硅藻土地区桥梁灌注桩成孔测试研究∗

硅藻土作为一种特殊的黏性土,在分布上具有一定的区域性,目前针对该类型土的工程特性以及硅藻土地区灌注桩成孔方法的研究都较少。以杭绍台高铁项目为工程依托,为了研究硅藻土层中灌注桩的成孔方法,开展了灌注桩成孔方法现场试验;分别采用冲击锤锤击成孔、旋挖干钻成孔和旋挖泥浆护壁成孔三种方法进行施工,对三种方法的成孔质量进行分析对比。研究结果表明:在硅藻土地区施工灌注桩,旋挖干钻成孔工艺施工速度较快,效率高,桩长、桩径、桩位偏差和垂直度均能满足设计要求,成孔后孔壁稳定性好,成孔质量更为可靠;冲击锤法成孔,成孔速度较慢,且存在桩孔扩径现象;旋挖泥浆护壁法成孔后平稳性较差,波动性较大,且存在局部塌孔现象,成孔效果较差。因此建议硅藻土地段优先考虑采用旋挖干钻法施工桥梁灌注桩。     

盾构施工引起周围土体位移的数值研究

盾构隧道施工会引起周围地层及地表变形并影响周围环境,为探索变形规律以进行预测,运用岩土数值软件FLAC3D建立三维模型,考虑天津地区软土特性,注浆体材料强度的时空变化特性及盾构施工中的各相关作用进行研究。首先建立标准模型进行分析,并与Loganathan公式计算及工程实测数据计算进行对比验证,然后就重要施工参数如超挖孔隙、注浆压力等的影响,不同土体本构关系对计算结果的影响,土体修正剑桥模型参数如超固结比、内摩擦角、压缩参数λ及回弹参数κ的影响进行了研究,将结果与已有的研究结果进行比较,具有较好的一致性。     

Thermal and Mechanical Properties of Polyurethane Rigid Foam Based on Epoxidized Soybean Oil

A soypolyol based on epoxidized soybean oil (ESO) was prepared in the presence of HBF₄ and diethanolamine (DEA) was used as ring opener. A series of polyurethane rigid foam were prepared by mixing polyol with TDI using an isocyanate index of 1.1. The polyol used in this paper were a mixture of soypolyol and a commercial PL-5601 polyester polyol and the mass fraction of PL-5601 was in the range of 0–60%. The thermal properties of the resins were characterized by DSC and TG. The results showed that these rigid foams possess high thermal stability. There were two glass transition temperature of each foam and Tg₁ was increasing with the increasing of OH value. The compression strength of the foam was also recorded, and the effect of mass ratio of soypolyol and PL-5601 polyester polyol on the compression strength was discussed.     

Metal removal with two biochars made from municipal organic waste: adsorptive characterization and surface complexation modeling

The adsorptive characteristics of biochar produced from garden green waste (S-char) and a mixture of food waste and garden green waste (FS-char) were investigated. Adsorption of Cu²⁺, Zn²⁺, and Mn²⁺ onto the two biochars reached equilibrium within 48 hours. The metal adsorption was effectively described by the pseudo-second-order kinetic and Freundlich isotherm models which suggest heterogeneous chemisorption. The initial solution pH influenced adsorption of Zn²⁺ and Mn²⁺ but not of Cu²⁺. Simulation via a surface complexation model showed that the fraction of XOCu⁺ adsorbed onto biochar was increased with increasing pH until it reached the adsorption maximum at pH 8.5, while the endpoint for the maximum of XOMn⁺ was higher than pH 12.     

The effect of limiting nutrient on metal toxicity to selenastrum capricornutum

Metal toxicity on selenastrum capricornutum were examined by batch culture and chemostat culture system. EC₅₀ values under nutrient‐limited condition and saturated condition were compared. The two EC_5Os differed by a factor of 10.6 for Cd in batch test, and differed by a factor of 6.5 in continuous test. Both batch and continuous test results indicate that inhibition on algal growth is more severe under nutrient‐limited conditions compared to that under near saturation conditions.

Strong correlation, as characterized by the correlation coefficient ρ, were found between the activation level (nutrient requirement) and the tolerance of microorganisms to the toxicant. ρ is equal to 0.9 for the case of Cd in batch test and 0.6 in continuous test. The theory in this study provides generally good estimations to the dose‐response relationship at limiting nutrient conditions. The study indicate that nutrient conditions constitute an important factor in algal toxicity tests.     

Essential and nonessential elements in the red-crowned crane Grus japonensis of Zhalong Wetland,northeastern China

The concentrations of four essential (Ca, Mg, Zn, and Cu) and two nonessential elements (Pb and Cd) in feathers and kidneys, livers, gut walls, and muscles of eight carcasses of migratory red-crowned cranes (Grus japonensis) from Zhalong Wetland, northeastern China, were examined. The concentrations of Cd in the feathers were between 0.4 mg kg^?1 dry weight (dw) and 3.1 mg kg^?1 dw, in the livers between 0.4 and 4.4 mg kg^?1 dw, the maximum of which exceeded a level considered to be environmental exposure risk (i.e., 3 mg kg^?1 dw in the liver or kidney). High Pb levels (0.4–3.2 mg kg^?1 dw, with an average of 1.8 mg kg^?1) were also detected in livers, which exceeded a level considered toxicosis in birds (1.7 mg kg^?1 dw). Pb and Cd had the highest scores in principal component analysis. Relatively high Pb and Cd concentrations in the migratory cranes were thought to be associated with their habitat and prey.     

太原市工、商业区PM10中PAHs碳同位素组成及来源

利用中流量大气综合采样仪采集太原市工业区和商业区PM₁₀样品,使用GC/IRMS技术分析了PAHs的δ13C值(碳同位素组成),并根据碳同位素质量平衡计算了煤烟尘和机动车尾气对2类功能区的贡献率. 结果表明:工业区PM₁₀中PAHs的δ13C值在-26.0‰~-24.5‰之间,随环数增加呈贫13C趋势,与煤烟尘δ13C值的变化趋势一致,表明煤烟尘是工业区的一个主要污染源;商业区PAHs的δ13C值在-26.6‰~-26.2‰之间,较工业区显著贫13C,商业区与工业区的污染源有明显差异;除机动车尾气和煤烟尘外,工业区和商业区还有其他污染源输入,其中工业区有生物质燃烧排放输入,商业区有机动车曲轴箱润滑油残渣输入;煤烟尘和生物质燃烧对工业区的贡献率分别为59.3%~70.8%和29.2%~40.7%,表明工业区煤烟污染严重;机动车对商业区PAHs的贡献率在86.1%~95.8%之间,是商业区PM₁₀中PAHs的主要排放源,其中润滑油残渣的贡献率(在40.9%~85.3%之间)最大,机动车尾气的贡献率在8.3%~54.9%范围内,而煤烟尘的贡献率(在4.2%~13.9%之间)最小.      

秸秆-污泥复合基活性炭的制备及其对1,2,4-酸氧体的吸附特性

以污水处理厂剩余污泥与芦苇秸秆为原料,采用化学活化和高温热解的方法制备了秸秆-污泥复合基活性炭,研究了其各项性质及对1,2-重氮氧基萘-4-磺酸(1,2,4-酸氧体)的吸附性能.结果显示,当污泥与秸秆的质量比为4∶1时,经0.5 mol.L-1的KOH活化并且600℃高温炭化后,复合基活性炭的比表面积和含碳量分别为558.1 m.2g-1和58.9%,比污泥基活性炭提高了9.2%和4.6%,掺杂秸秆能有效提高污泥制备活性炭的比表面积和含碳量;扫描电镜观察显示,复合基活性炭表面呈多孔状.热分析研究发现复合基活性炭前躯体的高温热解过程主要伴随低温区域的脱水以及高温区域的造孔,其800℃热解时的烧失率为43%;N2吸附脱附曲线表明添加秸秆有利于增加活性炭微孔及中孔数量;在25℃下对酸氧体的吸附等温线结果显示,经秸秆掺杂的复合基活性炭其吸附性能明显提高,最大吸附量为56.4 mg.g-1,而同等条件下污泥基活性炭的最大吸附量仅为20.4 mg.g-1,表明复合基活性炭对该染料具有较好的吸附性能.从而本研究也为更好地实现污泥的资源化利用提供了一条有效途径.     

复合矿物吸附剂处理模拟含油废水性能研究

采用共混合法制备复合矿物吸附剂,通过矿物粉末对模拟含油废水COD的去除效果及复合矿物吸附剂质量散失率确定其组分的最佳配比。考察了吸附时间、振荡速率、废水pH、吸附剂用量等因素对模拟含油废水COD去除效果的影响。结果表明:制备复合矿物吸附剂最佳焙烧温度为600℃,最佳焙烧时间3 h,对模拟含油废水中COD的去除率可达90%以上。     

Polychlorinated dibenzo p-dioxins and dibenzofurans emissions in a primary copper smelter in China

Metallurgical production is the largest polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) emission source in China. However, PCDD/F monitoring and research are rarely conducted on primary metallurgical production. In this study, a demonstration primary copper smelter in China was selected to investigate PCDD/F characteristics and control. Samples were collected from major PCDD/F release points in the smelter process (fly ashes and waste water sludge). Specific analysis of PCDD/F congeners was carried out using a high resolution gas chromatography/high resolution mass spectrometry method. The results showed that PCDD/Fs might be unintentionally produced in the primary copper smelter processes, with sample concentrations of 180–6110 pg/g dry wt; highly chlorinated PCDD/F homologues were predominant. The toxicity of all the samples was calculated to be 120 pg WHO TEQ/g, fly ashes from the refining process furnaces air pollution control device and sludge were hazardous waste with higher PCDD/F toxicity. Both precursor formation and de novo synthesis were found to contribute to PCDD/F formation in the smelter process. PCDD/F characteristics and formation were compared with reported secondary copper smelters. Life-cycle control of PCDD/F was proposed for retrofitting of this smelter and for similar plants in China's primary copper production sector, including control at the PCDD/F formation, removal and disposal stages.