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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Sedimentation and Consolidation of cohesive and non-cohesive soils formed under turbulent flows

Almabruk, Adam January 2018 (has links)
Settling and consolidation of suspended clay particles are significant issue in many fields such as geotechnical engineering, coastal and hydraulic engineering, and environmental engineering. A comprehensive literature review was conducted on the settling, consolidation and erosion of mixed soil material (cohesive and non-cohesive). Soil beds formed by sedimentation process of loose particles will be either show a segregated or homogeneous in structure, depending on the depositional environment. These sediments initially undergo self-weight consolidation and may be eroded under high flow rate. A number of studies have recently investigated the characteristic of consolidated clay bed in stagnant water. Hence, consolidation parameters were determined using a well-known vertical settling column consolidation test setup. However, limited research studies are available for deposition and consolidation of a mixture of sediment (clay, silt and sand) under flow conditions which are more representative of what happens in nature. A long flume and pump were used to create different turbulent conditions and simulate the natural process... The results for deposition and consolidation of different mixtures under stagnant and turbulence conditions were analyzed and compered in term of compressibility, permeability as well as shear strength. The results of this experimental research program indicated that the flow rate, initial concentration, height of settling and composition of sediment are all important factors that could affect the final bed dry unit weight. Two non-intrusive techniques were applied for measuring the dry unit weight at settling and consolidation stages. Impact echo technique has never been applied to measure the dry unit weight of self-weight consolidation along the vertical stratification of cohesive and non-cohesive particles. Also, a novel conductance sensor has been developed to improve the efficiency of this technique. The limitations of using these techniques will be highlighted in this study.
2

Numerical Study of Abutment Scour in Cohesive Soils

Chen, Xingnian 16 January 2010 (has links)
This research is part of the extension of the SRICOS-EFA method for predicting the maximum scour depth history around the bridge abutment. The basic objective is to establish the equation for predicting the maximum bed shear stress around the abutment at the initial condition of scouring. CHEN3D (Computerized Hydraulic ENgineering program for 3D flow) program is utilized to perform numerical simulations and predict bed shear stress before scouring. The Chimera technique incorporated in CHEN3D makes the program capable of simulating all kinds of complex geometry and moving boundary. CHEN3D program has been proven to be an accurate method to predict flow field and boundary shear stress in many fields and used in bridge scour study in cohesive soils for more than ten years. The maximum bed shear stress around abutment in open rectangular channel is studied numerically and the equation is proposed. Reynolds number is the dominant parameter, and the parametric studies have been performed based on the dimensional analysis. The influence of channel contraction ratio, abutment aspect ratio, water depth, abutment shape, and skew angle has been investigated, and the corresponding correction This research is part of the extension of the SRICOS-EFA method for predicting the maximum scour depth history around the bridge abutment. The basic objective is to establish the equation for predicting the maximum bed shear stress around the abutment at the initial condition of scouring. CHEN3D (Computerized Hydraulic ENgineering program for 3D flow) program is utilized to perform numerical simulations and predict bed shear stress before scouring. The Chimera technique incorporated in CHEN3D makes the program capable of simulating all kinds of complex geometry and moving boundary. CHEN3D program has been proven to be an accurate method to predict flow field and boundary shear stress in many fields and used in bridge scour study in cohesive soils for more than ten years. The maximum bed shear stress around abutment in open rectangular channel is studied numerically and the equation is proposed. Reynolds number is the dominant parameter, and the parametric studies have been performed based on the dimensional analysis. The influence of channel contraction ratio, abutment aspect ratio, water depth, abutment shape, and skew angle has been investigated, and the corresponding correction factors have been proposed. The study of the compound channel configuration is conducted further to extend the application of the proposed equation. Numerical simulations of overtopping flow in straight rectangular channel, straight compound channel and channel bend have been conducted. The bridge deck is found to be able to change the flow distribution and the bed shear stress will increase significantly once overtopping. The influence of the channel bend curvature, abutment location in the channel bend, and the abutment shape is also investigated. The corresponding variation of the bed shear stress has been concluded. The scour models, including the erosion rate function, roughness effect, and the turbulence kinetic energy, have been proposed and incorporated into the CHEN3D program. One flume test case in NCHRP 24-15(2) has been simulated to determine the parameters for the roughness and the turbulence kinetic energy. The prediction of the maximum scour depth history with the proposed model is in good agreement with the measurement for most cases. The influence of overtopping flow on the abutment scour development is also studied and the corresponding correction factor is proposed.
3

Some Studies On The Interfacial Friction Between Soils And Solid Surfaces

Robinson, R G 06 1900 (has links) (PDF)
No description available.
4

Efeito do Uso sobre a Coesão de Solo Cultivado com Cana- de- Açúcar em Tabuleiro Costeiro de Pernambuco

Lira, Rodolfho de Aquino 09 July 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-15T15:13:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação-RODOLFHO.pdf: 972823 bytes, checksum: c6ed8f08ace41c1927e4fd841d1b0cc4 (MD5) / Made available in DSpace on 2016-04-15T15:13:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação-RODOLFHO.pdf: 972823 bytes, checksum: c6ed8f08ace41c1927e4fd841d1b0cc4 (MD5) Previous issue date: 2015-07-09 / FACEPE / Os tabuleiros costeiros ocupam uma extensa área no litoral brasileiro e devido a seu relevo plano favorável à mecanização, precipitação pluvial alta e proximidade com os grandes centros consumidores, são as áreas de uso agrícola mais intensificado. Os solos predominantes nessa área são em geral, profundos, de baixa fertilidade natural e muitas vezes ocorrem com uma camada adensada, configurando os solos coesos. Esta coesão tem afetado propriedades físicas, químicas e hídricas do solo, que interferem diretamente no estabelecimento do cultivo e, consequentemente, na produtividade das culturas e renda dos agricultores. Os agricultores, em situações como esta, muitas vezes tendem a desmatarem mais áreas para cultivo, visando compensar perdas econômicas, causando impactos ambientais. O objetivo deste estudo foi avaliar o efeito do uso, sobre a resistência no horizonte coeso, em solos sob manejo de cana-de-açúcar e mata nativa, na unidade geoambiental dos Tabuleiros Costeiros de Pernambuco, a partir de ensaios físico-hídricos. Foram abertos um perfil em área de plantio de cana-de-açúcar e um em mata nativa, e coletadas amostras estruturadas do horizonte coeso. Os atributos físicos avaliados foram: Porosidade Total (macro, meso, micro e criptoporosidade), densidade do solo (Ds), curva característica de retenção de água no solo (CCRAS) e resistência do solo à penetração de raízes (RP). As médias dos parâmetros físicos analisados foram submetidas à análise de variância (ANOVA) e para os parâmetros que apresentam diferenças significativas foi aplicado o teste de Tukey, por meio do aplicativo SAS. A resistência à penetração foi um atributo eficiente para avaliar coesão dos solos estudados. Os manejos distintos não apresentaram diferença significativa nos valores de densidade Ds. A área cultivada apresentou maior capacidade de retenção de água, avaliada pelas curvas características de retenção, evidenciando que o manejo influenciou no tamanho dos poros. Na área de mata poderá ocorrer maior secamento do solo, sem que haja valores restritivos de resistência à penetração, pois precisará de um menor valor de umidade para que não haja impedimentos ao desenvolvimento do sistema radicular. / The costal plains occupates an extensive area in brazilian’s litoral and due to its plain relief suitable to mechanization, high pluvial precipitation and proximity with the big consumer centers, are intensified agricultural areas. The predominant soils in this area are in general, deep, of low natural fertility and most of the times occur with a condensed layer, setting the cohesive soils. This cohesion has affected physical, chemical and hydrous properties of the soil, which interfere directly in the settlement of the cultivation and, consequently, in the crops productivity and income of the farmers. The farmers, in situations like this, many times tend to deforest more areas to cultivation, aiming to compensate economic losses, causing environmental damage. The goal of this study was to evaluate the effect of the use in the resistance of the cohesive horizon, on soils under management of sugar cane and native forest in the geo environmental unit of the coastal plains of Pernambuco, from hydrous physical tests. It was opened a profile in the sugarcane area and another native forest, structured and collected samples of cohesive horizon. The assessed physical attributes were: Total porosity (macro, meso, micro and criptoporosidade), bulk density (Ds), water retention curve characteristic in the soil (CCRAS) and soil resistance to root penetration (RP). The average of the physical parameters analyzed were subjected to analysis of variance (ANOVA) and to the parameters that show significant differences was used the Tukey test, using the SAS software. The penetration resistance was an effective attribute to evaluate the cohesion of soils studied. The different managements showed no significant difference in density values Ds. The crapped area presented higher water holding capacity, when evaluated by retention curves, showing that the management influenced the pore size. In forest area may occur more soil drying, without restrictive values of penetration resistance because need a lower moisture value so there are no impediments to the development of the root system.
5

Vibro-driveability -a field study of vibratory driven sheet piles in non-cohesive soils

Viking, Kenneth January 2002 (has links)
No description available.
6

Vibro-driveability -a field study of vibratory driven sheet piles in non-cohesive soils

Viking, Kenneth January 2002 (has links)
No description available.
7

Numerical and experimental studies of shallow cone penetration in clay

Hazell, Edmund January 2008 (has links)
The fall-cone test is widely used in geotechnical practice to obtain rapid estimates of the undrained shear strength of cohesive soil, and as an index test to determine the liquid limit. This thesis is concerned with numerical modelling of the penetration of solids by conical indenters, and with interpretation of the numerical results in the context of the fall-cone test. Experimental studies of shallow cone penetration in clay are also reported, with the aim of verifying the numerical predictions. The practical significance of the results, in terms of the interpretation of fall-cone test results, is assessed. Results are reported from finite element analyses with the commercial codes ELFEN and Abaqus, in which an explicit dynamic approach was adopted for analysis of continuous cone indentation. Quasi-static analyses using an elastoplastic Tresca material model are used to obtain bearing capacity factors for shallow cone penetration, taking account of the material displaced, for various cone apex angles and adhesion factors. Further analyses are reported in which a simple extension of the Tresca material model, implemented as a user-defined material subroutine for Abaqus, is used to simulate viscous rate effects (known to be important in cohesive soils). Some analyses with the rate-dependent model are displacement-controlled, while others model the effect of rate-dependence on the dynamics of freefall cone indentation tests. Laboratory measurements of the forces required to indent clay samples in the laboratory are reported. Results from displacement-controlled tests with imposed step-changes in cone speed, and from freefall tests, confirm that the numerical rate-dependent strength model represents the observed behaviour well. Some results from experiments to observe plastic flow around conical indenters are also presented. Finally, additional numerical analyses are presented in which a critical state model of clay plasticity is used to study the variation of effective stress, strain and pore pressure around cones in indentation tests at various speeds.
8

Efeitos de diferentes preparos nos atributos físicos do solo e no desempenho produtivo do mamoeiro Tainung 01 / Effects of different tillage systems on physical attributes of soil and productive performance of papaya Tainung 01

Zuffo, Valmir José 25 April 2012 (has links)
Made available in DSpace on 2016-12-23T13:23:23Z (GMT). No. of bitstreams: 1 Valmir Jose Zuffo.pdf: 1368477 bytes, checksum: 44171d69a24efae303b1240c27505ebc (MD5) Previous issue date: 2012-04-25 / Avaliaram-se os efeitos de cinco sistemas de preparo do solo nos atributos físicos de um Argissolo Amarelo coeso de Tabuleiro, bem como no crescimento, desenvolvimento e nutrição do mamoeiro Formosa Tainung 01 irrigado. O experimento foi instalado em 21/01/2011 e conduzido a campo por 260 dias, em área anteriormente utilizada com pastagem de Brachiaria nunca corrigida ou fertilizada, irrigada por sistema de aspersão de baixa pressão. Os tratamentos, implantados em cinco repetições e em delineamento de blocos ao acaso foram: 1) grade aradora (duas vezes) + niveladora + camalhão sobre a linha confeccionado 135 após transplantio (GA c/ CAM); 2) grade aradora (duas vezes) + niveladora (GA s/ CAM); 3) subsolador florestal (SF); 4) grade aradora (duas vezes) + niveladora + escarificação com 3 hastes sobre a linha de plantio (GA + ELP); 5) grade aradora (duas vezes) + niveladora + escarificação com 3 hastes em área total (GA + EAT). Os preparos receberam sulcamento mecanizado e banquetas, confeccionadas manualmente com terra solta do sulco, que foram niveladas e fertilizadas para receber as mudas. Antes da implantação dos tratamentos a área experimental foi caracterizada quanto à resistência mecânica à penetração (RP) acompanhada pela umidade do solo, diâmetro médio ponderado (DMP), diâmetro médio geométrico (DMG), densidade do solo (Ds), macroporosidade (Ma), microporosidade (Mi), relação Ma/Mi, textura do solo e fertilidade. Após a implantação dos tratamentos foram determinadas RP, acompanhada pela umidade do solo, DMP, DMG, Ds, Ma, Mi, relação Ma/Mi e variáveis biométricas de nutrição e produção como altura de plantas, diâmetro do tronco a 0,20 m de altura, altura de inserção do primeiro fruto, sexo das plantas, teores foliares de macro e micronutrientes bem como número de frutos por planta com separação de frutos comerciais e não comerciais. O tratamento estatístico dos dados constou de cálculo do erro padrão da média para os dados de RP e para os demais dados, análise de variância e teste de Tukey a nível de 5% de probabilidade. Houve diferenças de resistência à penetração entre os tratamentos. O subsolador mostrou-se mais efetivo na diminuição da RP até 0,35 m de distância da planta no sentido transversal à linha de plantio. O escarificador resultou em menores RP do que GA ou SF, mesmo a 0,40 m de profundidade, e foi mais eficiente a maiores distâncias transversalmente à planta. Todos os preparos provocaram RP menores do que 2,5 MPa na profundidade de maior concentração de raízes do mamoeiro (0 0,25 m) fornecendo boas condições físicas até essa profundidade. Não houve diferença estatística entre os tratamentos para Ds, Ma, Mi, relação Ma/Mi, DMP e DMG a 0,20 m de profundidade e teores foliares de macro e micronutrientes aos 197 dias após transplantio. A altura de plantas em duas épocas foi menor para o SF e igual estatisticamente para os outros tratamentos. A grade aradora alterou os atributos físicos do solo em maior intensidade até 0,20 m de profundidade. A produção total de frutos e de frutos comerciais foi maior nos preparos GA c/ CAM, GA s/ CAM, GA+ELP e GA+EAT, os quais não diferiram entre si. Não houve diferenças para produtividade de frutos não comerciais. Não se justificou o uso do camalhão sobre a linha de plantio confeccionado após o transplantio. Do ponto de vista de conservação do solo, quando considerados os dados de estabilidade de agregados, os preparos foram semelhantes. A relação entre o crescimento e desenvolvimento das plantas e diferentes preparos de solo deve ser avaliada considerando o conjunto de atributos físicos e químicos do solo / The effects of five tillage systems on soil physical attributes, growth, development and nutrition of Formosa papaya Tainung 01 were evaluated on cohesive Alfisol of Coastal Tableland. The experiment was planted on january 21, 2011 and remained in field for 260 days, in an area previously used with Brachiaria never corrected nor fertilized before and irrigated by low pressure sprinkler system. Treatments were applied in five replicates and statistical design of random blocks were: 1) heavy disc harrow (twice) + offset disc harrow + ridge on row planting made 135 days after transplanting (GA c/ CAM); 2) heavy disc harrow (twice) + offset disc harrow (GA s/ CAM); 3) forester subsoiler (SF); 4) heavy disc harrow (twice) + offset disc harrow + chisel plow on row planting (GA+ELP); 5) heavy disc harrow (twice) + offset disc harrow + chisel plow on total area (GA+EAT). All tillage systems received mechanized furrower and a bench made with loose soil and fertilizers and over which the seedlings were planted. As a characterization of experimental area before application of treatments, were determined penetration resistance (RP) followed by soil moisture, mean weight diameter (DMP), geometric mean diameter (DMG), bulk density (Ds), macroporosity (Ma), microporosity (Mi), Ma/Mi ratio, soil texture and fertility. After application of treatments were determined RP, accompanied by soil moisture, DMP, DMG, Ds, Ma, Mi and Ma/Mi ratio and biometric variables of nutrition and production as plant height, stem diameter at 0,20 m height, height of insertion of the first fruit, plant sex, foliar contents of macro and micronutrients as well as number of fruits per plant with separation of commercial and non-commercial ones. Statistical treatment of data included calculation of mean standard error for RP and analysis of variance for all other data accompanied by the Tukey test for comparison of means at 5% level of probability. There were differences in penetration resistance between treatments. Subsoiler showed to be more effective in the decrease of RP up to 0,35 m away from the plant in the direction transverse to the rows. Chisel plow produced smaller RP than GA or SF, even at 0,40 m depth and was more effective at greater distances from the plant. All tillage systems produced RP smaller than 2.5 MPa at a depth with the greater concentration of papaya roots (0 0.25 m) and provided good physical conditions up to this depth. There was no statistical difference between treatments for Ds, Ma, Mi, Ma/Mi ratio, DMP e DMG at 0.20 m depth and foliar contents of macro and micronutrients at 197 days after transplanting. Height of plants in two stages were lower for the SF and statistically equal to the other treatments. Heavy disc harrow altered soil physical attributes at a higher intensity up to 0.20 m depht. Total fruit yield and commercial fruit yield was higher in GA c/ CAM, GA s/ CAM, GA+ELP and GA+EAT, which did not differ. There were no differences for non-commercial fruit yield. There was no justification for the building of the ridge on the planting row after instalation of the orchard. From the standpoint of conservation of soil, when considering the stability of aggregates data, all tillage systems were similar. The relationship between growth and development performance of plants and tillage systems should be evaluated considering whole physical and chemical properties of soil
9

Comportamento mecânico de um Latossolo Amarelo Distrocoeso não saturado sob diferentes sistemas de manejo culturais da cana-de-açúca

VASCONCELOS, Romero Falcão Bezerra de 17 February 2009 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-17T13:58:22Z No. of bitstreams: 1 Romero Falcao Bezerra de Vasconcelos.pdf: 1209446 bytes, checksum: 5d0e80152c5bbb339e575d66b8691373 (MD5) / Made available in DSpace on 2016-08-17T13:58:23Z (GMT). No. of bitstreams: 1 Romero Falcao Bezerra de Vasconcelos.pdf: 1209446 bytes, checksum: 5d0e80152c5bbb339e575d66b8691373 (MD5) Previous issue date: 2009-02-17 / The soils of the Coastal Plains cultivated with sugarcane for a long period of time under different management systems may make changes in physical and chemical properties and the state of soil aggregation. Considering the above, the objective of this study was to evaluate the effects of different management systems with sugarcane on the chemical and physical properties of a dystrophic cohesive Yellow Latosol of coastal tablelands of Alagoas. Plots were selected in areas of production in the growing of sugarcane, and the object of experimental research three areas, representative of three management systems adopted by sugarcane production unit, namely: a cultivated area under irrigation management system (SMI), an area under the management system of fertirrigation with vinasse (SMV) and area under a management system with application of vinasse + filter tart (SMVT). These management systems were compared and on the witness pattern represented by native forest (NF). To assess the physical and chemical properties and aggregation state of the soil, the soil samples were collected at random in the areas subject to different management systems, in the depths of 0- 0,20; 0,20-0,40 and 0,40-0,60 m, being withdrawn at a point between the lines of sugarcane. The results were submitted to analysis of variance and the averages compared by Tukey test to 5% significance. Study of simple correlations were performed between some variables measures. The results showed that the different management systems promoted investigated changes in physical and chemical properties and the state of soil aggregation. The parameters of consistency of the soil tended to increase the humidity in their values with the increase of total organic carbon (TOC) of soil, promoted by the addition of waste from sugar cane. The studies of simple correlations between the total organic carbon (TOC) and the rates of stability of aggregate investigated, showed significant (p<0,01) correlation and positive. The management systems that received the addition of waste from sugarcane showed less deterioration in physical and chemical properties of soil in the soil under native forest (NF). / Os solos dos tabuleiros costeiros cultivados com cana-de-açúcar, durante longo período de tempo, sob diferentes sistemas de manejo, podem apresentar alterações nas propriedades físicas e químicas e no estado de agregação. O objetivo do trabalho foi avaliar os efeitos de diferentes sistemas de manejo com cana-de-açúcar sobre as propriedades físicas e químicas de um Latossolo Amarelo Distrocoeso dos tabuleiros costeiros de Alagoas. Foram selecionadas áreas em talhões de produção com a cultura da cana-de-açucar, sendo objeto de pesquisa experimental três áreas, representativas de três sistemas de manejo adotados pela unidade sucroalcooleira, a saber: uma área cultivada sob sistema de manejo irrigado (SMI), uma área sob sistema de manejo de fertirrigação com vinhaça (SMV) e uma área sob sistema de manejo com aplicação de vinhaça + torta de filtro (SMVT). Esses sistemas de manejo foram comparados entre si e em relação a uma testemunha padrão, representada por uma mata nativa (MN). Para avaliar as propriedades físicas e químicas e o estado de agregação do solo, amostras de solo foram coletadas ao acaso, nas áreas submetidas aos diferentes sistemas de manejo, nas profundidades de 0-0,20; 0,20-0,40 e 0,40-0,60 metros, sendo retiradas num ponto situado nas entrelinhas da cana-de-açúcar. Os resultados obtidos foram submetidos a análise de variância e as médias comparadas pelo teste de Tukey, a 5% de significância. Estudos de correlações simples foram realizados entre algumas variáveis medidas. Os resultados permitiram concluir que os diferentes sistemas de manejo investigados promoveram alterações nas propriedades físicas e químicas e no estado de agregação do solo. Os parâmetros de consistência do solo apresentaram tendência de aumento em seus valores de umidade com o incremento do carbono orgânico total (COT) do solo, promovido pela adição de resíduos da cana-de-açúcar. Os estudos de correlações simples entre o carbono orgânico total (COT) e os índices de estabilidade de agregados investigados apresentaram correlações significativas (p<0,01) e positivas. Os sistemas de manejo que receberam adição de resíduos da cana-de-açúcar denotaram menor degradação nas propriedades físicas e químicas do solo, em relação ao solo sob mata nativa (MN).
10

Parâmetros físico-ambientais para compartimentação geoambiental e delimitação da ocorrência de solos coesos na depressão do São Francisco, BA / Physical and environmental parameters for geoenvironmental and delimitation subdivision of occurrence of cohesive soils in depression of San Francisco, BA

Santos, Joildes Brasil 02 September 2014 (has links)
Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-15T19:16:42Z No. of bitstreams: 2 Dissertação - Joides Brasil dos Santos - 2014.pdf: 5701209 bytes, checksum: 23a5a3d1ab6539ee0f3d63efa7031d9e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-16T11:04:42Z (GMT) No. of bitstreams: 2 Dissertação - Joides Brasil dos Santos - 2014.pdf: 5701209 bytes, checksum: 23a5a3d1ab6539ee0f3d63efa7031d9e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-16T11:04:42Z (GMT). No. of bitstreams: 2 Dissertação - Joides Brasil dos Santos - 2014.pdf: 5701209 bytes, checksum: 23a5a3d1ab6539ee0f3d63efa7031d9e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-09-02 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Studies on cohesive soils in Brazil and worldwide indicate that cohesion in the soil is a factor of natural limitation to agricultural use. However, in the region of the Coastal Tablelands in Northeast Brazil these soils are used through use and management techniques adapted to their natural limitations, such as high resistance to penetration, hard when dry and friable when moist, with high density and reduced effective depth, depending of dense horizon. As for the cohesion process in the soil, would be related to the accumulation clay soil filling the pores and increase its density, making them more resistant to penetration of roots. The silicification process could also be related to the formation of cohesive horizon because that silica is one of the principal cementing agents in this process in various regions of the planet. In addition, climate alternating between dry season and wet season this would also enhance soil compaction. In this study we discuss the presence of soils with cohesive horizon in Oxisols and Ultisols Yellow Yellows geomorphological unit called Depression of the San Francisco-BA, focusing on the area of the snail farm that featured a soil survey in detail. From a geo-environmental partitioning was presented a summary with the main features of the landscape, in order to understand the environment in which this type of soil occurs. And with the help of physical and environmental parameters of the relief (hipsometria, slope and curvature of the sides), use and vegetation and soil properties (isovalue of clay and silica content), it was possible to create a map with the location of the area with potential occurrence of cohesive soils for Farm Caracol, which certainly extends outside its boundaries. / Estudos sobre solos coesos no Brasil e no mundo apontam que a coesão no solo é um fator de limitação natural à utilização agrícola. Entretanto, na região dos Tabuleiros Costeiros no Nordeste Brasileiro esses solos são utilizados mediante técnicas de uso e manejo adaptados às suas limitações naturais, como alta resistência a penetração, duro quando secos e friáveis quando umedecidos, com alta densidade e profundidade efetiva diminuída, em função de horizonte adensado. Quanto ao processo de coesão no solo, estaria relacionado ao acúmulo de argila preenchendo os poros do solo e aumentando sua densidade, tornando-os mais resistentes à penetração de raízes. O processo de silicificação também poderia ser relacionado à formação do horizonte coeso, pois que a sílica é um dos principais agentes cimentantes nesse processo em várias regiões do planeta. Em adição, a alternância climática entre estação seca e estação úmida também intensificaria esse adensamento do solo. Nesta pesquisa é discutida a presença de solos com horizonte coeso em Latossolos Amarelos e Argissolos Amarelos da Unidade Geomorfológica denominada Depressão do São Francisco-BA, com foco na área da Fazenda Caracol que contou com um levantamento de solos em detalhe. A partir de uma compartimentação geoambiental foi apresentada uma síntese com as principais características físicas da paisagem, com o objetivo de entender o ambiente em que esse tipo de solo ocorre. E com auxílio de parâmetros físico-ambientais do relevo (hipsometria, declividade e curvatura das vertentes), do uso e vegetação e alguns atributos do solo (isovalores dos teores de argila e sílica), foi possível criar um mapa com a localização da área com potencial de ocorrência dos solos coesos para a Fazenda Caracol, a qual certamente se prolonga para fora de seus limites.

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