Sourcing fire ash on archaeological sites in the Western and Northern Isles of Scotland,using mineral magnetism

The application of a new technique developed to identify different fuel sources from ash on nine archaeological sites in the Western and Northern Isles of Scotland is presented. The technique is based on variations observed in the mineral magnetic signatures that derive from the experimental burning of different fuels. The application of the technique is successful, demonstrating both uniformity and diversity in fuel use. A marked continuity of practice in fuel procurement is apparent over thousands of years from seven sites in Lewis, with well‐humified peat the dominant fuel source. This implies a long‐term stability in the division and tenure of the peatlands. Greater magnetic variation is displayed by the samples from Cladh Hallan, South Uist, and Scatness, Shetland, suggesting more diverse fuel procurement strategies were in operation at these sites. The uniformity and diversity in fuel types also has implications in terms of the residuality of plant remains from the fuel source within archaeobotanical assemblages recovered from the sites. © 2007 Wiley Periodicals, Inc.     

Solving 3D boundary element problems using constrained iterative approach

Some major challenges for geophysicists and structural geologists using three-dimensional boundary element method codes (3D-BEM) are: (1) reducing the amount of memory required to solve large and dense systems and (2) incorporation of inequality constraints such as traction inequality constraints (TIC) and displacement inequality constraints (DIC). The latter serves two purposes. First, for example, inequality constraints can be used to simulate frictional slip (using TIC). Second, these constraints can prevent element interpenetration while allowing opening mode (using DIC). We have developed a method that simultaneously incorporates both types of functionality of the inequality constraints. We show that the use of an appropriate iterative solver not only avoids the allocation of significant memory for solving the system (allowing very large model computation and simplifying parallelization on multi-core processors), but also admits interesting features such as natural incorporation of TICs and DICs. Compared to other techniques of contact management (e.g., Lagrange multipliers, penalty method, or complementarity problem), this new simple methodology, which does not use any incremental trial-and-error procedures, brings more flexibility, while making the system more stable and less subject to round-off errors without any computational overhead. We provide validations and comparisons of the inequality constraints implementation using 2D analytical and numerical solutions.     

Investigating the potential of using environmental magnetism techniques as pollution proxy in urban road deposited sediment

The use of mineral magnetic techniques as pollution proxy for road deposited sediment was explored using various statistical approaches. Standard techniques were adopted for measurement of mineral magnetic and geochemical parameters. The analyses of magnetic parameters revealed that the samples were dominated by ferrimagnetic minerals and multidomain grains. This implied that the magnetic fractions in the samples might be of anthropogenic origin. Results also indicate that the samples were dominated by low coercive, magnetically soft minerals. Thermomagnetic curves confirmed magnetite as the remanence bearing magnetic mineral having a Curie point temperature of ~580 °C. The strong association observed between magnetic susceptibility, susceptibility of anhysteric remanent magnetization and saturation isothermal remanent magnetization and aluminum, titanium, manganese, iron, chromium and lead demonstrated that these metals occurred as ferrimagnetic particles of technogenic origin resulting from vehicular sources. Assessment of pollution status of the road deposited sediment identified silicon and lead as the priority pollutants of concern. Generally, pollution load index was <1 (mean, 0.66 ± 0.14), indicating that the samples were not polluted in the overall, but the metals were in the buildup stage requiring constant monitoring. The sources of pollutants from principal component and cluster analyses identified the sources of pollution to be mainly from vehicular emissions such as brake linings, exhaust materials, tire wear, corroded metal parts, abrasion of lubricating oil and road construction materials. This study found that mineral magnetic techniques offer great potential as pollution proxy for soil pollution studies.     

Prediction of swelling pressure of soil using artificial intelligence techniques

The swelling pressure of soil depends upon various soil parameters such as mineralogy, clay content, Atterberg’s limits, dry density, moisture content, initial degree of saturation, etc. along with structural and environmental factors. It is very difficult to model and analyze swelling pressure effectively taking all the above aspects into consideration. Various statistical/empirical methods have been attempted to predict the swelling pressure based on index properties of soil. In this paper, the computational intelligence techniques artificial neural network and support vector machine have been used to develop models based on the set of available experimental results to predict swelling pressure from the inputs; natural moisture content, dry density, liquid limit, plasticity index, and clay fraction. The generalization of the model to new set of data other than the training set of data is discussed which is required for successful application of a model. A detailed study of the relative performance of the computational intelligence techniques has been carried out based on different statistical performance criteria.     

Sourcing sedimentary cherts with archaeological use through the combination of chromatographic and spectroscopic techniques

The nature and distribution of organic matter in geological cherts of archaeological use can serve to estimate the sources and origins of some remains of lithic industry. For example, organic and biomarker analysis can provide information to allow a deeper insight into source catchment areas, artefact displacement or the way in which the artefacts were employed. In this work, soluble (bitumen) and insoluble (kerogen) organic matter were isolated from several chert samples with different depositional history and analysed by means of gas chromatography–mass spectrometry (GC–MS) and spectroscopic techniques such as infrared and Raman spectroscopy. Chemometric treatment of the results allowed observation of differences between organic matter content on the basis of the depositional setting of the cherts. Samples with a continental deposition seemed to preserve more organic matter with little alteration. The hydrocarbon profiles of these samples were dominated by high molecular weight n-alkanes, alkylcyclohexanes and isoprenoid groups which allowed distinguishing them from the rest of the analysed samples.     

Mapping the archaeological soil archive of sand and gravel mineral reserves in Britain

Primary sand and gravel deposits in Britain play an important role in preserving our cultural heritage and are also a valuable aggregate resource. While an understanding of the extrinsic properties of the soil archive (such as pH, redox, groundwater) can provide a firstorder assessment of the potential risk to any archaeologically sensitive deposits, we have very poor definition of spatial variations in the extrinsic properties of soil that influence archaeological preservation at a regional and national scale. Developments in digital geological mapping, remote sensing, and geochemical survey data undertaken by the British Geological Survey (BGS) have, however, significantly extended capabilities in this respect and can potentially be used to provide a primary assessment of the sensitivity of the present soil archive and the potential risk from changes to the soil process on cultural material in areas earmarked for aggregate extraction. Two of the major factors affecting archaeological preservation—soil acidification and groundwater—can be mapped or predicted at scales of better than 1:50,000 across increasingly large parts of the country using a combination of regional hydrogeological, geophysical, and geochemical data. Additional data from site investigations may further refine preservation potential as a function of changes in redox potential and acidity. These data, maps and models can be used to (1) better establish a baseline for archaeological preservation at a regional and national scale and (2) improve our understanding of how the physical and chemical properties of the near surface environment can be managed to sustainably preserve archaeological materials in areas impacted by sand and gravel extraction. © 2009 Wiley Periodicals, Inc.     

土壤磁性测量在寻找可地浸砂岩型铀矿床中的应用

本文探讨了应用土壤磁性测量寻找可地浸砂岩型铀矿床的可行性 ,并通过在内蒙古东胜地区的应用研究总结了可地浸砂岩型铀矿床上土壤磁性参数异常的特征     

土质滑坡地表倾斜变形特征与基于MEMS的倾斜变形监测技术初探

随着现代信息技术快速发展,人们获取滑坡现场各类监测信息的能力越来越强,积累的现场监测数据也愈来愈多,如何充分、精细化地利用监测数据已成为滑坡监测预警工作中重点关注的问题。为此,本文以土质滑坡为研究对象,采用强度折减有限元方法开展地表倾斜变形时空演化特征理论研究,发现地表倾斜变形在滑动面扩展至贯通期间出现"速率排序跃迁"现象,在滑动面贯通后出现"速率突变"现象。采用地表倾斜变形与内部滑动面之间的这种定量化关联特性,可以为土质滑坡中短期预测预报方法研究提供新的视角和方向。利用理论研究成果,本文进一步开展地表倾斜变形监测关键技术研究,讨论基于MEMS加速度计的倾角传感器的测量原理与测量精度,分析环境温差波动对倾角测量误差的影响,最后介绍基于竖直倾角测量方式研制的普适型滑坡地表倾斜变形监测设备——坡体浅层倾斜变形测量仪。     

SH材料加固夯筑遗址土耐久性试验及机理研究

以添加SH材料加固的明长城古浪段夯筑遗址土为研究对象,对其重塑样进行紫外老化试验、冻融循环试验及耐盐、耐碱试验,研究其力学强度特征及耐久性能,并采用扫描电镜（SEM）、EDS能谱分析以及粒度分析研究SH材料加固夯筑遗址土的机理。试验结果表明,经紫外老化的SH固化后试样的无侧限抗压强度随老化时间增长呈先增后降,SH含量高的试样强度呈一直增长的趋势;随着冻融循环次数的增加,试样的无侧限抗压强度逐渐降低,质量损失率逐渐增加,其中SH固含量为0.8%的试样表现出极好的耐冻性能;相比素土,加固后的试样耐盐、耐碱性能明显有所提高。由机理分析得出,SH材料主要通过团聚、氢键、架桥和包裹等作用使土颗粒排列紧密、增强连接性,提高了遗址土的各种性能;SH材料加固夯筑遗址土具有良好的耐久性能。     

Source and distribution of metals in urban soil of Bombay,India, using multivariate statistical techniques

Simplification of a complex system of geochemical variables obtained from the soils of an industrialized area of Bombay is attempted by means of R-mode factor analysis. Prior to factor analysis, discriminant analysis was carried out taking rock and soil chemical data to establish the anthropogenic contribution of metals in soil. Trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are expressed in terms of three rotated factors. The factors mostly indicate anthropogenic sources of metals such as atmospheric fallout, emission from different industrial chimneys, crushing operations in quarries, and sewage sludges. Major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, and Fe) are also expressed in terms of three rotated factors indicating natural processes such as chemical weathering, presence of clay minerals, and contribution from sewage sludges and municipal refuse. Summary statistics (mean, standard deviation, skewness, and kurtosis) for the particle size distribution were interpreted as moderate dominance of fine particles. Mineralogical studies revealed the presence of montmorillonite, kaolinite, and illite types of clay minerals. Thus the present study provides information about the metal content entering into the soil and their level, sources, and distribution in the area.     

Macro- and micro-ecological reconstruction using plant opal phytolith data from archaeological sediments

Phytolith analysis is rapidly maturing into a robust and powerful paleobotanical data system. Many plant groups can be identified to family or subfamily, and even species identification has been suggested. Distinctive phytoliths occur abundantly in members of the grass family and are also found in several other groups including rushes, sedges, palms, conifers, deciduous trees, and other dicotyledonous plant taxa. Soil phytolith assemblages have provided paleobotanical data on the order of thousands to millions of years ago. Moreover, as test cases for analysis in soil have increased, an emerging pattern indicates that phytolith populations are stable decay-in-place residues following deposition in sediments. Phytolith studies reflect both macroecological as well as subtle microecological, ecotonal differences, and/or very specific ethnobotanical and cultural activities. Phytolith analysis is a superlative source of botanical information in narrowly defined contexts of archaeological sediments.     

Geochemical and mineralogical investigation of domestic archaeological soil features at the Tiel-Passewaaij site,The Netherlands

Archaeological soil features can be defined as areas of staining in ancient cultural soil horizons and are frequently used in surveys to locate sites and activity areas. Visual observation of these features, however, provides only limited information on their origin and the processes leading to their formation and this limits site interpretation. This paper presents the results of geochemical and mineralogical analyses of domestic archaeological soil features in order to assess their composition, formation pathway and origin. The greenish soil features studied here belong to a house plan from a Roman farmhouse located at the Tiel-Passewaaij site in the Netherlands. The soils were investigated using a range of techniques, including X-ray Fluorescence (XRF) spectroscopy, sequential soil extractions, Fourier-transformed infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD) and microprobe analysis. The results indicate that the studied soil features can chemically be distinguished from off-site soils e.g. based on their phosphate and carbonate content. Mineralogical analysis of aggregate samples from soil features further reveal that quartz and feldspar minerals are coated with Ca–Fe–P phases that closely resemble anapaite and mitridatite mineral forms. The formation of these mineral phases probably resulted from periodic reductive dissolution of Fe-oxide phases and subsequent precipitation of Fe–P phases, with inclusion of Ca from anthropogenic carbonates or groundwater. The combined presence of (Ca)-carbonates, P-phases and some anthropogenic trace elements (Cu, Zn) suggests that the greenish soil features stem from manure inputs.     

Clay mineralogy of archaeological soil: an approach to paleoclimatic and environmental reconstruction of the archaeological sites of the Paharpur area,Badalgacchi upazila,Naogaon district,Bangladesh

A geo-archaeological examination was carried out in and around the Paharpur area, Badalgacchi upazila of Naogaon District in the north-western part of Bangladesh. Clay mineralogy and global paleo-temperature curves were used to determine the paleoclimatic and depositional environmental conditions of the Holocene archaeological soils (Barind clay residuum) of the Paharpur archaeological spot. Clay mineralogical data show that the dominant clay mineral is illite with subordinate amounts of kaolinite and chlorite. The high illite and low kaolinite content implies a marine or estuarine deposit. The clay mineral ratio log diagram, constructed by plotting the 7–10°Å integrated intensity ratios versus depth, supports this assumption. The presence of illite, together with quartz and feldspar, suggests high detrital input under generally cool to temperate and dry climates. Chlorite is another common by-product of weathering reactions with low hydrolysis, which is typical for cool to temperate and dry climates. The results suggest the existence of a marine–estuarine influence under a generally cool to temperate and dry climates around Paharpur and the surrounding region throughout the Pala dynasty around mid-century 700 a.d. to early 1100 a.d. Furthermore, this observation is consistent with the global paleo-temperature curves.     

Algorithmic techniques of identifying discriminative ocean areas in oceanology problems

A problem of locating and comprehensively investigating ocean areas that exercise a significant influence over the migration dynamics of fishing ranks among important problems of fisheries oceanology. Among all the environment factors affecting various fishery situations, factors should be chosen that are constantly logged on large water areas for a long time comparable with fishery observation time. As described in a number of works, the most suitable information for these purposes is data on the distribution of surface temperature fields. The problem of locating discriminative areas can then be stated as follows. For a particular fishery situation (e.g., for the period of maximum catch in fishing season), temperature values or thermostructural features should be singled out that are suitable to define the situation, using hydrological charts of surface temperature fields. Correlating the feature with the areas where they were observed, we will obtain discriminative areas. The important problem is then to develop techniques and means for algorithmically identifying areas. This relates to a vast volume of information and complex structure. Logical-mathematical models of locating discriminative areas are being developed at the Pacific Oceanological Institute for some years. These models are to be for forecasting fishery situations in the NW Pacific. Techniques for representing isotherm fields in a computer have been developed. Formal operations of comparing the fields have been proposed which aid in distinguishing significant differences in their structure. A software for analyzing isotherm fields has been developed based on threshold logic models. This approach allows one not only to identify discriminative areas for relatively stable fishery situations but also to trace their dynamics. This has been achieved due to multiple-alternative computations and the presentations of data obtained in the form suitable for their interpretation. Some components of proposed models have been used in the system of short-term forecasting saira and sardine fishery in the South-Kuril area.     

岩土体水力学非线性问题

非线性问题是岩土体水力学研究的主要内容之一。将岩土体水力学非线性问题按非线性性质划分为以下7类:(1)渗流区域非线性问题(具有自由面的无压渗流);(2) 本构关系非线性问题(非达西渗流);(3) 渗透参数非线性问题(非饱和渗流);(4) 流态非线性问题(多相体渗流);(5) 介质非线性问题(多重介质渗流);(6) 相互作用非线性问题(渗流与溶质运移、温度、应力等耦合问题);(7) 多重非线性问题(上述两种或两种以上非线性问题的组合)。对这7类非线性问题的背景、特点、数学性质、解法、应用等方面进行系统的分析与归纳总结。可以看出,对非线性问题的继续深入研究必将推动岩土体水力学的进一步发展。     

A coupling method for soil structure interaction problems

This paper describes a soil‐structure coupling method to simulate blast loading in soil and structure response. For the last decade, simulation of soil behavior under blast loading and its interaction with semi buried structure in soil becomes the focus of computational engineering in civil and mechanical engineering communities. In current design practice, soil‐structure interaction analysis often assumes linear elastic properties of the soil and uses small displacement theory. However, there are numerous problems, which require a more advanced approach that account for soil‐structure interaction and appropriate constitutive models for soil. In simplified approaches, the effect of soil on structure is considered using spring‐dashpot‐mass system, and the blast loading is modeled using linearly decaying pressure–time history based on equivalent trinitrotoluene and standoff distance, using ConWep, a computer program based on semi‐empirical equations. This strategy is very efficient from a CPU time computing point of view but may not provide accurate results for the dynamic response of the structure, because of its significant limitations, mainly when soil behavior is strongly nonlinear and when the buried charge is close to the structure. In this paper, both soil and explosive are modeled using solid elements with a constitutive material law for soil, and a Jones–Wilkins–Lee equation of state for explosive. One of the problems we have encountered when solving fluid structure interaction problems is the high mesh distortion at the contact interface because of high fluid nodal displacements and velocities. Similar problems have been encountered in soil structure interaction problems. To prevent high mesh distortion for soil, a new coupling algorithm is performed at the soil structure interface for structure loading. The coupling method is commonly used for fluid structure interaction problems in automotive and aerospace industry for fuel sloshing tank, and bird impact problems, but rarely used for soil structure interaction problems, where Lagrangian contact type algorithms are still dominant. Copyright © 2012 John Wiley & Sons, Ltd.     

Scaling of transient wave–soil interaction problems

Within the framework of compressible multi‐phase flow through deformable porous media, wave–soil interactions in the near‐shore region during wave runup and drawdown are modeled. Critical non‐dimensional parameters governing the interaction processes are identified. Within the context of wave basin and centrifuge wave tank facilities, we propose scaling relations for the experimental investigations of the transient and steady‐state responses of wave–soil systems. Numerical simulations are conducted to illustrate and confirm the theoretical and scaling analyses. Based on the simulations results, the implications on the design of experiments and interpretation of results are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

浅谈土壤形态分析中存在的问题

通过对土壤样品形态分析实验及多件样品的分析,探讨了土壤样品粉碎制备和分析中存在的一些问题,并提出了有效的建议。