钢管代替钢筋土钉杆体在粉砂及松填土层基坑土钉支护中的运用

在粉砂层和松填土层等土层进行土钉施工,存在成孔时孔壁稳定性差的问题。影响了土钉的运用,本文主要从改变土钉杆体出发,用工程实例介绍在粉砂层和松填土层等成孔困难的土层土钉的运用技术。     

填土层对基坑支护的影响研究

基坑的开挖与支护设计经常要涉及到填土层,而填土层复杂的工程性质不可避免的带来了诸多问题。文章通过对若干基坑破坏的实例分析,介绍了基坑填土层对支护的影响,为相似的基坑设计参数处理和施工提供类似案例参考。     

土层变化对湿喷桩成桩质量影响的试验研究

通过一系列原位试验和室内试验,研究了土层变化对湿喷桩成桩质量的影响。结果表明:土层变化影响区内湿喷桩强度仅为单一土层的30%~50%;由亚粘土层过渡到淤泥质(亚)粘土层的地基,土层变化影响区宽约1.6m,上覆土层中占1.2m,下伏土层占0.4m,呈不对称分布;该影响区域内,上覆土层对湿喷桩早期强度的影响大于下伏土层,且在上覆层中湿喷桩强度降至最低,其下降量达63%~68%,在接近土层分界面桩身强度开始增大,当到达影响区底面时,强度增大67%~100%,随之趋于稳定。     

液化对房屋震害影响的宏观分析

本文从液化土层具有双重作用的观点出发,研究其对多层砖房震害的影响;利用震害指数增量值来判断液化土层的作用;指出液化层厚度、覆盖层厚度及刚度等在液化土层对震害的影响中具有重要作用;给出了可不考虑液化层作用的初判条件,可供工程设计时应用。     

软土路基稳定性影响因素分析

采用路基稳定性分析的Bishop法,模拟分析了软土路基中一侧临空的路基、高水位一侧临空的路基,高路堤一侧临空的路基三种模式下,填土层和天然软土层的强度参数内聚力、内摩擦角变化及填土容重变化、下卧层厚度变化对路基稳定性的影响机制.结果表明,在这三种模式下路基的稳定性随着填土层或软土层内聚力和内摩擦角的增大而增加,随着填土客重的增大而减小;在一定厚度范围内,随下卧层厚度增大而减小;高水位和高路堤都在一定程度上降低了路基的稳定性.同时发现,同一土层中内聚力和内摩擦角的相对影响程度取决于该层在整个路基稳定性影响深度范围中所占的比例,不同土层受内聚力和内摩擦角的影响程度也与该层在整个路基稳定性影响深度范围中所占的比例有关.     

填土地基上阶梯状条形基础的简捷计算法

<正> 在填土地基上常选用条形基础。为防止由于填土层厚薄不一引起的不均匀沉陷导致上部结构产生较大的附加应力,基础的埋深应根据填土层厚度的变化而变化,使条形基础成为阶梯状。又因填土层属于高压缩性软弱地基,其密实度较之下部的硬土层要小许多,按弹性地基理论,此填土层可视为局部变形弹性体。因此,填土地基上的条形基础按局部变形弹性体上的阶形梁进行分析是适宜的。本文用里兹(Ritz)位移变分法对其分析,较目前诸如链杆法、截面法以及分段初参数法简便实用,更宜于在袖     

长沙市某医院深厚填土层边坡治理研究

长沙市某医院项目工程场地为渣土消纳场,均为深厚填土层,场地整平后将在场地四周形成高3～16 m的填方边坡。采用“放坡+格宾挡墙”边坡支护形式,有效解决短期内完成3～16 m的深厚填土层边坡治理难题。经过对边坡水平位移及沉降监测,在一个月以后逐步趋于稳定,水平位移及沉降的变形速率和变形累计值均未超过设计预警值。     

多桥静力触探在临海深厚层超软土地区工程勘察中的应用与展望

临海深厚层超软土工程性质的评价一直是工程界的难点之一,文章总结了静力触探在深厚软土层场地勘察中的优势,并基于某临海深厚层超软土地区的勘察项目,运用了可量测倾斜度的多桥静力触探设备;验证了多桥静力触探可准确区分填土层与淤泥质土层;建立了本场地淤泥质土层的q_c、f_s与不同试验条件下抗剪强度的换算关系式;通过类比淤泥质土层的换算关系,得到了吹填填土层更为合理的剪切强度指标建议值。结合静力触探的优势,下一步研究方向之一可放在其替代标准贯入试验作为花岗岩残积土工程性质的判别手段。     

在液化土层中的深基坑支护技术及有关问题探讨

在闹市区液化饱和软土层这一特定的环境中施工,其基坑支护结构方案选择的正确与否,对整个基础工程施工安全顺利进行有着重要的意义。本文仅以上海市区该土层基坑施工实例,阐述了采用钻孔灌注桩、树根桩、深层搅拌桩以及地下连续墙作为支护结构的一些经验与教训,供工程界同仁参考。 1 液化土层情况的大致描述 1.1 第一层土——素、杂填土。土层厚度一般0.5m～1.3m。结构松散。 1.2 第二层土——褐黄～灰色粉质粘土。土层厚度一般为0.5m～1.5m,渗透系数较小。     

旋挖桩在基础施工中的应用及质量控制

1概述旋挖钻孔灌注桩是利用钻杆和钻斗的旋转及重力使土屑进入钻斗,土屑装满钻斗后,提升钻斗出土,这样通过钻斗的旋转、削土、提升和出土,多次反复而成孔。该工法适用于填土层、粘土层、粉土层、淤泥层、砂石层     

冻融对固化钻井泥浆强度及重金属浸出量影响

在石油钻井过程中会产生大量含重金属废弃钻井泥浆,对环境污染很大,需进行无害化处理。本研究采用水泥和工业废渣固化废弃钻井泥浆,经过不同次数的冻融循环后,测试固化土强度、固化土中Pb²⁺离子和Cr⁶⁺离子的浸出量以及固化土中的孔隙变化规律,探讨工业废渣固化废弃钻井泥浆的抗冻性能。结果表明:固化土试件的强度均随着冻融循环次数的增加而下降;固化剂组分中工业废渣的掺量增加,特别是磷石膏掺量增加能够有效的减弱固化土在冻融循环作用下的强度损失。工业废渣能够有效的稳定固化土中的Pb²⁺离子和Cr⁶⁺离子,浸出量比水泥固化土降低70%~80%。对固化土孔隙的测试结果证实由工业废渣固化的固化土试件的密实度大于仅由水泥固化的试件。     

The effect of natural water conditions on the anti-bacterial performance and stability of silver nanoparticles capped with different polymers

This study evaluated the effect of natural water composition onto the bactericidal and physicochemical properties of silver nanoparticles (AgNPs) stabilized with three different polymeric compounds.All the nanoparticles behaved similarly in the water conditions tested. Compared to solutions with low organic matter content and monovalent ions, lower disinfection performances of AgNPs suspensions were obtained in the following order seawater ≤ high organic matter content water ≤ high divalent cations content synthetic water. Suspension of AgNPs in seawater and water with divalent cations (Ca²⁺ and Mg²⁺) formed larger AgNPs aggregates (less than 1400 nm) compared to other solutions tested (up to approximately 38 nm). The critical coagulation concentration (CCC) of AgNPs was determined to quantitatively evaluate the stability of the nanoparticle suspension in different water conditions. When the concentration of dissolved organic matter was increased from 0 mg/L to 5 mg/L, the CCC increased by a factor in the range of 2.19 ± 0.25 for all AgNPs in divalent solutions, but a smaller increase occurred, in the range of 1.54 ± 0.21 fold, when monovalent solutions were used.The concentration of ionic silver released indicated that the dissolved Ag⁺ (3.6-48.2 ppb) was less than 0.5% of the total mass of Ag⁰ added. At all the conditions tested, the concentration of silver ions in solution had a negligible contribution to the overall anti-bacterial performance of AgNPs.This study demonstrated that the anti-bacterial performance of AgNPs at selected natural water conditions decreases in the presence of dissolved natural organic matter or divalent ions, such as humic acid and calcium carbonate. These results may be helpful in understanding the toxicity of AgNP in various natural water conditions and in explaining the risk associated with discharging AgNP in natural aquatic systems.     

Uptake of metal ions by chemically treated human hair

The uptake capacity of chemically treated human hair waste for the various metal ions can be arranged in the following decreasing order: Hg²⁺ (Hg⁺), Ag⁺, Pb²⁺, Cd²⁺, Cu²⁺ (Cu⁺), Cr⁶⁺, Ni²⁺, Cr³⁺.The uptake capacity is significantly affected by the presence of other metal ions. Anionic effect was found to be more pronounced for a mixed ions system than for a single ion system.     

Sorption of cadmium(II) and zinc(II) ions from aqueous solutions by cassava waste biomass (Manihot sculenta Cranz)

The sorption of two divalent metal ions, Cd(II) and Zn(II), onto untreated and differentially acid-treated cassava waste biomass over a wide range of reaction conditions was studied at 30°C. The metal ion removal from the spent biomass was also measured. The batch experiments show that pH 4.5–5.5 was the best range for the sorption of the metal ions for untreated and acid-treated biomass. Time-dependent experiments for the metal ions showed that for the two metals examined, binding to the cassava waste biomass was rapid and occurred within 30 min and completed within 1 h. High sorption capacities were observed for the two metals. The binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 86.68 mg/g Cd, 55.82 mg/g Zn and 647.48 mg/g Cd, 559.74 mg/g Zn for untreated and acid-treated biomass, respectively. It was further found that the rate of sorption was particle-diffusion controlled, and the sorption rate coefficients were determined to be 2.30×10⁻¹ min⁻¹ (Cd²⁺), 4.0×10⁻³ min⁻¹ (Zn²⁺) and 1.09×10⁻¹ min⁻¹ (Cd²⁺), 3.67×10⁻² min⁻¹ (Zn²⁺) for 0.5 and 1.00 M differential acid treatment, respectively. Desorption studies showed that acid treatment inhibited effective recovery of metal ions already bound to the biomass as a result of stronger sulfhydryl-metal bonds formed. Less than 25% of both metals were desorbed as concentration of acid treating reagent increases. However, over 60% Cd and 40% Zn were recovered from untreated biomass during the desorption study. The results from these studies indicated that both untreated and acid-treated cassava waste biomass could be employed in the removal of toxic and valuable metals from industrial effluents.     

Recovery of ammonia from industrial waste water

Some types of industrial waste water contain high concentration of ammonia, which makes nitrification too costly. It has been found, that ion exchange is an attractive alternative, even the waste water contains such high concentration of competitive ions at 1 g 1⁻¹ Ca²⁺ and 5 g 1⁻¹ Na⁺. However it was found, that the pH increased during the treatment due to the release of OH^- ions left in the interstitial water. Since it is essential for the efficiency that pH is 7·0 or lower, it was necessary to rinse the ion exchangers with acid. The observed data by column experiments agree with the equilibrium data found.     

Ulva prolifera (Chlorophyta): a suitable material to remove Cd2+ from aquatic environments

Heavy metal pollution in aquatic environments is a significant environmental problem. Marine macroalgae are novel materials for the removal of heavy metals from water, aided by their large biomass and the feature of easy collection. In this study, Ulva prolifera O.F.Müller was used to remove cadmium ions (Cd²⁺) from the aquatic environment. We examined the Cd²⁺ absorption capacity of the thalli in a factorial experiment using fresh thalli cultivated in seawater, freshwater, water containing domestic garbage, water containing industrial waste and elutriant of soil with additional Cd²⁺. In addition, changes in photosynthetic activity of thalli were investigated. A significant decrease of maximum quantum yield and effective photochemical quantum yield of PSII (YII) indicated Cd²⁺ was transported into the cells and seriously inhibited photosynthesis. Furthermore, the Cd²⁺ absorption capacity was relatively high. The results indicated the suitability of U. prolifera for removing Cd²⁺ from aquatic environments of different backgrounds.     

Studies on the use of inorganic gels in the removal of heavy metals

Chromium ferrocyanide gel shows a great affinity for Ag⁺, Cu²⁺, Tl⁺, Zn²⁺, Co²⁺, Cd²⁺, Mn²⁺ and Fe³⁺ and has been used to separate and recover some heavy metal ions viz. Tl⁺, Hg²⁺, Mg²⁺, Fe³⁺ etc. Some of these can be completely eluted from the columns of this exchanger material and the compound can be used to treat waste water rich in heavy metal ions.     

Synthesis,characterisation and application of new tamarind triethylamine (TTEA) resin for removal of toxic metal ions from the effluent of Puneet Steel Industry,Jodhpur, Rajasthan

A new ion exchange resin tamarind triethylamine (TTEA) was chemically synthesised by modified Porath's method of functionalisation of polysaccharides. The prepared resin was characterised on the basis of ion exchange capacity, elemental analysis, Fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA). Chemical resistivity of TTEA resin was assessed in several acidic, basic media. The present method is simple and rapidly applicable for the removal and recovery of metal ions from effluent of industries. The distribution coefficient (K _d) values of metal ions have been determined by batch method. Owing to the large differences in K _d values of toxic metal ions at different pH, removal and recovery of metal ions from their aqueous solutions and effluent of Puneet Steel Industry, Jodhpur has been studied systematically. The adsorption of different metal ions on TTEA resin follows the order; Fe²⁺ > Zn²⁺ > Cu²⁺ > Pb²⁺ > Cd²⁺. The Ion exchange capacity (IEC) of TTEA resin was 2.04%.     

土壤—膨润土对金属离子的阻滞性能及机理研究

以K⁺、Ca²⁺和Fe³⁺为研究对象,考察屏障材料Soil-Bentonite (SB)对不同价态金属离子的阻截性能,并对其吸附机理、运移规律和穿透行为进行探讨,为污染场地封存材料设计提供理论依据。研究结果表明:屏障材料SB对不同价态的金属离子的吸附过程快速,且离子价态越高吸附量越大;吸附过程的拟合符合二级吸附动力学和Langmuir-Freundlich方程。K⁺、Ca²⁺和Fe³⁺在SB中渗透时,渗透系数存在极值,离子价态越高则出现极值的时间越短;各种离子在屏障材料中穿透时,离子价态越高,完全穿透屏障墙体所需时间就越短。因此,在污染场地阻截封存时,高价态金属离子的存在会严重影响屏障材料对污染物的阻截性能。     

Malathion exposed seeds of Vigna Sinensis

Plasma membrane bound ATPase of Vigna sinensis (L) is activated by Mg⁺² and is further stimulated by monovalent cations like Na⁺/K⁺, at a definite pH and substrate concentration. The true substrate for the enzyme was Mg⁺⁺‐ATP. Ca⁺⁺ cannot replace Mg⁺⁺ so far as the activation of this enzyme is concerned. Activation does not alter much when treated with ouabain. These results support the concept that cation transport at the plasma membrane of root cells of Vigna sinensis (L) is coupled to a cation‐activated ATPase. Malathion (O, O‐dimethyl phosphorodithioate of diethyl mercapto succinate), an organo phosphorus insecticide, activates these enzymes at a concentration of 400 ppm. This increase in activity may be associated with some alteration in the membrane structure, and stimulation by malathion has been found to be of non‐competitive in nature when the divalent and monovalent ions are included in the system.