Study of the foundations, bearing soil and stability of the minaret-tower of Cordobas Mosque

This research in Cordoba's mosque tower main objective was to analyze and characterize the foundations and the underlying soil, calculating the stability of the monument as well as the settlement and deformations performed, using traditional calculation methods and also by finite elements, and to determine differences between both, as well as the stability factor of the Minaret Tower. The works done to study the soil, were drill bores and dynamic penetration tests, classification of samples by size, Atterberg limits, physical and chemical analysis, showing the typical geotechnical composition of the Guadalquivir valley: an alluvial material composed by sand, gravels and silt clays. To study the foundations, inclined bore samples were extracted with 10-65º, showing calcarenite stone ashlars and lime concrete alternating with stone and brick masonry.

Ca-amendement and tillage: medium term synergies for improving key soil properties of acid soils. Soil and tillage research, 134: 195-206

Ca-amendments are routinely applied to improve acid soils, whilst no-tillage (NT) has been widely recommended in soils where traditional tillage (TT) has led to losses of organic matter. However, the potential interactions between the two treatments are only partially known. Our study was conducted on an annual forage crop agrosystem with a degraded Palexerult soil located in SW Spain, in order to assess if the combination of NT plus a Ca-amendment provides additional benefits to those of their separate use. To this end we analysed the effects of four different combinations of tillage and Ca-amendment on selected key soil properties, focusing on their relationships. The experimental design was a split-plot with four replicates. The main factor was tillage (NT versus TT) and the second factor was the application or not of a Ca-amendment, consisting of a mixture of sugar foam (SF) and red gypsum (RG). Soil samples were collected from 3 soil layers down to 50 cm after four years of treatment (2009). The use of the Ca-amendment improved pH and Al-toxicity down to 25 cm and increased exchangeable Ca2+ down to 50 cm, even under NT due to the combined effect of SF and RG. Both NT and the Ca-amendment had a beneficial effect on total organic carbon (TOC), especially on particulate organic carbon (POC), in the 0–5 cm layer, with the highest contents observed when both practices were combined. Unlike NT, the Ca-amendment failed to improve soil aggregation in spite of the carbon supplied. This carbon was not protected within the stable aggregates in the medium term, making it more susceptible to mineralization. We suggest that the fraction of Al extracted by oxalate from solid phase (AlOxa-Cu-K) and the glomalin-related soil proteins (GRSPs) are involved in the accumulation of carbon within water stable aggregates, probably through the formation of non-toxic stable Al-OM compounds, including those formed with GRSPs. NT alone decreased AlK in the 0–5 cm soil layer, possibly by increasing POC, TOC and GRSPs, which were observed to play a role in reducing Al toxicity. From our findings, the combination of NT and Ca-amendment appears to be the best management practice to improve chemical and physical characteristics of acid soils degraded by tillage.

Soil aggregate geometry: Measurements and morphology

Aggregates provide physical microenvironments for microorganisms, the vital actors of soil systems, and thus play a major role as both, an arena and a product of soil carbon stabilization and dynamics. The surface of an aggregate is what enables exchange of the materials and air and water fluxes between aggregate exterior and interior regions. We made use of 3D images from X-ray CT of aggregates and mathematical morphology to provide an exhaustive quantitative description of soil aggregate morphology that includes both intra-aggregate pore space structure and aggregate surface features. First, the evolution of Minkowski functionals (i.e. volume, boundary surface, curvature and connectivity) for successive dilations of the solid part of aggregates was investigated to quantify its 3D geometrical features. Second, the inner pore space was considered as the object of interest. We devised procedures (a) to define the ends of the accessible pores that are connected to the aggregate surface and (b) to separate accessible and inaccessible porosity. Geometrical Minkowski functionals of the intra-aggregate pore space provide the exhaustive characterization of the inner structure of the aggregates. Aggregates collected from two different soil treatments were analyzed to explore the utility of these morphological tools in capturing the impact on their morphology of two different soil managements, i.e. conventional tillage management, and native succession vegetation treatment. The quantitative tools of mathematical morphology distinguished differences in patterns of aggregate structure associated to the different soil managements.

Química da matéria orgânica e pedogênese em Latossolos húmicos sob vegetação de cerrado

A matéria orgânica do solo (MOS) representa um importante reservatório de carbono (C) nos ecossistemas terrestres. O conteúdo de C estocado no solo pode ser liberado para a atmosfera na forma de CO2, com a decomposição da MOS, ou pode ser aumentado com a entrada de resíduos e retenção da MOS. Nesse sentido, é importante entender os mecanismos de estabilidade e retenção da MOS para predizer como os solos respondem a mudanças, quer sejam elas induzidas por alterações climáticas ou por práticas de manejo. Dentro dos Latossolos, classe que ocupa cerca de 32 % do território brasileiro, há aqueles que possuem horizonte A húmico hiper espesso e, portanto, com maior estoque de C. Aspectos sobre a origem, formação e preservação do horizonte A húmico destes solos em suas ocorrências em diferentes biomas ainda não foram completamente elucidados e estão estritamente ligados à fonte, dinâmica e mecanismos de preservação e distribuição da MOS no solo. O objetivo deste trabalho é entender a gênese da MO dos Latossolos húmicos que ocorrem no Bioma Cerrado, por meio da caracterização molecular pela técnica da pirólise acoplada à cromatografia gasosa e espectroscopia de massas (pirólise - CG/EM). Para isso, foram coletadas amostras dos horizontes A em dois perfis de Latossolos com horizonte A húmico (LH1, LH2) e um perfil de Latossolo com horizonte A moderado (solo de referência; LNH) situados em superfície de aplanamento adjacente à Serra do Espinhaço, no município de Grão Mogol - MG, sob clima tropical semi-úmido e vegetação de cerrado sensu strictu. Por meio da descrição morfológica dos solos em diferentes níveis de observação (campo, lupa e microscópio) procurou-se entender melhor os mecanismos de espessamento do horizonte A e a distribuição de partículas de carvão ao longo do perfil. As amostras dos horizontes foram submetidas ao fracionamento físico e extração da MOS, gerando as seguintes frações: fração leve livre (FLL); fração leve oclusa (FLO), fração extraível com NaOH (EXT) e resíduo (RES). A morfologia dos perfis evidencia a intensa e longa atividade biológica (fauna e raízes) a que esses solos foram e estão submetidos. Isso explica a abundância de microagregados e a consequente macropososidade elevada, assim como a ampla distribuição de fragmentos de carvão em todo o horizonte A, e parte do B, com dimensões milimétricas a submilimétricas, sugerindo a fragmentação destes ao longo do tempo. Foi evidenciado o maior conteúdo de carvões nos dois LHs em comparação ao LNH. A distribuição da MOS nas frações estudadas foi a mesma para os três perfis estudados: RES>EXT>FLL>FLO, que mostra a importância da fração RES para estes solos. Produtos da carbonização (Black carbon; BC: hidrocarbonetos poliaromáticos) foram mais abundantes na fração RES e FLO, no entanto, a maior diferença qualitativa entre a MOS de LHs e LNH diz respeito à abundância de BC na fração RES, que é maior em LHs do que LNH; confirmando a maior quantidade de carvões em LHs verificada na morfologia. Um índice de degradação do BC foi estabelecido com base em análise fatorial com os todas as frações estudadas e produtos poliaromáticos. Este índice, aplicado às frações EXT e RES, mostrou que a degradação do BC aumenta com a profundidade/idade, e não houve diferenças significativas entre os perfis estudados. Portanto, LHs provavelmente tem maior entrada de carvões, o que deve estar ligado a um histórico de maior incidência de incêndios ou maior abundância local de espécies arbóreas.

Influência do tamanho da amostra na determinação da curva de retenção da água no solo

A curva de retenção da água no solo é um dos principais instrumentos para avaliar a qualidade física dos solos e possibilitar seu manejo adequado. Por meio da Teoria da Capilaridade vários equipamentos foram desenvolvidos para determinar a intensidade com que a água está retida ao solo, porém, pouco se tem dado atenção para verificar se os pressupostos para o real funcionamento da teoria estão sendo atendidos. Um aspecto refere-se ao tamanho da amostra utilizada para determinar a curva de retenção, de modo que haja continuidade dos feixes capilares na amostra e placa porosa. Desta forma, este trabalho propõe avaliar diferentes tamanhos de amostra indeformada para a determinação da curva de retenção. Para isso, coletaram-se amostras em anéis volumétricos cilíndricos de três tamanhos (altura) diferentes (T1 - 0,075 m; T2 - 0,05 m; T3 - 0,025 m;) e mesmo diâmetro interno (0,07 m), dos horizontes diagnósticos de um Latossolo e um Nitossolo em áreas experimentais da Escola Superior de Agricultura Luiz de Queiroz (Esalq/USP), Piracicaba - SP. Realizou-se a caracterização física destes solos, por meio da análise granulométrica, densidade do solo, densidade de partículas, porosidade total e teor de carbono orgânico. As curvas foram determinadas para cada tamanho de amostra, utilizando-se o Funil de Haines, para as tensões 0,5, 1, 4, 6 e 10 kPa, e a Câmara de Pressão de Richards para 33, 100 e 500 kPa. As curvas de retenção foram ajustadas pelo modelo utilizado por van Genuchten. Estimadas as curvas, avaliou-se a distribuição de poros do solo das amostras, determinando-se a curva de frequência acumulada de poros em função do logaritmo do raio e, depois pela diferenciação das equações de ajuste das curvas de retenção, a curva diferencial de frequência acumulada de poros. Os resultados mostram que o Latossolo, por ter textura arenosa no horizonte estudado, não apresentou diferença significativa nas curvas de retenção para os tamanhos das amostras estudadas. Verificou-se pouca modificação na distribuição dos poros deste solo, que possui teor elevado das frações areia fina e muito fina, e desenvolveram papel importante para a retenção de água. O Nitossolo, por sua vez, apresentou diferença significativa da curva obtida pela amostra de menor tamanho (T3), havendo maior retenção de água com a diminuição do tamanho da amostra. Devido a sua textura muito argilosa, o arranjo estrutural deste solo foi diferenciado ao se utilizar as amostras maiores, com provável interrupção e descontinuidade dos feixes capilares. Consequentemente, houve também alteração na distribuição dos poros, com redução dos mesoporos e aumento dos microporos. Desta forma, pode-se concluir que o tamanho da amostra influenciou a curva de retenção da água devido à complexidade estrutural do solo, que provavelmente é diferente nas amostras maiores por causa da continuidade dos feixes capilares, principalmente no Nitossolo. Em outras palavras, quanto menor o tamanho da amostra há menor diferenciação no arranjo de poros, ou seja, maior proximidade da real condição do solo e, assim, uma interpretação da retenção de água \"mais correta\" por meio da Teoria da Capilaridade.

Evaluating the Effectiveness of Post Fire Emergency Rehabilitation Treatments on Soil Degradation and Erosion Control in Semi-Arid Mediterranean Areas of the Spanish South East

In this study, we seeded a native plant species and applied a mulch of chopped wood originating from the same burned area to avoid the establishment of invasive species. We evaluated four treatments: (1) seeding, (2) mulch, (3) seeding and mulch, and (4) control. Our objective was to increase plant recovery and to minimize the soil erosion and degradation. The study was conducted in Alicante, Spain in Torremanzanas forest of the semi-arid Mediterranean bioclimatic area after the wildfire of November, 2002. During three years of monitoring, we find that combined treatment: seeding and mulch increased the post fire plant recovery 20% approximately more than the rest of treatments and the control plots. We also found that seven months after treating mulch and seeding and mulch treatments presented a gain of soil: +5.18 to + 5.24 mm while the seeding treatment and control plots presented soil loss rates of: −0.48 to −0.49 mm. In addition, mulch treatment significantly decreased soil compaction to the half, and increased the infiltration capacity to 40 ml.mn−1 more than in plots without mulch, as well as increased the soil respiration to the double compared with no mulch plots. Work in progress confirms the positive effect of chopped wood as mulching treatment with or without seeding on the soil protection against soil erosion, and the amelioration of bio-physical properties after wildfires in the Mediterranean semi-arid burned areas.

New Approaches for Teaching Soil and Rock Mechanics Using Information and Communication Technologies

Soil and rock mechanics are disciplines with a strong conceptual and methodological basis. Initially, when engineering students study these subjects, they have to understand new theoretical phenomena, which are explained through mathematical and/or physical laws (e.g. consolidation process, water flow through a porous media). In addition to the study of these phenomena, students have to learn how to carry out estimations of soil and rock parameters in laboratories according to standard tests. Nowadays, information and communication technologies (ICTs) provide a unique opportunity to improve the learning process of students studying the aforementioned subjects. In this paper, we describe our experience of the incorporation of ICTs into the classical teaching-learning process of soil and rock mechanics and explain in detail how we have successfully developed various initiatives which, in summary, are: (a) implementation of an online social networking and microblogging service (using Twitter) for gradually sending key concepts to students throughout the semester (gradual learning); (b) detailed online virtual laboratory tests for a delocalized development of lab practices (self-learning); (c) integration of different complementary learning resources (e.g. videos, free software, technical regulations, etc.) using an open webpage. The complementary use to the classical teaching-learning process of these ICT resources has been highly satisfactory for students, who have positively evaluated this new approach.

Redistribution of Soil Organic Matter by Permafrost Disturbance in the Canadian High Arctic

With increased warming in the Arctic, permafrost thaw may induce localized physical disturbance of slopes. These disturbances, referred to as active layer detachments (ALDs), redistribute soil across the landscape, potentially releasing previously unavailable carbon (C). In 2007–2008, widespread ALD activity was reported at the Cape Bounty Arctic Watershed Observatory in Nunavut, Canada. Our study investigated organic matter (OM) composition in soil profiles from ALD-impacted and undisturbed areas. Solid-state 13C nuclear magnetic resonance (NMR) and solvent-extractable biomarkers were used to characterize soil OM. Throughout the disturbed upslope profile, where surface soils and vegetation had been removed, NMR revealed low O-alkyl C content and biomarker analysis revealed low concentrations of solvent-extractable compounds suggesting enhanced erosion of labile-rich OM by the ALD. In the disturbed downslope region, vegetation remained intact but displaced material from upslope produced lateral compression ridges at the surface. High O-alkyl content in the surface horizon was consistent with enrichment of carbohydrates and peptides, but low concentrations of labile biomarkers (i.e., sugars) suggested the presence of relatively unaltered labile-rich OM. Decreased O-alkyl content and biomarker concentrations below the surface contrasted with the undisturbed profile and may indicate the loss of well-established pre-ALD surface drainage with compression ridge formation. However, pre-ALD profile composition remains unknown and the observed decreases may result from nominal pre-ALD OM inputs. These results are the first to establish OM composition in ALD-impacted soil profiles, suggesting reallocation of permafrost-derived soil C to areas where degradation or erosion may contribute to increased C losses from disturbed Arctic soils.

Physical models of dilatant normal faulting in jointed cohesive rocks

Dilatant faults often form in rocks containing pre-existing joints, but the effects of joints on fault segment linkage and fracture connectivity is not well understood. We present an analogue modeling study using cohesive powder with pre-formed joint sets in the upper layer, varying the angle between joints and a rigid basement fault. We analyze interpreted map-view photographs at maximum displacement for damage zone width, number of connected joints, number of secondary fractures, degree of segmentation and area fraction of massively dilatant fractures. Particle imaging velocimetry helps provide insights on deformation history of the experiments and illustrate the localization pattern of fault segments. Results show that with increasing angle between joint-set and basement-fault strike the number of secondary fractures and the number of connected joints increases, while the area fraction of massively dilatant fractures shows only a minor increase. Models without pre-existing joints show far lower area fractions of massively dilatant fractures while forming distinctly more secondary fractures.

Laboratories approved to receive soil /

Description based on: July 1992; title from cover.

Physical land conditions in Clarke county, Georgia,

In pamphlet box with 19 additional folded maps.

The physical properties of soils.

At head of title: Soil mechanics laboratory manual.

Lime-modified soil to increase subgrade stability /

"May 1983."

Synthesis dataset of physical and ecosystem properties from pan-arctic wetland sites using peat core analysis

Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, C/N ratio) and C accumulation rates among vegetation types and environmental classes.

Determining Spatial Distribution and Physical Properties of the Vashon Advance Outwash near Mountlake Terrace, Washington

This study is aimed at determining the spatial distribution, physical properties, and groundwater conditions of the Vashon advance outwash (Qva) in the Mountlake Terrace, WA area. The Qva is correlative with the Esperance Sand, as defined at its type section; however, local variations in the Qva are not well-characterized (Mullineaux, 1965). While the Qva is a dense glacial unit with low compressibility and high frictional shear strength (Gurtowski and Boirum, 1989), the strength of this unit can be reduced when it becomes saturated (Tubbs, 1974). This can lead to caving or flowing in excavations, and on a larger scale, can lead to slope failures and mass-wasting when intersected by steep slopes. By studying the Qva, we can better predict how it will behave under certain conditions, which will be beneficial to geologists, hydrogeologists, engineers, and environmental scientists during site assessments and early phases of project planning. In this study, I use data from 27 geotechnical borings from previous field investigations and C-Tech Corporation’s EnterVol software to create three-dimensional models of the subsurface geology in the study area. These models made it possible to visualize the spatial distribution of the Qva in relation to other geologic units. I also conducted a comparative study between data from the borings and generalized published data on the spatial distribution, relative density, soil classification, grain-size distribution, moisture content, groundwater conditions, and aquifer properties of the Qva. I found that the elevation of the top of the Qva ranges from 247 to 477 ft. I found that the Qva is thickest where the modern topography is high, and is thinnest where the topography is low. The thickness of the Qva ranges from absent to 242 ft. Along the northern, east-west trending transect, the Qva thins to the east as it rises above a ridge composed of Pre- Vashon glacial deposits. Along the southern, east-west trending transect, the Qva pinches out against a ridge composed of pre-Vashon interglacial deposits. Two plausible explanations for this ridge are paleotopography and active faulting associated with the Southern Whidbey Fault Zone. Further investigations should be done using geophysical methods and the modeling methods described in this study to determine the nature of this ridge. The relative density of the Qva in the study area ranges from loose to very dense, with the loose end of the spectrum probably relating to heave in saturated sands. I found subtle correlations between density and depth. Volumetric analysis of the soil groups listed in the boring logs indicate that the Qva in the study area is composed of approximately 9.5% gravel, 89.3% sand, and 1.2% silt and clay. The natural moisture content ranges from 3.0 to 35.4% in select samples from the Qva. The moisture content appears to increase with depth and fines content. The water table in the study area ranges in elevation from 231.9 to 458 ft, based on observations and measurements recorded in the boring logs. The results from rising-head and falling-head slug tests done at a single well in the study area indicate that the geometric mean of hydraulic conductivity is 15.93 ft/d (5.62 x 10-03 cm/s), the storativity is 3.28x10-03, and the estimated transmissivity is 738.58 ft2/d in the vicinity of this observation well. At this location, there was 1.73 ft of seasonal variation in groundwater elevation between August 2014 and March 2015.