综放开采覆岩“两带”高度影响因素及预测模型研究*

为研究影响综放开采覆岩“两带”高度预测模型,采用理论分析与经验公式方法系统分析影响覆岩“两带”高度的因素,包括覆岩岩性、覆岩组合结构、煤层赋存状态、顶板控制方法、开采厚度、工作面走向长度与倾向长度、工作面推进速度、覆岩破坏残余变形;并将上述因素划分为采矿地质因素、顶板控制方法、采煤工作面三维尺寸设计参数、时间因素4类;基于此建立综放开采“两带”高度预测模型,并通过工程实例对比、现场实测等方法进行合理性验证。结果表明:芦沟矿与盛泰矿2个工作面的“两带”高度预测值均在实测值范围之内,说明得出的回归式预测效果较好,验证综放开采“两带”高度预测模型的合理性。     

三峡库区消落区水体-沉积物重金属迁移转化特征

结合三峡水库反季节调度模式,对消落区沉积物中Cu、Pb、Cd、Cr这4种重金属的存在形态及迁移转化特征进行研究.结果表明,不同重金属在消落区沉积物中形态分布各异,Cu主要以有机物及硫化物结合态和残渣态形式存在,Pb主要以碳酸盐结合态、Fe-Mn氧化物结合态及残渣态存在,Cd主要以碳酸盐结合态、Fe-Mn氧化物结合态存在,Cr主要以残渣态存在.伴随着消落过程的进行,汛期出露沉积物的有机质及AVS含量下降、ORP升高、pH值降低,沉积物中可提取态重金属的相对含量显著下降,重金属具有向水体迁移趋势, Cu、Pb、Cd、Cr平均迁移率分别为30.50%、 26.10%、 33.50%和11.77%,4种重金属的迁移性大小依次为Cd>Cu>Pb>Cr.可提取态Cu、Pb、Cd、Cr对重金属迁移贡献率分别为77.15%、 86.09%、 94.86%和32.34%,可提取态是重金属发生迁移的主要部分.研究结果表明, 消落区重金属迁移呈"缓释"特征,三峡水库的反季节调度模式有利于缓解消落区重金属迁移诱导的生态风险,库区水体重金属含量处于较低水平.     

Electrokinetic movement of multiple chlorobenzenes in contaminated soils in the presence of β-cyclodextrin

This study investigated the electrokinetic (EK) behavior of multiple chlorobenzenes, including 1,2,3,4-tetrachlorobenzene (TeCB), 1,2,4,5-tetrachlorobenzene (i-TeCB), and 1,2,3-trichlorobenzene (TCB) in contaminated clayed soils. The effect of β-cyclodextrin (β-CD) on the EK removal of the chlorobenzenes was studied. The largest removal was obtained when Na2CO3/NaHCO3 buffer was used as anodic purging solution without β-CD. The removal efficiencies were related to the aqueous solubilities of chlorobenzenes. With the same cumulative electroosmotic flow, greater solubility led to higher removal efficiency. The addition of β-CD inhibited the EK removal efficiency of all chlorobenzenes. The inhibition increased with the increase of β-CD concentration. With the same β-CD concentration, the inhibition increased with the rise of electric potential. It was found that the inclusion compounds between β-CD and chlorobenzenzes were less soluble than chlorobenzenes. The formation of the less soluble inclusion compounds reduced the aqueous solubility of chlorobenzenes and led to the partial immobilization of the chlorobenzenes that desorbed from soil. It was feasible to use the EK technology to remove chlorobenzenes in contaminated soils using water as the anodic flushing solution. The addition of β-CD was not recommended for the EK removal of chlorobenzenes.     

Minimization of methabenzthiazuron residues in leaching water using amended soils and photocatalytic treatment with TiO2 and ZnO

In the present work, potential groundwater pollution by methabenzthiazuron （MTBU） and the effect of three different amendments （composted sheep manure, composted pine bark and spent coffee grounds） on its mobility were investigated under laboratory conditions. The efficiency of ZnO and TiO2 suspensions in the photocatalytic degradation of MTBU in leaching water was also investigated. The relative and cumulative breakthrough curves were obtained from disturbed soil columns. The presence and/or addition of organic matter drastically reduced the movement of the herbicide. On other hand, photocatalytic experiments showed that the addition of ZnO and TiO2 strongly enhances the degradation rate of this herbicide compared with the results of photolytic experiments under artificial light. ZnO appeared to be more effective in MTBU oxidation than TiO2. The results obtained point to the interest of using organic wastes and heterogeneous photocatalysis for reducing the pollution of groundwater by pesticide drainage.     

考虑群组行为的楼梯瓶颈处行人流模拟

为探究楼梯瓶颈处群组行为对行人流通行效率的影响,基于校园内的观测试验获取群组运动参数,采用Anylogic仿真平台建立考虑群组行为特征的楼梯瓶颈处人员运动模型,根据不同的群组运动参数、楼梯几何参数和障碍物布置方式对行人流通行时间与密度分布的影响开展数值模拟。结果表明:较大的群组比例和群组规模均会延长行人流通行时间,增加通行过程中的拥堵持续时间;在链状构型下,群组通行效率较高,而并排构型对人员通行造成的负面影响最大;在有群组和无群组情况下,楼梯位置变化会产生相反的通行效果;平行放置障碍物可以有效降低人群密度,提高群组行人流的通行效率。