A Practical Procedure for the Measurement of Fragmentation by Blasting by Image Analysis

Summary. The operation of a digital image analysis system in a limestone quarry is described. The calibration of the system, required in order to obtain moderately reliable fragmentation values, is done from muckpile sieving data by tuning the image analysis software settings so that the fragmentation curve obtained matches as close as possible the sieving. The sieving data have also been used to extend the fragment size distribution curves measured to sizes below the system’s optical resolution and to process the results in terms of fragmented rock, discounting the material coming from a loose overburden (natural fines) that is cast together with the fragmented rock. Automatic and manual operation modes of the image analysis are compared. The total fragmentation of a blast is obtained from the analysis of twenty photographs; a criterion for the elimination of outlier photographs has been adopted using a robust statistic. The limitations of the measurement system due to sampling, image processing and fines corrections are discussed and the errors estimated whenever possible. An analysis of consistency of the results based on the known amount of natural fines is made. Blasts with large differences in the amount of fines require a differentiated treatment, as the fine sizes tend to be the more underestimated in the image analysis as they become more abundant; this has been accomplished by means of a variable fines adjustment factor. Despite of the unavoidable errors and the large dispersion always associated with large-scale rock blasting data, the system is sensitive to relative changes in fragmentation.     

Spatial prediction of urban landslide susceptibility based on topographic factors using boosted trees

As global warming accelerates, abnormal weather events are occurring more frequently. In the twenty-first century in particular, hydrological disruption has increased as water flows have changed globally, causing the strength and frequency of hydrological disasters to increase. The damage caused by such disasters in urban areas can be extreme, and the creation of landslide susceptibility maps to predict and analyze the extent of future damage is an urgent necessity. Therefore, in this study, probabilistic and data mining approaches were utilized to identify landslide-susceptible areas using aerial photographs and geographic information systems. Areas where landslides have occurred were located through interpretation of aerial photographs and field survey data. In addition, topographic maps generated from aerial photographs were used to determine the values of topographic factors. A frequency ratio (FR) model was utilized to examine the influences of topographic, soil and vegetation factors on the occurrence of landslides. A total of 23 variables that affect landslide frequency were selected through FR analysis, and a spatial database was constructed. Finally, a boosted tree model was applied to determine the correlations between various factors and landslide occurrence. Correlations among related input variables were calculated as predictor importance values, and sensitivity analysis was performed to quantitatively analyze the impact of each variable. The boosted tree model showed validation accuracies of 77.68 and 78.70% for the classification and regression algorithms using receiver operating characteristic curve, respectively. Reliable accuracy can provide a scientific basis to urban municipalities for policy recommendations in the management of urban landslides.     

Concentrations of B,Sm, Gd and H in 24 Reference Materials*

Analysis of 24 reference materials for B, Sm, Gd, H, has been carried out over several years, using prompt gamma neutron activation analysis. The results are compared with values obtained by other workers, in order to better calibrate these standards. In most cases our results of repeated analysis of RMs show agreement with results from other laboratories, using various methods. A djustments to working values are proposed in some cases.     

Mineral and Physicochemical Systems of Evaporites: Geochemical and Thermodynamic Aspects

The distribution of mineral species by various systems in evaporites from Inder Lake (Kazakhstan) and Searles Lake (United States) is compared, and these localities are compared in terms of the distribution of species-defining elements. Ca, K, Na, Cl, B, and S are excess elements whose contents are high in both localities, whereas Si and Al are deficient. It is shown that comprehensive analysis of the evaporite mineralogy with selection of species-defining elements (mineral systems) can be used as an objective base for constructing quantitative physicochemical models on the formation of various types of evaporites. In addition, this approach allows a better understanding of the formation conditions of certain solid phases (including crystalline hydrates), which have been synthesized in aqueous–salt systems but have not yet been found in nature.     

Grinding of quartz in amine solutions

This study, initiated to investigate the effect of additions of surface active reagents on the wet-grinding of ores, has shown that improved grinding can be obtained at certain levels of amine concentration and pH. At some other levels, amine addition can also produce deleterious effects. The observed effects are discussed with the help of data obtained for flocculation and zeta potential of corresponding quartz/amine systems and those normally obtained for flotation. In addition, results of a photographic study of the milling process has been helpful in the study of the above effects. Most importantly, microscopic examination of the ground product (treated with dispersant and sieved) has clearly shown the possibilities for the existence of major experimental artifacts in the past works. Examination of the product under microscope is necessary to guarantee dispersion, especially if the system has been contacted with a surfactant or polymer.     

松花江哈尔滨段水系沉积物中无机元素环境标准样品的研制

介绍了松花江哈尔滨段水系沉积物环境标准样品的研制方法,对其中21个无机元素进行定值。采集的水系沉积物样品经自然阴干、研磨、筛分、混匀、装瓶和灭菌等加工处理后,分层随机抽取18瓶样品,在0.25 g样品取样量条件下,以铜、铅、锌、砷、汞、铁和铝为代表元素进行均匀性研究,结果表明样品均匀性良好。在室温避光保存条件下,以铜、铅、锌、砷和汞为代表元素,采用线性模型进行稳定性研究,在15个月研制期间样品未观察到不稳定性。由11家协作实验室对水系沉积物标准样品中的21个无机元素进行定值研究,经统计检验分析评定出20个元素的标准值和不确定度,1个元素给出参考值。研制成的标准样品已应用于土壤或水系沉积物样品中无机元素的监测。     

Particle size distribution analysis of sand-sized particles by laser diffraction: an experimental investigation of instrument sensitivity and the effects of particle shape

Laser diffraction is now widely used for particle size distribution analysis of sediments and soils. The technique can be very precise, and offers advantages of speed and cost over many other methods when used to analyse mixtures of sand, silt and clay. This study presents the results of an experimental investigation that examined the sensitivity of the Beckman-Coulter LS230 instrument to mixtures of different grain populations and differences in particle shape. The instrument was found to have high sensitivity to coarse particles in a finer matrix (detection threshold 1–2%), but much lower sensitivity to finer particles in a coarser mixture (detection threshold 12–17%). Experiments using near-spherical ballotini showed that laser analysis provides very similar values to dry sieving for the mean, median and mode, but for a range of natural sand samples values for the mean, median and mode were offset by 8–21%, with an average of ca 15%, compared with sieving. Analysis using a Beckman-Coulter RapidVUE instrument, which provides both size and shape information, provided support for the hypothesis that the differences between laser analysis and sieving are partly attributable to the effects of particle shape. However, an additional factor is the way in which the laser software interprets the optical diffraction data. The software predicts a high degree of log-normality in the size distribution, such that highly skewed, truncated or bimodal samples are poorly represented. Experiments using sieved fractions of ballotini indicated that, even with near-perfectly spherical particles, the particle size distribution predicted by the laser software includes a relatively large percentage of particles outside the sieve class limits.     

基于随机地震反应的桥墩-群桩-土相互作用研究

考虑地震动的随机性,利用复反应分析技术,采用随机地震反应计算方法对某一特大型桥梁群桩基础与土动力相互作用效应进行了数值试验研究。将土与群桩体系视为一个整体进行有限元离散,采用等效线性化方法考虑土体的动力非线性性能。将桥墩-群桩-土相互作用体系与自由场随机地震反应进行比较,结果表明：相互作用效应的影响与桩土模量差异以及土体与群桩基础距离有关;软土层剪应变水平及分布发生了显著变化,群桩基础两侧附近土域剪应变呈现明显的弧形分布;地表及浅层土体最大地震加速度反应有所减小,但覆盖层中下部土体加速度反应峰值明显增大,增幅达5 %～30 %左右;此外,地震地面运动的频谱成分存在显著差别。桥梁桩基础抗震设计中应充分考虑桥梁结构-群桩-土相互作用效应。     

氧化铁矿物催化分解苯酚的动力学速率及其产物特征

本文研究了针铁矿、纤铁矿、赤铁矿和磁铁矿在过氧化氢参与下催化分解苯酚的动力学速率与溶液pH值的关系,并用紫外吸收谱测定了反应产物的谱学特征。结果表明,纤铁矿反应体系催化分解苯酚的速率常数(k)最大,其余依次为磁铁矿、针铁矿和赤铁矿。在纤铁矿反应体系中又以pH=3.8时反应速率常数最大。除赤铁矿反应体系外,当溶液pH=3~4时苯酚被完全分解,并有50%~65%的有机碳(TOC)被矿化。在pH=3.25的赤铁矿反应体系中,苯酚大多仅被转化为多酚,小部分苯环被打开形成己烯酸。当溶液pH=4~5时,苯酚一般仅被转化为多酚类化合物,但TOC基本不变。当溶液pH>5时,苯酚没有发生明显的转化和矿化现象。     

The recharge of glacial meltwater and its influence on the geochemical evolution of groundwater in the Ordovician-Cambrian aquifer system,northern part of the Baltic Artesian Basin

The geochemical evolution of groundwater in the Ordovician-Cambrian aquifer system in the northern part of the Baltic Artesian Basin (BAB) illustrates how continental glaciations have influenced groundwater systems in proglacial areas. The aquifer system contains water that has originated from various end-members: recent meteoric water, glacial meltwater and relict Na-Cl brine. The saline formation water that occupied the aquifer system prior to the glacial meltwater intrusion has been diluted by meltwaters of advancing-retreating ice sheets. The diversity in the origin of groundwater in the aquifer system is illustrated by a wide variety in δ¹⁸O values that range from −11‰ to −22.5‰. These values are mostly depleted with respect to values found in modern precipitation in the area. The chemical and isotopic composition of groundwater has been influenced by mixing between waters originating from different end-members. In addition, the freshening of a previously saline water aquifer due to glacial meltwater intrusion has initiated various types of water-rock interaction (e.g. ion exchange, carbonate mineral dissolution).     

Comparison of metal homogeneity in grab,quartered, and crushed — sieved portions of stream sediments and metal content change resulting from crushing — sieving activity

Restricted grain size sediment samples were collected along two streams. Metal content in some samples may have been influenced by landfill emissions. Each sample was divided into a grab portion, a quartered portion, and a portion crushed and sieved to a smaller size and then quartered. A duplicate sample from each of these portions was extracted. The Cu, Pb, Zn, Co, Ba, Fe, Mn, and Ca quantities were determined for each duplicate sample. Relative standard deviation was used to reflect homogeneity of metal content. Metal occurrence represented speciated metals or major components of chemical phases. Results indicated that variation of metal content among portions was uniform and did not vary as a function of absolute metal quantity. Homogeneity was similar in the same size grab and quartered samples. A more homogeneous metal state was displayed by the crushed and sieved sediments. However, this activity enriched softer chemical phases and associated speciated metals. It was concluded that sediments need not be quartered to obtain a better homogeneity of metal distribution and that field samples should not be crushed and sieved prior to chemical analyses. Assessment of sediments affected by metal emission sources must include a knowledge of metal homogeneity in individual samples.     

Hypogeal geological survey in the “Grotta del Re Tiberio” natural cave (Apennines, Italy): a valid tool for reconstructing the structural setting

As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the ”Grotta del Re Tiberio” cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors’ surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area (e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures (e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping gypsum is more exposed to dissolution and recrystallization. The hypogeal geological survey, therefore, can be considered a powerful tool for integrating the surface and log data in order to enhance the reconstruction of the deformational history and to get a three-dimensional model of the bedrock in karst areas.     

Assessment of strut forces for braced excavation in clays from numerical analysis and field measurements

One important consideration in the design of a braced excavation system is to ensure that the structural bracing system is designed both safely and economically. The forces acting on the struts are often determined using empirical methods such as the Apparent Pressure Diagram (APD) method developed by Peck (1969). Most of these empirical methods that were developed from either numerical analysis or field studies have been for excavations with flexible wall types such as sheetpile walls. There have been only limited studies on the excavation performance for stiffer wall systems such as diaphragm walls and bored piles. In this paper, both 2D and 3D finite element analyses were carried out to study the forces acting on the struts for braced excavations in clays, with focus on the performance for the stiffer wall systems. Subsequently, based on this numerical study as well as field measurements from a number of reported case histories, empirical charts have been proposed for determining strut loads for excavations in stiff wall systems.     

Effects of hydrothermal alteration on Pb in the active PACMANUS hydrothermal field, ODP Leg 193, Manus Basin, Papua New Guinea: A LA-ICP-MS study

The conventional model of leaching volcanic rocks as a source of metals in a seafloor hydrothermal systems has been tested by examining the behavior of Pb and other trace elements during hydrothermal alteration. ODP Leg 193 drill sites 1188 (Snowcap) and 1189 (Roman Ruins) on Pual Ridge in the eastern Manus Basin offshore eastern Papua New Guinea provide a unique three-dimensional window into an active back-arc hydrothermal system. We investigate by means of a LA-ICP-MS microbeam technique the capacity of Pb to be leached from a host volcanic rock exposed to various types and intensities of alteration. Our results are in general agreement with previous studies that utilized bulk analytical techniques but provide a more detailed explanation of the processes.Fresh representative dacitic lavas from the Pual Ridge have an average whole rock Pb content of 5.2 ppm, an average interstitial glass Pb content of 5.6 ppm and an average plagioclase Pb content of 1.0 ppm. Altered matrix samples have highly variable Pb values ranging from 0 to 52.4 ppm. High Pb values in altered samples are associated with a low temperature chlorite and clay mineral assemblage, in some cases overprinted by a high temperature (up to 350 °C) silica-rich “bleaching” alteration. Only the most highly altered matrix samples have REE patterns that differ from the fresh Pual Ridge dacite. This may represent either different lava histories or alteration characteristics that have affected normally immobile REEs. Altered samples with the highest Pb values have similar REE patterns to those of the local unaltered lavas. They are compositionally similar to typical Pual Ridge dacites indicating a genetic relationship between the main regional volcanic suite and the subseafloor hydrothermally altered, Pb-enriched material.Relative loss/gain for Pb between the analyzed altered samples and a calculated precursor show a maximum relative gain of 901%. Samples with relative Pb gain from both drill sites are associated with lower temperature alteration mineral assemblages characterized by pervasive chloritization. The related lower temperature (220-250 °C) neutral to slightly acidic fluids have been ascribed by others to return circulation of hydrothermal fluids that did not interact with seawater. Because altered samples have a higher Pb content than the fresh precursor, leaching of fresh volcanic rocks cannot be the source of Pb in the hydrothermal systems.     

Test of a model for trace element partition during closed-system solidification of a silicate liquid

Distributions of trace elements during solidification of a basalt are adequately described by the model of Helmkeet al. (1972) for crystallization as a closed system. A hypidiomorphic granular basalt was coarsely crushed to particles < 2 mm in size, was sieved, and materials from nine size fractions were analyzed by neutron activation for REE, Co, Cr, Fe, Hf, Na, Sc, and Ta. Mineral separates from one of the size fractions were also analyzed.Trace-element concentrations of analyzed samples containing statistically significant numbers of mineral grains were matched very well by a mixing model whose end-member components were the analyzed major minerals and mesostasis. Highly accurate modal analyses of the analyzed materials were obtained from the mixing model. Differences in proportions of mesostasis (range 0.57–2%) were shown to be responsible for large differences in trace element concentrations among 0.25–1 g chips from a single hand-specimen of the basalt. Ilmenite in the basalt is badly contaminated with mesostasis.The closed-system model for crystallization yields values for temperature- and composition-averaged distribution coefficients for incompatible elements that are accurate to ? 15 to + 30%, and relative to each other are accurate to a few percent. The model demonstrates why some current practices for estimating values of distribution coefficients or of parent liquid compositions lead to errors of factors of several times.     

Modelling the Impact of Rockmass and Blast Design Variation on Blast Fragmentation

Most blast fragmentation models assume the rock mass properties. explosive properties and blast design variables to be constants and uniformly distributed within a blast. However, in reality all these input variables vary within a blast resulting in variation in the resulting fragmentation size distribution. A stochastic modelling approach is introduced in this paper to quantify this variation. This technique takes the input variables as statistical distributions rather than constants and through several thousand iterations, generates a statistical representation of the expected fragmentation resulting from a poduction blast. A case study of three production blasts from a large open pit mine are presented and the modelled fragmentation 'envelope' shows good agreement with the fragmentation 'envelope' estimated from Split image analysis. The various blast-related parameters influence different parts of the fragmentation distribution, e.g., rock strength and explosive velocity of detonation have most impact on the fines. The technique is used to identify the parameters that have the greatest influence on various size fractions. Such an analysis will be useful to direct resources to efficiently minimise the variation.     

Dissipative Structures of Rock—and Ore—forming Systems in Faults

The dissipative structure is an ordered structure.When a ssyterm is far from reaching equilibrium in the condition of non-equilibrium and exchanges some energy and material with the surroundings,this structure will be formed and preserved.Starting with the analysis of practical data,we attempt to use this theory to discuss the tectono-geochemical problems of some rock and ore-forming systems in faults.1.Ordered structure:Under the geological condition,due to the opening of a system in which energy and material are involved in geochemical action,the entropy tends to reduce gradually and substances evolve from non-ordered to ordered in structure.In the processes of formation of rocks and ores in faults,various layer-bands will be formed in rocks.2.Functional action:The physico-chemical activities which include pressure-creeping and thermal-diffusion as well as liquid diffusion have been shown.3.Fluctuating cycle:In the process of metamorphism,various changes in pressure,temperature and liquid are of fluctuation and periodicity.These may play an important role in the formation of rocks and minerals and the occurrence of ordered structures in fault zones.A few examples of mineral deposits in the middle and lower Yangtze River Valley are presented here,and the dissipative activities of rock-forming minerals and mineral-forming elements have been preliminarily established.     

Comprehensive study on automation of toxic gas measurement

The condition of the ambient air must be continuously checked to detect hazardous gas leakage and ensure the safety of employees in hazardous gas production and storage areas. Detection and elimination of hazardous gas leaks can be done with various complex measurement, safety, and disposal systems. These measurement systems consist of different types of sensor and require control and monitoring system. This leads to high investment and operating costs. In this study, semi-continuous measurement system automation with a single set of sensors working by taking air samples from different points over specific periods has been designed to reduce investment, operation, and maintenance repair costs. In the design, the measurement points are divided into zones and codes in the automation system. Thus, it is aimed to keep a constant record of what the air sample is coming from and what its content is. As a result, it has been determined that it is possible to establish a measurement and automation system similar to existing hazardous gas measurement systems with less investment and operating costs. The proposed automation system has been applied in the industrial storage area. In addition, a cost analysis has been performed and compared with conventional systems.     

Shallow landslides triggered by rainfalls: modeling of some case histories in the Reggiano Apennine (Emilia Romagna Region, Northern Italy)

On April 10–11, 2005, the Emilia Romagna Apennine was affected by an intense rainfall event that triggered dozens of soil slips in the Province of Reggio Emilia. These shallow landslides occurred mainly on slopes of cultivated lands, often blocking roads, causing damages to crops and economic loss. Based on the analysis of an inventory of aerial photographs, it was possible to locate 45 sites where soil slips have occurred. In this paper, the area of study is described from a geological and climatic point of view. The authors analyze both the predisposing factors, related to the morphology of the territory, and the phenomena triggering factors, related to the rain trend. Once the geometrical features and characteristics of the soil slopes were available, a physically based triggering model, recently developed by the authors, was locally applied at each site. The model, which is based on the limit equilibrium method and on the hypothesis of infinite slope, is briefly described. It assumes a partial saturation condition of the soil and provides the safety factor of each slope as a function of time-variable rainfall intensity. The choice of the input parameters of the model is explained in detail. It is underlined, in particular, how the only parameter that has been determined through a procedure of back analysis, i.e., the discharge capability, is comparable to the typical permeability values obtained through field measurements by other authors, for similar kinds of soils and conditions. In this article, the results of the application of our model to the study areas, within a three-year time frame, are presented. Furthermore, on the basis of the analysis carried out, some observations on the operating mode of the model are carried out and its ability to predict a phenomenon triggering is evaluated.     

The effects of magma replenishment processes on 238U-230Th disequilibrium

Short lived isotope data are increasingly used to investigate magma chamber residence times. Arc lavas have excellent potential as tracers of magma evolution because their magmas are often out of U-series isotope equilibrium, and some arc magmas have yielded surprisingly old pre-eruption U-series ages from mineral separates. A model is presented to examine the behaviour of U-Th isotopes for a range of conditions between closed system and steady-state magmatic systems. Magmas can be maintained out of secular equilibrium for long periods of time by periodic mixing events with new magma batches. The latter results in oscillations in (²³⁰Th/²³²Th) consistent with the relatively constant values observed in lavas of different ages from some centres. The effects of periodic reinjection of magma and mixing of old and young crystals on U-series mineral isochrons are also considered. Mixtures of crystals produced by either replenished or closed system processes can readily result in linear arrays. In many cases it may be valid to interpret these as minimum average residence times for the crystals, whereas the liquid residence times calculated from U-series data for periodically replenished systems are maximum values.