汝箕沟煤矿煤灰熔点的逐步回归分析     

马振海  赵志根  黄文辉 《中国煤炭地质》2010,(11):7-9

煤灰熔点是评价煤工业用途的一项重要指标,针对矿区煤质灰熔点建立适宜的数学模型是一个值得重视的问题。根据逐步回归分析的基本原理,利用在汝箕沟煤矿收集的43组灰分产率、灰成分与灰熔点数据,建立了该矿煤的灰熔点与显著变量之间关系的回归方程。通过F-检验和相关系数检验,表明回归方程有一定的置信度,误差分析显示回归分析效果较好。  相似文献   

A field,laboratory, and literature review evaluation of the water retention curve of volcanic ash soils: How well do standard laboratory methods reflect field conditions?     

Giovanny M. Mosquera  Marín Franklin  Feyen Jan  Célleri Rolando  Breuer Lutz  Windhorst David  Crespo Patricio 《水文研究》2021,35(1):e14011

Accurate determination of the water retention curve (WRC) of a soil is essential for the understanding and modelling of the subsurface hydrological, ecological, and biogeochemical processes. Volcanic ash soils with andic properties (Andosols) are recognized as important providers of ecological and hydrological services in mountainous regions worldwide due to their large fraction of small size particles (clay, silt, and organic matter) that gives them an outstanding water holding capacity. Previous comparative analyses of in situ (field) and standard laboratory methods for the determination of the WRC of Andosols showed contrasting results. Based on an extensive analysis of laboratory, experimental, and field measured WRCs of Andosols in combination with data extracted from the published literature we show that standard laboratory methods using small soil sample volumes (≤300 cm³) mimic the WRC of these soils only partially. The results obtained by the latter resemble only a small portion of the wet range of the Andosols' WRC (from saturation up to −5 kPa, or pF 1.7), but overestimate substantially their water content for higher matric potentials. This discrepancy occurs irrespective of site-specific land use and cover, soil properties, and applied method. The disagreement limits our capacity to infer correctly subsurface hydrological behaviour, as illustrated through the analysis of long-term soil moisture and matric potential data from an experimental site in the tropical Andes. These findings imply that results reported in past research should be used with caution and that future research should focus on determining laboratory methods that allow obtaining a correct characterization of the WRC of Andosols. For the latter, a set of recommendations and future directions to solve the identified methodological issues is proposed.  相似文献   

Late Holocene diatoms in Lake Poukawa: Effects of airfall tephra and changes in depth     

M. A. Harper  R. Howorth  M. Mcleod 《新西兰海洋与淡水研究杂志》2013,47(1):107-118

Lake Poukawa, a shallow hardwater lake, is situated on calcareous lake silt overlying peat and alluvium. Two tephra layers, Taupo Pumice and Waimihia Lapilli, aged c. 2000 and 3500 calendar years respectively, were present in four cores (c. 6 m long) of the lake sediment. The diatom flora of the cores was studied to find any indication of changes in the lake morphology and to assess the effects of tephra deposition. Increased abundance of small Fragilaria spp. appears to indicate periods when the lake was less extensive, c. 3700–3500 y ago, and c. 2800–3000 y ago. In the recent past, increased abundance of Fragilaria spp. in lake sediment near the present southern margin almost certainly coincides with artificial draining since A.D. 1931. The occurrence of marine sponge spicules in the cores probably indicates that rates of erosion in the catchment were low before 2500 y ago and high 100–0 y ago. Diatom samples taken at close intervals adjacent to the Taupo and Waimihia tephras indicate that above the ash estimated numbers of diatoms per unit dry weight increase, but the proportion of epiphytic species decreases. Some of the possible causes of this increase are discussed. The tephra layers possibly preserved more diatom frustules, or increased diatom growth by supplying silica, phosphorus, and sulphur nutrients directly, or organic matter from vegetation damage in the surrounding catchment. Alternatively, in shallow hardwater lakes, if acids are deposited with the tephra and its fine particles form an impermeable layer on the calcite sediments the lake will become less alkaline and nutrient depleted.  相似文献   

粉煤灰处理软土地基的试验研究   总被引：4，自引：1，他引：4  

徐红  罗国煜 《工程地质学报》2001,9(3):286-290

利用淤泥质粘土掺入不同比例的粉煤灰, 分别进行了渗透、固结、直接剪切及三轴剪切试验, 详细研究了粘土掺入粉煤灰后其工程力学性能变化的特征以及粉煤灰加固软土的机理。试验结果证实, 利用粉煤灰处理软土地基是-种所需投资较少且有明显效果的方法, 并可带来良好的环境效益和社会效益。  相似文献   

富拉尔基热电总厂粉煤灰敏感性指标的试验研究   总被引：1，自引：1，他引：1  

赵红威  薛远峰  许晖  张喜发 《水文地质工程地质》2001,28(1):49-51,62

以富拉尔基热电总厂粉煤灰为研究对象，对其与水和温度有关的各项敏感性指标－渗透稳定性、软化特性、冻融强度损失和冻胀性进行了试验研究。  相似文献   

Properties and performance of a high volume fly ash grout     

Ayşe Pekrioglu Balkis 《Marine Georesources & Geotechnology》2020,38(1):73-82

Abstract

This study investigated the penetrability of high volume fly ash cement suspensions prepared with and without superplasticizer into sandy soil having different relative densities with 30%, 60%, 73%, and 83% through permeation grouting. Class C fly ash was used due to its pozzolanic activity and fineness. Due to engineering characteristics and cost, cementitious grouts are the most commonly used grout in both waterproofing and ground strengthening. Fly ash-cement grouts have relatively constant and low viscosity values for a reasonable period after preparation, exhibit limited or negligible bleed capacity and set and develop satisfactory strength within a relatively short period. Modeling of grouting of soil was done in laboratory and improvements in physical and mechanical properties of grouted soil were analyzed. Unconfined compressive strength, shear strength and permeability characteristics of grouted soil were studied as a result. Unconfined compressive strength values of grouted sand with high volume fly ash ranged between 410 and 1107?kPa. Morover, cohesion values were comparable to microfine cement grouting ranging from 373 to 511?kPa. Furthermore, permeability values were also approximately equal to the permeability of impervious liners, which is around 1?×?10^?7?cm/s. The findings support the applicability of grouting in different applications.  相似文献   

深圳福田红树林区7种红树植物叶热值的季节变化   总被引：16，自引：0，他引：16  

林益明  柯莉娜  王湛昌  林鹏 《海洋学报》2002,24(3):112-118

对广东深圳福田红树林自然保护区的7种红树植物叶热值和灰分含量的季节变化进行了研究.结果表明:(1)7种红树植物叶的灰分含量存在差异,且具有一定的季节变化;(2)7种红树植物叶中,大戟科的海漆、梧桐科的银叶树这两种红树植物叶的干重热值与灰分含量具有极显著的线性相关,其余5种红树植物叶的干重热值与灰分含量相关性不显著;(3)从干重热值的季节变化来看,2001年1月(冬季)、2001年4月(春季)7种红树植物叶的干重热值与灰分含量有极显著的线性相关,2000年7月(夏季)7种红树植物叶的干重热值与灰分含量有显著的线性相关,2000年10月(秋季)7种红树植物叶的干重热值与灰分含量相关性不显著;(4)7种红树植物叶的去灰分热值与干重热值存在不同的季节变化趋势,但7种红树植物叶的去灰分热值均是秋季最高.  相似文献   

Settlement of compacted ash fills   总被引：1，自引：0，他引：1  

Ashutosh Trivedi  Vijay K. Sud 《Geotechnical and Geological Engineering》2007,25(2):163-176

The coal ash is a by-product of coal-fired thermal power station. It is extensively used as a geo-material for landfill. The compacted ash is used as a structural fill if it is properly characterized for load-bearing capacity and settlement. The main objective of the present work is to characterize ash material and to evaluate its settlement characteristics. The ash is normally compacted by vibration at or near optimum moisture for its performance as structural fill. The overt characteristics of ashes are viewed similar to cohesionless soils. However, the mass behavior may have differences due to the subtle influence of chemical and physical processes involved in its formation. The empirical and analytical methods predicting settlement of footing under static loading require direct or indirect measurement of density and stress state in the deposit. In the present work, experimental investigations for settlement prediction were carried out on compacted coal ash produced at Ropar thermal power station in India, which was conveniently classified as ASTM class F ash. The settlement was experimentally obtained for the rigid plates having least dimension more than 0.3 m on ashes compacted at varying degree of compaction. The predicted settlement based on the observed data of coal ash using conventional techniques for soils was found to be conservative. A relationship between settlement and foundation size is proposed at varying compaction to obtain the settlement of compacted ash. At a higher degree of compaction, the settlement of a foundation may not exceed the allowable settlements in the working stress range.  相似文献   

Volcanic particle aggregation in explosive eruption columns. Part I: Parameterization of the microphysics of hydrometeors and ash   总被引：1，自引：3，他引：1  

C. Textor  H.F. Graf  M. Herzog  J.M. Oberhuber  William I. Rose  G.G.J. Ernst   《Journal of Volcanology and Geothermal Research》2006,150(4):359-377

  相似文献   

Simulation of syn-eruptive floods in the circumvesuvian plain (southern Italy)     

M. Favalli  M. T. Pareschi  G. Zanchetta 《Bulletin of Volcanology》2006,68(4):349-362

During explosive eruptions the deposition of fine-grained volcanic ash fallout reduces soil permeability, favouring runoff of meteoric water and thus increasing the occurrence of catastrophic floods. A fully dynamic, two-dimensional model was used to simulate flooding scenarios in the Vesuvian area following an explosive volcanic eruption. The highest risk occurs in the catchment area of the Acerra-Nola Plain N and NE of Vesuvius. This plain has a population of 70,000 living in low-lying areas. This catchment area is vulnerable to ash fall because it lies downwind of the dominant synoptic circulation and it lacks a natural outflow toward the sea. Our numerical simulations predict dangerous scenarios, even in quiescent periods, during extreme rain events (return periods of 200 years have been considered), and a significant increase in the extent of the flooded areas due to renewed volcanic activity. Based on these simulations a hazard zonation has been proposed. Editorial responsibility: A Woods  相似文献