Acidity Control After Surface Application of Micronized Liming Material in a Typic Distrudept Under No-Tillage

Abstract The objected to evaluate the pH and soil base saturation (V) values, during 45 months after, surface application and without incorporation of the liming materials in deeper layers of soil. The experimental design was completely randomized blocks in split-plot with four replications. In the plots were studied the dolomitic limestone (DL) and micronized liming materials (MLM) - granulated micronized calcite (GMC) and dolomite (GMD), and carbonated suspension (CS). In the subplots were studied doses of all the liming materials aiming to increase V to 50, 70 and 90% besides of control treatment. We measured the pH and V values in 0-5, 5-10, 10-20, 20-40 and 40-60 cm soil layers over time (5, 15, 28, 37 and 45 months). The MLM were more efficient to increase and maintain the pH and V, over time, than DL. The doses of MLM aiming V to 50-70% increasing the pH and V of Typic Distrudept. Despite the MLM are more fineness than DL, the effectiveness for soil acidity control in subsoil were inefficient, because theses pH and V increases/maintains occurred just in 0-5 cm layer. However, the MLM present lower gap between the V estimated and obtained, in the 0-5 cm layer, than DL.

Aislamiento e Identificación de Hongos filamentosos tolerantes a aceites dieléctricos usados y los Bifenilos Policlorados (PCBs) de suelos contaminados / Isolation and Identification of Filamentous Fungi Tolerant to Used Dielectric Oils and Contaminated Soil Polychlorinated biphenyls (PCBs)

Los PCBs por sus propiedades físicas y químicas son usados en diferentes sectores industriales; sus productos de desechos y su almacenamiento inadecuado han contaminado ambientes como suelos y aguas poniendo en peligro la supervivencia en los ecosistemas. Sin embargo, algunos seres vivos son capaces de adaptarse. Los bifenilos policlorados (PCBs) son compuestos orgánicos de hidrocarburos sintéticos formados por dos anillos de benceno unidos por un enlace de carbono; comprenden una clase de 209 compuestos individuales, isómeros y congéneres. Su objetivo fue aislar e identificar hongos filamentosos capaces de tolerar y adaptarse para sobrevivir en condiciones adversas en el ecosistema suelo contaminado por el xenobiótico PCBs, presente en aceites dieléctricos usados (ADU) en un sector industrial de Barranquilla. Los hongos aislados de los géneros Aspergillus sp, Alternaría sp, Phoma sp, Rhizopus sp. sobrevivieron a concentraciones de ADU 20 %, y a 200 ppm de PCBs

PCBs for their physical and chemical properties are used in different industrial sectors; waste products and inadequate storage have polluted environments such as soils and water that endanger ecosystem survival. However, some living beings are able to adapt. Polychlorinated biphenyls (PCBs) are organic synthetic hydrocarbon compounds formed by two benzene rings bonded by a carbon bond, comprise a class of 209 individual compounds, isomers and congeners. Its objective was the isolation and identification of filamentous fungi capable of tolerating and adapting to survive in adverse conditions in the soil ecosystem contaminated by the xenobiotic PCBs, present in used dielectric oils (ADU) in an industrial sector of Barranquilla. The isolated fungi of the genus Aspergillus sp, Alternaria sp, Phoma sp, Rhizopus sp. survived concentrations of 20% ADU, and 200 ppm of PCBs.

Chemical and physical attributes and calcium, magnesium, potassium, and phosphorus in the soil of murundu fields in Brazil / Atributos químicos, físicos e estoque de cálcio, magnésio, potássio e fósforo em solos de campos de murundus no Brasil

Fields of murundus (FM) are wetlands that provide numerous ecosystem services. The objectives of this study were to evaluate the chemical [organic carbon (OC), P, K+, Ca2+, Mg2+, Al3+ and H+Al] and physical [texture and bulk density (Bd)] soil attributes and calculate the organic matter (OM) and nutrient stock (P, Ca, Mg, and K) in soils of FM located in the Guapore River basin in Mato Grosso. Thirty-six sampling points were selected, and soil samples were collected from two environments: the murundu and plain area surrounding (PAS). At each sampling point, mini trenches of 0.5 × 0.5 × 0.4 m were opened and disturbed and undisturbed soil samples were collected at depths of 0-0.1, 0.1-0.2, and 0.2-0.4 m. In the Principal Component Analysis the variables H+Al (49%) and OM (4%) were associated with the F1 component and sand content (47%) with the F2 component. The FM had lower pH values and higher concentrations of K+, P, and H+Al than PAS at all depths (p < 0.05). Additionally, FM stocked up to 433, 360, 205, and 11 kg ha-1 of Ca, Mg, K, and P, respectively, for up to a depth of 0.2 m. The murundu stored two times more K and three times more P than that in the PAS. Our results show that the FM has high sand content and Bd greater than 1.5 Mg m-3, high acidity, low OC content, and low nutrient concentrations. Thus, special care must be taken to preserve FM such that human intervention does not trigger environmental imbalances.

Campos de murundus (CM) são áreas úmidas que prestam inúmeros serviços ecossistêmicos. Os objetivos desse estudo foram avaliar atributos químicos [carbono orgânico (CO), P, K+, Ca2+, Mg2+, Al3+ e H+Al] e físicos [textura e densidade do solo (Ds)] e calcular os teores de matéria orgânica (MO) e estoques dos nutrientes P, Ca, K e Mg em solos de CM localizados na bacia do Rio Guaporé em Mato Grosso. Foram selecionados 36 pontos de amostragem e coletadas amostras de solo em dois ambientes: murundu e área plana circunvizinha (APC). Em cada ponto foram abertas minitrincheiras de 0,5 × 0,5 × 0,4 m e coletadas amostras de solo deformadas e indeformadas nas profundidades de 0-0,1; 0,1-0,2; e 0,2-0,4 m. Na Análise de Componentes Principais as variáveis H+Al (49%) e MO (4%) foram associados com o componente F1 e o teor de areia (47%) com o componente F2. O murundu apresenta menor pH e maiores teores de K+, P e H+Al que a APC em ambas profundidades (p < 0,05). Até 0,2 m esses CM estocam 433; 360; 205; e 11 kg ha-1 de Ca, Mg, K e P, respectivamente. No entanto, o murundu estoca duas vezes mais K e três vezes mais P que a APC. Estes CM apresentam altos teores de areia, Ds superior a 1,5 Mg m-3, elevada acidez, baixo teor de CO e pobreza em nutrientes. Dessa forma, necessitam de cuidados especiais para que a intervenção antrópica não desencadeie desequilíbrios ambientais.

A consideration of the mechanism for liquefaction-related large ground displacement

The authors discussed the mechanism of the liquefaction-related large ground displacement by referring the existing researches and an shaking table test result. Firstly, they reviewed the outcomes from case studies on large ground displacement during past earthquakes as well as empirical formulae proposed from regression analyses of the ground displacement with various factors such as gradient of ground surface, and studied fundamental characteristics of the large ground movement. Secondarily, the authors reviewed existing experimental works on ground displacement and on the mechanical properties of liquefaction soil during the ground movement. Furthermore, the authors conducted a shaking table test, where the ground surface was inclined after complete liquefaction of the soil. Based on the review of the existing researches and on the shaking table test they proposed an idea on the mechanism of the large ground displacement during liquefaction.(AU)

Ground motion characteristics and their relation to soil liquefaction at the wildlife liquefaction array, Imperial Valley, California

We use the earthquake shaking severity parameter Arias intensity, Ih, to assess the site specific characteristics of ground motion, and investigate the relation of those characteristics to soil liquefaction occurrence at the Wildlife liquefaction array, in response to the Elmore Ranch and Superstition Hills earthquakes of November 23 and 24, 1987.(AU)

Review of energy - based liquefaction research at case Western Reserve University

The development of pore pressure leading to liquefaction of soils subjected to earthquake loadings has been associated by several researches in recent years to the amount energy imparted to the soil during the dynamic motion. More recently, exploratory laboratory work conducted at Case Western Reserve University indicated that regardless of the mode of stress application, sinusoidal or random, the unit energy needed to initiate liquefaction is nearly constant for a given effective confining stress and a specific relative density. This work also demonstrated that the unit energy imparted to the soil to induced liquefaction is independent of the shear strain amplitude. Data obtained during torsional shear testa made possible the development of relationships between the unit energy required for liquefaction (as the dependent variable) and the effective confining pressure and the relative density(as the independent variables). This paper summarizes these significant developments, and includes preliminary results of tests conducted on soils that liquefied during the recent Northridge Earthquake (Lower San Fernando Valley Dam). The fundamentals of an energy-based method to determine the liquefaction potential of a soil deposit are also presented.(AU)

VELACS project : A summary of achievements

In a collaborative and unprecedentent effort, seven major universities from United States and England studied the liquefaction phenomena and its consequences by conducting extensive centrifuge tests on nine carefully selected centrifuge models. In addition, more than 20 groups of researchers from all over the world participated in a Class-A prediction exercise to predict the response of centrifuge models before they were conducted. This paper summarizes the lessons learned from the VELACS project in relation to repeatability of centrifuge models and perfomance of the existing numerical procedures in analyzing soil liquefaction and its consequences.(AU)

Preliminary evaluation of the use of compaction piles for improvement of the foundation soils of the coastal dikes of Lake Maracaibo, Venezuela

Recent studies have confirmed the liquefaction potential of the foundation soils of the coastal dikes of the Eastern Coast (Costa Oriental) of Lake Maracaibo, in western Venezuela, a region of moderate seismicity. Mitigative measures consisting of downstream berms, with or without compaction piles, are being implemented. To evaluate the effectiveness of compaction piles against liquefaction of the silty sands the improvement of low resistance clays, two field tests were perfomed, one in Bachaquero and one in Lagunillas. The 0.60m diameter, 13m long piles were implanted in an 8 row, 5 column arrangement, 3m on centers. A ground levelling network was established. Piezometers, accelerometers and inclinometers readings were taken before, during and after pile implantation. The results obtained to date have confirmed that the berm and the compaction piles improve the properties of both the sandy and clayey soils and are, therefore, a valid method to improve the seismic stability of the coastal dikes of Lake Maracaibo.(AU)

Shaking table tests on floatation of buried pipes due to liquefaction of backfill sands

Many manholes and sewage pipes were floated due to liquefaction during the 1993 Kushiro-oki earthquake in Japan. To study the mechanism of the floatation, several shaking table tests were carried out under several conditions of soil densities, specific gravities of pipes, water levels and diameters of pipes. Tests were also conducted on the model grounds in which a trench was excavated and then backfilled with loose sands. Test results show that the speed and the height of floatation are affected by soil density, the specific gravity of the pipe or manhole, water level, and width and depth of the trench.(AU)

Hollow cylinder cyclic torsional simple shear investigation of fine silty and clayed sands

A series of undrained hollow cylinder cyclic torsional simple shear test was condusted on saturated mixtures of fine uniform sand, silt, and plastic clay to investigate pore pressure generation characteristics and liquefaction resistance under loading designed to simulated horizontally polarized shear waves in an earthquake. Specimens 10.0 inches (25.4 cm.) tall, with inner and outer diameters of 8.0 and 10.0 inches (20.3 and 25.4 cm), respectively, were moist - compacted from four soil mixtures for which fines type and content were independently varied (AU)

Probabilistic evaluation of liquefaction potential at President Island, Menphis

The proposed method incorporates local site condition and regional seismicity in the evaluation of liquefaction potential of a site. In addition, uncertainties in seismic and site parameters can be easily included in the analysis.(AU)

Observed effects of testing conditions on the residual strength of loose, saturated sands at large strains

Undrained residual strengths (or "steady state" strengths) are useful in assessing the potential for large ground deformations in deposits of loose, saturated sands due to the strain-softening behavior of these materials in undrained loading. Extensive research over the past decade has raised numerous issues regarding the effects of various testing conditions on these strengths when measured in the laboratoey. In this paper, the authors present the results of a testing program which invetsigated the possible effects of consolidation stress level, the effective stress path during shearing, and the drainage conditions on the steady state strengths of Monterey #0 sand. The data suggests thatthe mode of deformation, or strain path during shearing, may be an important factor affecting the steady state strengths of cohesionless soils.(AU)

Post - liquefaction settlement of sand - mechanism and in situ evaluation

The mechanism causing the substantial settlement observed during and immediately after liquefaction in a centrifuge test is studied using resistivity measurements to characterize the soil structure. The permeability value at the point of initial liquefaction is shown to increase from the value at the initial state when the tortuosities and the pore shape factors at the appropriate states are used in the Kozeny Carman equation. The mechanism causing the substantial increase in settlement is considered to be due to the increase in permeability. The higher the permeability, the higher is the rate of settlement and the larger is the incremental settlement in each time step. In addition, the increase in permeability causes the liquefaction front to propagate upwards faster and therefore, the generation and dissipation processes affect a larger depth of the soil column during shaking, and hence, produces a larger settlement.(AU)

Modelling of the stress - strain behavior of liquefiable sands

The concept to use dynamic backbone curve in conjunction with the Masing criteria for the construction of unloading and reloading branches of the initial cyclic loop, and its extension to subsequent cyclic loading when the soil undergoes significant degradation due to pore water pressure buildup, is verified. To accurately describe the initial and subsequent cyclic stress-strain loops, the original Kondner and Zelasko hyperbolic model and a well known degradation model are modified. The hysteretic damping can also be described quite accurately by the same method. The invetsigation is based on the test results obtained on several different liquefiable sands. The modelling of one of these sands is presented in detail.(AU)

Experimental study on the uplift deformation of underground structures induced by soil liquefaction

Earthquake-induced soil liquefaction causes uplift deformation of lifeline facilities buried in saturated sand layers. This paper presents results of shaking table tests carried out to evaluate the uplift deformation of an underground structure with a rectangular section buried in liquefiable layers. In these tests, the thickness of a liquefiable layer below an underground structure and the size of a structure section are varied. The excess pore water pressures and the accelerations in liquefied ground models are measured. Furthermore, the deformation of liquefied sand layers surrounding the underground structure model is observed.(AU)

Analysis of liquefaction induced uplift of underground structures

Uplift of underground structures associated with soil liquefaction is currently explained with the force balance between buoyancy and gravity. This explanation is not adequate when the soil partially liquefies and retains some amount of shear resistance nor will it be useful when one intends to estimate amount of uplift due to soil liquefaction. In order to obtain a reasonable understanding on the mechanism of the uplift and a reasonable estimation procedure of the amount uplift, an effective stress analysis is conducted on a submerged tunnel in a loosely deposited sand. Results of the analysis indicate that a fundamental mechanism in producing deformation of soil and structure is the existence of static stress due to gravity and its release in accordance with deformation. In particular, the most important mechanism which governs the amount of the uplift of underground structures is the extension shear deformation of the soil below the structures.(AU)

Stability of the root plates of coniferous trees planted on surface water gley soils

This paper presents details of a field study on the dynamic loading of mature coniferous tree stems planted on saturated mineral soils. The trees examined were planted in a narrow shallow layer of soil which had been deposited on the ground surface as a result of ploughing a furrow, The root plates are extremely shallow and the main roots tend to grow along the deposited aerated layer of soil. The unsymmetrical radial distribution of the main roots and the shallow rrot plates can render the trees unstable. In windly conditions the soil in the root plates can fail and as a result the trees can be blown over. This phenomenon is common in Ireland and in the United Kingdom and results in economic loss (AU)