乌鲁木齐机场戈壁砾石土填料的工程特性试验研究∗

以新疆乌鲁木齐机场改扩建工程中道基填筑拟采用的戈壁砾石土填料为研究对象,开展了戈壁砾石土的颗粒分析、表面振动压实、点荷载强度等物理力学试验,对其颗粒特征、压实特性以及大粒径砾石强度展开了探讨.结果 表明:该地区戈壁砾石土不均匀系数Cu为37.9,曲率系数Cc为2.12,属于级配良好的砾类土,且填料在1～2 mm粒组处存在一定程度的缺失;不同粗颗粒含量戈壁土均存在明显的最优含水率与最大干密度,最大干密度随含水率变化呈现抛物线形式,且随着填料粗颗粒含量的增加而增加;天然级配的戈壁砾石土粗颗粒含量超过70％,最大干密度可达2.41 g/cm3;另外,戈壁砾石土中大块砾石的强度较高,自然风干状态下单轴抗压强度的平均值约为60 MPa.试验得出乌鲁木齐机场建设采用的天然级配的戈壁砾石土是一种非常好的道基填筑材料,研究结果亦可为类似工程提供参考.     

MICP技术对遗址土开裂抑制作用的试验探究∗

遗址土长期经受干湿循环作用,土体表面产生的裂隙对其保存构成威胁。为了探究MICP技术在土遗址修缮中的应用,基于巴氏芽孢杆菌开展微生物矿化作用的前期研究,确定了微生物最佳培养时间、菌液的最佳菌胶比、最佳胶结液浓度和拌合菌液的最佳体积分数;利用最优条件的研究结果对遗址土干缩开裂抑制作用进行研究,设置纯水拌合的对照组,对比观察初次干湿循环下烘干过程中的裂隙发育情况,分析三次干湿循环后裂隙的二值化图像,对比裂隙率,证明了MICP技术对遗址土干缩开裂的有效抑制;结合电镜扫描图像,分析碳酸钙胶结物的作用机理。通过试验研究和电镜图像的拟合分析,证明MICP技术对减缓遗址土开裂具有积极作用,为土遗址的修缮和维护提供了新思路。     

高岭土对喹诺酮类抗生素吸附特性的初步研究

以高岭土为吸附剂进行2种喹诺酮类抗生素(诺氟沙星和环丙沙星)的静态吸附实验,考察平衡时间、初始浓度、pH值、阳离子种类与强度等对吸附性能的影响.结果表明,高岭土对诺氟沙星和环丙沙星的吸附过程均符合二级反应动力学方程,吸附速率常数分别为0.021 kg/(mg·h)和0.156 ks/(mg·h);诺氟沙星和环丙沙星可划...     

Probabilistic ecological risk assessment for three chlorophenols in surface waters of China

Individual and combined assessment of risks of adverse effects to aquatic ecosystems of three chlorophenols (CPs), including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), were conducted. A probabilistic approach based on the concentrations of CPs in surface waters of China was used to determine the likelihood of adverse effects. The potential risk of CPs in surface waters of China was determined to be of concern, especially PCP and mixtures of CPs. The risks of adverse effects were examined as the joint probabilities of exposure and response. The joint probability for PCP was 0.271 in the worst case and 0.111 in the median case, respectively. Based on the cumulative probability, 5% of aquatic organisms included in the assessment would be affected 21.36% of the time in the worst case and 5.99% of the time in median case, respectively. For the mixtures of CPs, the joint probability were 0.171 in the worst case and 0.503 in median case, respectively and 5% of species would be affected 49.83% of the time for the worst case and 12.72% in the median case, respectively. Risks of effects of the individual CPs, 2,4-DCP and 2,4,6-TCP were deemed to be acceptable with a overlapping probability of < 0.1 with 5% of species being affected less than 4% of the time.     

pH modeling for maximum dissolved organic matter removal by enhanced coagulation

Correlations between raw water characteristics and pH after enhanced coagulation to maximize dissolved organic matter (DOM) removal using four typical coagulants (FeCl₃, Al₂(SO₄)₃, polyaluminum chloride (PACl) and high performance polyaluminum chloride (HPAC)) without pH control were investigated. These correlations were analyzed on the basis of the raw water quality and the chemical and physical fractionations of DOM of thirteen Chinese source waters over three seasons. It was found that the final pH after enhanced coagulation for each of the four coagulants was influenced by the content of removable DOM (i.e. hydrophobic and higher apparent molecular weight (AMW) DOM), the alkalinity and the initial pH of raw water. A set of feed-forward semi-empirical models relating the final pH after enhanced coagulation for each of the four coagulants with the raw water characteristics were developed and optimized based on correlation analysis. The established models were preliminarily validated for prediction purposes, and it was found that the deviation between the predicted data and actual data was low. This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.     

香港特区电梯事故管理机制研究

香港特区是典型的经济发达地区,电梯安全管理水平达到世界先进。通过学习香港电梯安全管理和事故管理经验,研究电梯的安全条例、守则中电梯各相关方的职责、电梯事故的管理机制,分析香港特区电梯典型的事故技术调查报告和历年的事故统计数据,有利于加强内地与香港特区之间的技术和管理方面的深入交流,有助于给出进一步提升国家电梯安全和应急管理水平的有效措施和建议。     

福美双对斑马鱼早期胚胎原始生殖细胞和形态发育的影响

福美双是一种二硫代甲氨基甲酸盐类农药,在我国有非常广泛的应用,但其高残留性受到广泛的重视。试验使用斑马鱼胚胎作为动物模型,探讨了福美双对生殖的毒性作用。结果表明福美双虽然没有引起原始生殖细胞表达量的变化,但造成原始生殖细胞移动分布的延迟,以及诱导细胞凋亡。试验表明福美双对胚胎发育以及生殖有显著的影响,进一步说明斑马鱼胚胎可作为农药毒性评价的模型。     

“十四运”期间西安PM2.5中水溶性无机离子污染特征

为探究中国第十四届运动会(简称“十四运”)期间西安大气PM_2.5中水溶性无机离子浓度水平及来源,利用高分辨率MARGA ADI 2080离子在线分析仪对西安“十四运”前、“十四运”期间和“十四运”后水溶性无机离子进行实时观测,分析了不同时段水溶性无机离子组分污染特征、pH变化及污染来源。结果表明,“十四运”前、“十四运”期间和“十四运”后PM_2.5质量浓度分别为13.4、11.9、32.6μg/m³,SNA(NO^-₃、SO₄^2-和NH⁺₄三者统称)质量浓度分别为5.8、5.4、13.3μg/m³,占总水溶性无机离子的91.6%～93.6%。“十四运”前和“十四运”期间NO^-₃与SO₄^2-质量浓度比分别为0.7和0.9,表明移动源的比例增加,主要受交通管控的影响。“十四运”后NO     

格栅纵/横肋对筋-土界面拉拔特性的影响研究

为了研究格栅加筋土体复合材料的加筋机理,借助砂土中双向格栅的拉拔试验,综合研究了纵肋根数、纵肋长度、横肋数量和格栅裁剪方式等对筋?土界面作用特性和格栅横肋贡献率的影响。研究结果表明：无横肋时筋材拔出对应的极限拉拔力随纵肋根数增加近似呈线性增加,并随筋材单根纵肋长度的增加,筋材极限拉拔力对应的加载端位移增大;当筋材长度增加且大于临界长度时,摩擦阻力增量斜率降低;保持纵肋相同,增加横肋数量筋材极限拉拔力增加,且横肋端承阻力对拉拔力贡献率逐渐增加,受横肋位置影响横肋对筋材拉拔力贡献率的增幅逐渐降低;针对相同的 50% 横肋百分比,筋材裁剪方式对筋?土界面摩擦作用效果显著,格栅横、纵肋分布越均匀,格栅极限拉拔力越大,表明格栅网格均匀性是确保加筋效果的关键因素之一。