沟谷泥石流运动过程模型试验

泥石流运动过程是泥石流运动力学核心内容之一.以新疆天山公路K630泥石流为原型,选取几何相似比1:650,推导了泥石流质量、固液两相流速和泥石流冲击力相似比,以流通区为核心,建造了沟谷泥石流试验模型.试验结果表明,泥石流运动具有显著的阵流特性,阵流间隔时间为10s左右,其间嵌套2~3次弱阵现象;阵流期间,泥石流流速和冲击力均较大;从流通区的源头至沟口,流速呈现非线性增大趋势,且泥石流体中固液两相流速变化趋势相似,弯道处泥石流超高现象显著;泥石流运动初期由于泥石流体中固相和液相混和搅拌不均匀而呈现稀性泥石流特征,随后粘性特性增强.这些现象与现场观测结果基本一致.     

Processes affecting the movement of organochlorine pesticides (OCPs) between soil and air in an industrial site in Turkey

Soil and atmospheric concentrations, dry deposition and soil-air gas exchange of organochlorine pesticides (OCPs) were investigated at an industrial site in Aliaga, Izmir, Turkey. Current-use pesticides, endosulfan and chlorpyrifos, had the highest atmospheric levels in summer and winter. Summertime total (gas + particle) OCP concentrations in air were higher, probably due to increased volatilization at higher temperatures and seasonal local/regional applications of current-use pesticides. Particle deposition fluxes were generally higher in summer than in winter. Overall average dry particle deposition velocity for all the OCPs was 4.9 ± 4.1 cm s⁻¹ (average ± SD). ΣDDXs (sum of p,p′-DDT, p,p′-DDD, and p,p′-DDE) were the most abundant OCPs in Aliaga soils (n = 48), probably due to their heavy historical use and persistence. Calculated fugacity ratios and average net gas fluxes across the soil-air interface indicated volatilization for α-CHL, γ-CHL, heptachlorepoxide, cis-nonachlor, trans-nonachlor, and p,p′-DDT in summer, and for α-CHL, γ-CHL, trans-nonachlor, endosulfan sulfate, and p,p′-DDT in winter. For the remaining OCPs, soil acted as a sink during both seasons. Comparison of the determined fluxes showed that dry particle, gas-phase, and wet deposition are significant OCP input mechanisms to the soil in the study area.     

高气速间歇式生物过滤去除高负荷H2S

采用生物过滤法,以鸡粪堆肥和PE混合物为填料,在高气速条件下间歇式处理高负荷H2S废气。空床停留时间为20、15、10、6.7和5 s时,入口浓度3 000 mg/m3下的平均去除率分别为100%、100%、96.5%、89.2%和90.5%。高气速EBRT为5 s时,高入口负荷2 147 g/(m3.h)时的去除负荷为2 023 g/(m3.h),去除率达94%。采用Michaelis-Ment-en模型进行生物降解宏观动力学研究,其中Ks为550 mg/m3,Vm为6.8×104g/(m3.d)。结果表明,在实验温度17～24℃,湿度30%～50%下,生物过滤法间歇式处理高气速高负荷H2S的去除性能好。     

钻孔灌注桩的超声波透射法检测

大直径超长桩的桩身混凝土质量检测一直是困扰工程界的一个难题。本文提出和探讨了大直径超长桩桩身混凝土质量的超声波透射检测方法、技术及可靠程度。工程实践证明采用超声波透射法对大直径超长桩检测 ,其检测精度高 ,结果直观可靠 ,可以较详细查明桩身内部缺陷的性质、深度位置、范围大小及严重程度 ,为控制大直径超长桩桩身混凝土质量提供了一种有效的检测方法。     

排放源烟道气二噁英空间分布对监测结果的影响

针对生活垃圾焚烧企业烟气排放烟囱6个断面单点采样的试验结果,分析按照《固定污染源排气中颗粒物测定与气态污染物采样方法》(GB/T 16157—1996)多断面点采样与单一固定断面点采样对监测结果的影响。试验表明,烟道气在不同断面点质量浓度分布差异较大,相对于样品实际监测值,各断面点二噁英毒性当量浓度最大正偏差达到+306%,最大负偏差达到-96%,测定的18个断面点样品,只有2个样品与实际样品监测值相近。     

ANALYSIS OF WIND- AND SHIP-INDUCED SEDIMENT RESUSPENSION IN DULUTH-SUPERIOR HARBOR1

ABSTRACT: Suspended solids and ammonium concentration profiles measured at five locations in Duluth-Superior Harbor during July-October 1985 were analyzed to quantify wind and ship effects on sediment resuspension and resulting harbor water quality. Wind components from the SE quadrant correlated strongly with depth-averaged suspended solids concentrations that were unaffected by ship passage or thermal stratification. Winds from that quadrant have the largest fetch in the harbor. The highest correlation (r²= 0.93) was with the 6-hour average of the ESE wind velocity component. Multiple linear regression analysis of data from post-ship passage concentration profiles yielded numerical estimates of settling velocities of 0.08 to 0.25 cm s^?1, typical of ship-resuspended sediments, and vertical eddy diffusivities of 4 to 13 cm² s¹. The results suggest that ambient vertical eddy diffusivities in the harbor are less than 4 cm² s^?1 in the absence of ship passages and with winds less than 5 m s^?1 (10 knots).     

DOWNSTREAM CHANNEL GEOMETRY FOR USE IN PLANNING-LEVEL MODELS1

ABSTRACT: There is considerable potential for use of channel dimension data in planning-level models for resource and impact assessment. The channel dimension data is used to route flows and sediment through the basin. The cost of obtaining actual surveyed data for large watersheds is typically prohibitive. Predictive equations have been developed based on 674 stations from watersheds across the United States which encompass a wide variety of channel types and sizes. These equations were tested against an independent data set and found to be adequate for use in planning-level models. Future research is advocated which would include data from regions and stream types not included in this study.     

MEASURED AND PREDICTED VELOCITY AND LONGITUDINAL DISPERSION AT STEAI)Y AND UNSTEADY FLOW,COLORADO RIVER,GLEN CANYON DAM TO LAKE MEAD1

ABSTRACT: The effect of unsteadiness of dam releases on velocity and longitudinal dispersion of flow was evaluated by injecting a fluorescent dye into the Colorado River below Glen Canyon Dam and sampling for dye concentration at selected sites downstream. Measurements of a 26-kilometer reach of Glen Canyon, just below Glen Canyon Dam, were made at nearly steady dam releases of 139, 425, and 651 cubic meters per second. Measurements of a 380-kilometer reach of Grand Canyon were made at steady releases of 425 cubic meters per second and at unsteady releases with a daily mean of about 425 cubic meters per second. In Glen Canyon, average flow velocity through the study reach increased directly with discharge, but dispersion was greatest at the lowest of the three flows measured. In Grand Canyon, average flow velocity varied slightly from subreach to subreach at both steady and unsteady flow but was not significantly different at steady and unsteady flow over the entire study reach. Also, longitudinal dispersion was not significantly different during steady and unsteady flow. Long tails on the time-concentration curves at a site, characteristic of most rivers but not predicted by the one-dimensional theory, were not found in this study. Absence of tails on the curves shows that, at the measured flows, the eddies that are characteristic of the Grand Canyon reach do not trap water for a significant length of time. Data from the measurements were used to calibrate a one-dimensional flow model and a solute-transport model. The combined set of calibrated flow and solute-transport models was then used to predict velocity and dispersion at potential dam-release patterns.     

THE EFFECTS OF A MOVING RAINSTORM ON DIRECT RUNOFF PROPERTIES1

ABSTRACT: The effects of a moving rainstorm on flood runoff characteristics were investigated. A flood hydrograph simulation model called “FH-Model” and a natural watershed were used. A hypothetical rainstorm of 50 years recurrence interval, 75 mm depth, and 4 hours duration was used to show the effects of velocity and direction of the moving rainstorm on the runoff characteristics. Compared with an equivalent stationary rainstorm (ESRS), the peak flow caused by a rainstorm moving in a downstream direction with a speed equal to channel velocity, V, was 27.5 percent higher and the peak flow caused by the same rainstorm moving in an upstream direction was 21.7 percent smaller. These percentages reduced to 10.5 percent and 8.6 percent for storms moving downstream and upstream, respectively, at three times the channel velocity, 3V. There were negligible differences in the time of peak, T_p between runoff caused by storms moving downstream and runoff produced by ESRS. However, T_p for a storm moving upstream at V velocity was 82 percent higher than that produced by ESRS, but was reduced to 27 percent higher when the storm velocity was 3V.     

VELOCITY EQUATION FOR WATER QUALITY MODELING IN GEORGIA1

ABSTRACT: Tabletop water quality modeling still plays an important role in the water pollution control activities of the Georgia Environmental Protection Division. Tabletop models are those developed with out the aid of extensive field data. One important component of GEORGIA DOSAG, our basic water quality model, is the equation used to predict flow through velocity. However, Georgia is characterized by wide physiographic diversity which reduces the effectiveness of uncalibrated velocity equations. Using 15 years of accumulated time-of-travel studies, a series of empirical velocity equations were developed and calibrated to various physiographic conditions in Georgia. Equations are available for each major soil province and for three stream flow ranges within each province - Q<100 cfs, 100<Q<1000 cfs, and Q>1000 cfs. Now, in the absence of extensive field data, we have data based velocity equations which can be tailored to each site under study.