Rapid decolorization of Acid Orange II aqueous solution by amorphous zero-valent iron

Some problems including low treatment capacity, agglomeration and clogging phenomena, and short working life, limit the application of pre-treatment methods involving zero-valent iron (ZVI). In this article, ZVI was frozen in an amorphous state through a melt-spinning technique, and the decolorization effect of amorphous ZVI on Acid Orange II solution was investigated under varied conditions of experimental variables such as reaction temperature, ribbon dosage, and initial pH. Batch experiments suggested that the decolorization rate was enhanced with the increase of reaction temperature and ribbon dosage, but decreased with increasing initial solution pH. Kinetic analyses indicated that the decolorization process followed a first order exponential kinetic model, and the surface-normalized decolorization rate could reach 2.09 L/(m². min) at room temperature, which was about ten times larger than any previously reported under similar conditions. Recycling experiments also proved that the ribbons could be reused at least four times without obvious decay of decolorization rate and efficiency. This study suggests a tremendous application potential for amorphous ZVI in remediation of groundwater or wastewater contaminated with azo dyes.     

圆环巴西试验的抗拉强度建议公式

目的改进Hobbs公式得到的计算值普遍较大这一问题,提出圆环巴西试验的抗拉强度建议公式。方法对巴西试验圆环的应力解进行分析,并引用砂岩的试验数据验证。结果得到圆环巴西试验的抗拉强度建议公式,使用Hobbs公式得到的抗拉强度σTT比巴西圆盘试验σT大6倍以上,利用建议公式得到的抗拉强度σθ与巴西圆盘试验σT十分接近,误差不到1%。结论当圆环内外径比ρ在0.05到0.15的范围内时,该建议公式可很好地用来计算岩石类等脆性材料的抗拉强度。     

某场地边坡稳定分析方法的比较研究*

为了对边坡稳定性分析方法进行研究,以某场地高填方边坡和直立边坡为研究对象,基于Geostudio、理正软件以及ANSYS软件,采用M-P法、Bishop法和强度折减法进行边坡稳定分析。结果表明:高填方边坡安全系数为1.3,为稳定边坡;AB,BC,CD段地块间边坡边坡安全系数依次为0.479,0.410,0.381,基坑边坡安全系数为0.436,均为不稳定边坡;其中,M-P法得到的安全系数偏保守,Bishop法得到的安全系数结果较可靠,强度折减法得到的结果最为理想。研究结果可为边坡稳定性研究与治理提供借鉴。     

RBF神经网络可靠度分析方法在边坡稳定性研究中的应用

针对边坡稳定性可靠度分析,当状态函数无法显式表达且传统计算方法求解复杂问题困难时,提出一种基于ABAQUS和粒子群优化径向基函数神经网络的可靠度分析方法。基于ABAQUS的强度折减方法计算所选随机变量对应的安全系数,利用径向基函数神经网络的数据拟合功能,建立模型并映射出安全系数和随机变量之间的关系,构造响应面功能函数;利用蒙特卡罗生成的大量随机样本代入功能函数得到相应的安全系数,进而计算边坡的失稳概率和可靠度指标来反映边坡稳定性。研究结果表明:相对于传统方法,本文方法计算效率更高、误差更小,适合实际工程应用。     

基于不同强度等级混凝土的动力学特性研究

基于TAW-2000D电液伺服岩石三轴仪和直径75 mm的霍普金森压杆试验装置,得到了C25,C35和C45混凝土在静、动载荷作用下的应力-应变曲线,探讨了混凝土强度等级、动态峰值强度、峰值应变和应变率之间的变化规律。结果表明:混凝土准静态应力-应变曲线和动态应力-应变曲线在形态上存在明显差异,动态应力-应变曲线的峰值点随应变率的增大向右上方移动,线弹性阶段各曲线斜率变化不明显;动态峰值应力、动态弹性模量和峰值应变均存在不同程度的率相关性,并且混凝土材料的应变率敏感性随其强度等级的提高而增强;混凝土C45的各力学指标对应变率的敏感性最强,C35次之,C25的应变率敏感性最弱;推导了应变率与强度等级和冲击速率之间的经验公式,三者之间存在非线性变化规律。     

加卸荷条件下岩石力学特性与声发射特征

为了探究真三轴复杂应力变化条件下岩石强度及破坏模式,通过真三轴卸荷扰动测试系统对砂岩试件进行不同第二主应力加卸荷试验,讨论在加卸荷过程中岩石的力学特性及声发射特征。试验结果表明:第二主应力的增加对试件的承载能力起到先增强后弱化的效果;不同第二主应力加卸荷声发射能量及累计振铃计数变化趋势大体一致,耗散能量比在载荷达到岩石损伤强度时突增;声发射能量峰值提前于试件轴向应力跌落,声发射能量和累计振铃计数大幅突增可作为岩石破坏的前兆;在低载荷下岩石中活动主要是裂隙压密与发育,在达到岩石损伤强度后岩石中的活动主要是裂纹贯通形成破裂面,砂岩试件声发射定位点集中区域与试件主要破裂面基本吻合。     

爆破荷载作用下隧道中隔岩稳定性研究

为研究爆破动力荷载作用下隧道中隔岩稳定性评价标准,以福州地铁2号线为工程背景,结合强度折减动力分析法和数值模拟,同时考虑中隔岩塑性区贯通、位移超过规范值、计算不收敛3种判据,综合对隧道中隔岩进行动力安全系数分析,研究隧道不同净距、不同开挖进尺后行洞隧道爆破开挖对隧道整体安全系数的影响。研究结果表明:中隔岩塑性区贯通时特征点位移和规范中位移限值较为接近,可共同作为评价中隔岩稳定性的最终评价标准;隧道净距越大、进尺越小,隧道整体安全系数越高;对围岩质量较差且净距小于1.6 m的双线隧道进行爆破开挖时,建议将爆破进尺控制在2 m以内。研究结果可为类似工程提供理论参考依据。     

Application of a coupled ecosystem-chemical equilibrium model, DayCent-Chem, to stream and soil chemistry in a Rocky Mountain watershed

Atmospheric deposition of sulfur and nitrogen species have the potential to acidify terrestrial and aquatic ecosystems, but nitrate and ammonium are also critical nutrients for plant and microbial productivity. Both the ecological response and the hydrochemical response to atmospheric deposition are of interest to regulatory and land management agencies. We developed a non-spatial biogeochemical model to simulate soil and surface water chemistry by linking the daily version of the CENTURY ecosystem model (DayCent) with a low temperature aqueous geochemical model, PHREEQC. The coupled model, DayCent-Chem, simulates the daily dynamics of plant production, soil organic matter, cation exchange, mineral weathering, elution, stream discharge, and solute concentrations in soil water and stream flow. By aerially weighting the contributions of separate bedrock/talus and tundra simulations, the model was able to replicate the measured seasonal and annual stream chemistry for most solutes for Andrews Creek in Loch Vale watershed, Rocky Mountain National Park. Simulated soil chemistry, net primary production, live biomass, and soil organic matter for forest and tundra matched well with measurements. This model is appropriate for accurately describing ecosystem and surface water chemical response to atmospheric deposition and climate change.     

碱矿渣胶凝材料固化重金属污泥的研究

主要原材料为高炉矿渣的碱矿渣胶凝材料(HAS)、掺3%沸石的HAS、掺5%沸石的HAS、水泥等4种固化材料被用来固化人工合成含铅、镉、铬等重金属的污泥。污泥固化体中污泥与固化材的掺和比例为4:1。实验结果表明,HAS固化剂对重金属污泥的固化效果要好于水泥,其污泥固化体的无侧限抗压强度高于水泥固化体,同时其固化体的重金属浸出量明显低于水泥。沸石的掺入使HAS固化体的重金属浸出量减小,且随着沸石掺加量的增大,HAS固化体的重金属浸出量相应的减少。     

煤矿井下气候参数和劳动强度对矿工生理参数影响的研究

对机械化采煤工作面的采煤机司机和支柱工的劳动心率和能量代谢进行了现场实测。就气候参数和劳动强度对作业人员的生理参数影响进行了模拟实验,取得一些实验研究成果。对改善劳动条件和作业环境,提高生产效率,保护井下矿工的身心健康与安全,提供了科学依据。