtained, the interlaboratory tests must be more thoughtfully designed and the statistical analysis will tend to be somewhat more complicated as in the components of variance analysis we have presented.     

Sodium bisulphite as a stabilizer for hydrogenated cottonseed oil shortening

Hydrogenated, deodorized cottonseed oil shortening, may be given increased keeping time and lowered peroxide values, if treated with small amounts of NaHSO₃ (either the dry powder or a saturated solution). The flavor of the treated shortening will be good if not too much bisulphite is used. The shortening so treated will contain a very small amount of SO₂.     

Preliminary tests of an electrokinetic barrier to prevent heavy metal pollution of soils

Sardinia has to deal with significant environmental problems related to heavy-metal contamination, mainly located at its abandoned mining districts. In particular, acid mine drainage management and groundwater pollution are typical problems associated with mining activities which constitute a serious threat to human health. To prevent contaminant spread over the adjacent environment, it is of great interest to consider using an electric field as a containment fence to counteract pollutant transport. In this application, contaminant transport due to a hydraulic gradient driving force is prevented by the combined effect of electro-osmosis and electro-migration. Although there are other alternative containment technologies, the electrokinetic fence offers many advantages, as it is easy to operate, there is a minimal exposure to the operating personnel and it is likely to be effective for a wide range of contaminants. In this work, both one-dimensional (1D) and two-dimensional (2D) tests have been carried out. In the 1D tests, the efficiency of an electrokinetic barrier to prevent cadmium from polluting an uncontaminated sample was investigated; soil pH, metal concentration and current intensity have been monitored; results indicate that the barrier can prevent or significantly reduce heavy-metal contamination from spreading against a hydraulic gradient of 7. In 2D tests, two rows of electrodes inserted in a horizontally flat soil tank were used to generate an electric field. It was found that an electric field of 125 V m⁻¹ was sufficient to prevent significant copper incursion from a contaminant flow under a hydraulic gradient of 1.3.     

Liquid Phase Sintering of Alumina, III. Effect of Trapped Gases in Pores on Densification

The microstructure evolution and densification kinetics of alumina containing 10 and 20 vol% calcium aluminosilicate glass were studied, for sintering under vacuum and air at 1600°C. Residual porosity was always present in the air-fired samples. The kinetic analysis lent strong support to the notion that trapped gases inhibited the densification and limited the attainment of full density. The samples containing 20 vol% glass were able to reach full density during vacuum sintering. However, the samples containing 10 vol% glass contained some residual porosity even after vacuum sintering, which was attributed to the preferential volatalization of liquid phase.     

预缩聚反应器真空喷淋系统的化学清洗

预缩聚反应器的真空喷淋系统的工作介质是乙二醇 (EG)。运行一段时间后 ,预聚体沉积于板式换热器、喷嘴及引管等处 ,使抽真空能力下降直至丧失。此处的预聚体聚合度为 4,不溶于常温下的NaOH水溶液 ,也不溶于NaOH·EG溶液 ,却可溶于NaOH的水和EG的混合溶液。NaOH的水和EG的混合溶液不会腐蚀喷淋系统 ,也不会污染喷淋系统。利用该性质成功地在 110t/d的生产装置上进行在线化学清洗