The presence of parasitic structures in sandy soil samples from beaches located along the north coast of Rio Grande do Sul, Brazil

Beaches are a source of parasite contamination because protozoan cysts and helminth eggs and larvae can remain viable in sandy soils for months. Parasitic infections are mainly related to hygiene conditions, health, and environmental education, and can affect the life quality of the population. Therefore, this study aimed to assess the presence of parasitic structures in five beaches located along the north coast of Rio Grande do Sul, Brazil. Eighty samples were collected in August and September 2020 at the beaches of Torres, Tramandaí, Capão da Canoa, Arroio Teixeira, and Arroio do Sal and processed with the spontaneous sedimentation method for microscopic analyses. The results showed that 32% (26/80) of samples were positive for the presence of parasitic structures, and there was a significantly higher frequency of positive samples in September than in August. Torres was the beach with the highest frequency of positive samples, while Arroio Teixeira and Arroio do Sal presented the lowest frequency of contamination. Nematode larvae, including hookworm larvae, were the most prevalent parasitic structures in the samples. Hence, the sandy soil from beaches must be monitored to develop programs and strategies for improving infrastructures and basic sanitation conditions, thus ensuring the health of the population.

Parasitic contamination in the soil of beaches from Mosqueiro Island, Pará State, Brazil / Contaminação parasitária no solo de praias da Ilha do Mosqueiro, Estado do Pará, Brasil

Objective: We aimed to evaluate the prevalence of intestinal parasitic in the soil of three beaches of Mosqueiro Island, located in the State of Pará, Brazil, as well as to compare the frequency of helminths and protozoa, pathogenic and non-pathogenic parasites according to the beaches analyzed. Methods: This is a cross-sectional analytical study conducted during August and September 2019, in which 155 soil samples were analyzed by Hoffman's method. Results: The results showed that 16.1% of samples were contaminated from 61.3% of collection points. Murubira beach and Farol beach presented the highest prevalence of parasites, however, there was no significant difference between beaches. Also, it was observed a predominance of protozoa (63%) and non-pathogenic parasites (55.6%) in analyzed samples, but there was no statistically significant difference according to the investigated location. Endolimax nana 25.9% (7/27) and hookworms 18.5% (5/27) were the most detected parasites on the beaches. Conclusion: Thus, this study showed parasitic contamination on the beaches from Mosqueiro Island, which may be associated with a lack of sanitation infrastructure and personal hygiene in these places. Therefore, these results reinforce the need to adopt educational and preventive measures to reduce parasitic agents.

Objetivo: Avaliar a prevalência de parasitos intestinais no solo de três praias da Ilha de Mosqueiro, localizada no estado do Pará, Brasil, além de comparar a frequência de helmintos e protozoários, parasitos patogênicos e não patogênicos de acordo com as praias analisadas. Metdodos: Este é um estudo transversal, analítico, realizado durante agosto e setembro de 2019, no qual 155 amostras do solo foram analisadas pelo método de Hoffman. Resultados: Os resultados revelaram que 16,1% das amostras estavam contaminadas em 61,3% dos pontos de coleta. As praias do Murubira e do Farol apresentaram a maior prevalência de parasitos, porém não houve diferença significativa entre os diferentes locais de coleta. Além disso, foi observada a predominância de protozoários (63%) e parasitas não patogênicos (55.6%) nas amostras analisadas, mas não houve diferença estatística significativa entre os locais investigados. Endolimax nana 25,9% (7/27) e Ancilostomídeos 18,5% (5/27) foram os parasitas mais detectados nas praias. Conclusao: Desse modo, este estudo mostrou contaminação parasitária nas praias da Ilha de Mosqueiro, o que pode estar associada à falta de infraestrutura de saneamento e higiene pessoal nesses locais. Além disso, esses resultados reforçam a necessidade de se adotar medidas educacionais e preventivas para a redução desses agentes parasitários.

Increasing the Productive Potential of an Ultisol using Cover Crops and Organic and Mineral Fertilization

Abstract The occupation of sandy soils in Brazil has occurred with poor adoption of management technology, which has caused its degradation. The recovery of organic matter, particularly when growing annual plants and cover crops, with mulch residue allows the maintenance of the productive potential of these soils. Thus, the shoot dry mass production (SDMP) of winter cover crops was evaluated in an Ultisol under no-tillage system and in rotation with soybean and maize using 0, 2, 4 and 8 t ha-1 year-1 of poultry litter, mineral fertilizer exclusively and 2 t ha-1 year-1 of poultry litter associated with a half-dose of mineral fertilizer. The experimental design included randomized blocks with four replicates. The use of poultry litter increased the SDMP of the cover crops; the production was relatively high when high doses of poultry litter were applied; on the other hand, the yield of SDMP and grain was limited by the exclusive use of mineral fertilizer. Organic matter and nutrient status improvement by cover crops were one of the reasons for the increase in soybean and maize grain yields.

Establecimiento y evaluación de dos métodos de pre tratamiento de muestras de suelo para la extracción de ADN para el estudio de la diversidad bacteriana / Establishment and evaluation of two methods of pre-treatment of soil samples for the extraction of DNA for the study of bacterial diversity

La necesidad de ampliar los conocimientos respecto a los mecanismos bioquímicos y fisiológicos desarrollados por los microorganismos presentes en suelos requiere de una descripción completa de la diversidad microbiana, para lo cual en las últimas décadas se han desarrollado diferentes técnicas moleculares (qPCR, DGGE, T-RFLP, RAPD.) las mismas que requieren una adecuada técnica de extracción de ADN que aseguren el éxito de la descripción de la diversidad microbiana, considerando las características de las muestras de suelos a ser estudiadas. Los protocolos de extracción de ADN generalmente utilizados están basados en la separación de los microorganismos de la matriz antes de la extracción de ADN mediante lisis física o química y por otro lado, la extracción directa del ADN microbiano a partir de muestras de suelo, sin embargo la presencia de sustancias húmicas y fenólicas afectan la calidad del ADN extraído, lo que repercuten en el desarrollo de posteriores estudios moleculares. La finalidad de este estudio fue la de establecer procedimientos de pre tratamientos de 3 tipos de nuestras de suelo (arenoso, arcilloso y francos) para posteriormente describir la riqueza y diversidad bacteriana de las muestras en estudio mediante PCR DGGE. De esta manera se determinó que la adición de CaCO3 en muestras de suelos francos permite la identificación de una mayor diversidad y riqueza bacteriana (10 bandas). Asimismo, la adición de PVPP a suelos arenosos (8 bandas) y arcillosos (3 bandas) también permite obtener las características descritas anteriormente utilizando el método PCR-DGGE. Lo cual indica que los procedimientos de pre tratamiento con CaCO3 y PVPP son específicos para la extracción de ciertas comunidades microbianas.

The knowledge about biochemical and physiological mechanisms by microorganisms in soils are required for a complete description of microbial diversity, lately different molecular techniques have been developed to study this feature (qPCR, DGGE, T- RFLP, RAPD). DNA extraction techniques ensure the description of the microbial diversity success, according the soil samples characteristics. Generally, DNA extraction protocols used for separation of microorganism of matrix soil before DNA extraction by physical and chemical lysis. Other protocol is direct extraction of microbial DNA from soil samples, humic acids and phenolic substances affect the quality of DNA, which affect the development of subsequent molecular studies. The purpose of this study was to establish pretreatment procedures for different kind of soil samples (frank, sandy and clayey) in order to describe richness and bacterial diversity by PCR DGGE. In this sense, we determined the addition of CaCO3 in frank soils samples allows the identification of greater diversity and bacterial richness (10 bands) than the other method. Besides, PVPP pretreatment is no only useful to obtain bacterial diversity in sandy soil (8 bands), but also in clayey soils (3 bands) soils by PCR-DGGE method. This indicates that the pretreatment procedures with CaCO3 and PVPP are specific for soil microbial community's isolation.

Impact or push-off lameness presentation is not altered by the type of track surface where horses are trotted / Claudicação de impacto ou elevação não é alterada pelo tipo de superfície onde os cavalos são troteados

This study aimed to evaluate the influence of the track surface on which horses are examined, regarding the phase of lameness presentation. Ten horses with lameness in at least one limb were evaluated with wireless inertial sensors on three track surfaces (concrete, loose sand and grass). Six crossover track sequences were established. The variables vector sum, maximum and minimum height of the head and pelvis, variation coefficient of the maximum and minimum height of the head and pelvis were analyzed using ANOVA, followed by Tukey test to compare means between track surface and sequence, at 5% significance level. The lameness phase (impact or pushoff) was analyzed considering the proportion of affected animals. There were no differences on vector sum, maximum and minimum height or variation coefficient of head and pelvis. Difference was observed on the number of strides registered on sand compared to grass and concrete (p <0.0001) for fore and hindlimbs. Impact lameness on forelimbs was presented by a larger number of animals on the concrete surface; pushoff lameness was more evident on the grass surface. In the hindlimbs, impact lameness was more evident on the grass surface, while pushoff lameness was in greater number of animals on concrete surfaces. The track sequence on which horses were trotted during evaluation does not seem to be a factor, but the number of lame horses and the phase of lameness manifestation can vary between track surfaces, as some horses showed impact lameness on soft ground and elevation lameness on hard ground.

Este estudo teve como objetivo avaliar a influência do tipo de superfície em que os cavalos são examinados em relação à fase de apresentação da claudicação. Dez cavalos com claudicação em pelo menos um dos membros foram avaliados com sensores inerciais sem fio em três tipos de superfície (concreto, areia e grama). Seis sequências de cruzamento de tipo de superfície foram estabelecidas. As variáveis soma vetorial, altura máxima e mínima da cabeça e da pélvis, o coeficiente de variação da altura máxima e mínima da cabeça e da pélvis foram analisadas utilizando uma Análise de Variância, seguida do teste de Tukey para comparação das médias entre tipos de superfície e sequências, a um nível de significância de 5%. A fase da claudicação (impacto ou elevação) foi analisada considerando a proporção de animais afetados. Não houve diferença na soma vetorial, altura máxima ou mínima e coeficiente de variação da altura máxima e mínima da cabeça e pélvis. Foi observada diferença no número de passos registrados na areia em comparação com grama e concreto (p <0,0001) para membros torácicos e pélvicos. Claudicação de impacto nos membros torácicos foi apresentada em um número maior de animais na superfície de concreto, já claudicação de elevação foi mais evidente na superfície de grama. Em membros pélvicos, a claudicação de impacto foi mais evidente na superfície de grama, enquanto claudicação de elevação esteve em maior número de animais na superfície de concreto. A sequência de superfícies em que os cavalos foram troteados durante a avaliação não foi um fator importante na manifestação da claudicação, mas o número de cavalos claudicantes e a fase de manifestação da claudicação podem variar entre as superfícies, visto que alguns cavalos mostraram claudicação de impacto em solo macio e claudicação de elevação em solo duro.

Avaliação de dois tratamentos de adubação em plantio de eucalipto clonal em solo arenoso / Evaluation of two fertilization treatments in clonal eucalypt plantation in sandy soil

Este trabalho foi realizado com finalidade de testar o efeito de um composto organo-mineral sobre o rendimento, em madeira, de um clone de eucalipto. O experimento constituiu-se, portanto, em três tratamentos: (i) adubação mineral praticada pela empresa (WM), em termos de calagem e adubações; (ii) a mesma adubação mineral adotada nos plantios da referida Empresa, acrescido do composto organo-mineral (VZ) e (iii) um tratamento referência, representado pela condição original (Cerradão ­ CE). Os incrementos nutricionais ao solo foram avaliados em comparação com o solo de uma área adjacente, ainda sob vegetação original. As amostragens para análises de fertilidade do solo foram realizadas dezoito meses após o plantio e foram retiradas até a profundidade de dois metros, com duas repetições em cada tratamento: WM, VZ e CE. Os resultados das análises químicas demonstraram que, de um modo geral, a melhoria na fertilidade do solo sob plantio de eucalipto foi mais expressiva no tratamento que recebeu o composto organo-mineral. Os cálculos para avaliar o incremento de madeira foram realizados 30 meses após o plantio. Constatou-se, com os cálculos de cubagem, um potencial incremento significativo na produção de madeira no tratamento com adição do composto organomineral, com ganho de 72,41 m3 ha-1 aos sete anos, em relação ao tratamento WM. Além de, um lucro líquido de, aproximadamente, R$ 1.499,42 por hectare.

This study evaluated the effect of an organo-mineral fertilizer on wood yield of a eucalypt clone. The experiment consisted of three treatments: (i) the one regularly used by the company, in terms of liming and fertilization (WM), (ii) the same chemical fertilization, plus the organo-mineral fertilizer (VZ) and a reference treatment, represented by the original condition (Savannah vegetation ­ CE). Nutritional increments to the soil were evaluated in comparison to the soil of an adjacent area, still under original vegetation. The samples for soil fertility analyses were taken eighteen months after planting, down to a depth of two meter, with two repetitions in each treatment: WM, VZ and Savannah (CE). Evaluation of wood increment was done 30 months after planting. The results of the chemical analyses demonstrated that, in general, improvement in soil fertility in the eucalypt planting was greater in the treatment receiving the organo-mineral fertilizer. The determination of solid volume indicated a significant increase in wood production in the treatment with the addition of the organo-mineral fertilizer, with a projected gain of 72.41 m3 ha-1 after seven years, in relation to the standard treatment (WM). Moreover, the estimated net profit was, approximately, R$ 1,499.42 per hectare.

Disponibilidade de fósforo em solos com diferentes texturas após aplicação de doses crescentes de fosfato monoamônico de liberação lenta / Phosphorus availability in soils with different textures after application of growing doses of slow release monoammonium phosphate

A disponibilidade de P no solo é dependente do seu teor de argila, quanto maior o seu teor e o tempo de permanência do P no solo, maior sua adsorção e menor sua disponibilidade. O uso de fontes de liberação lenta podem aumentar esta disponibilidade, uma vez que o revestimento impede o contado do fertilizante com os óxidos, diminuindo sua adsorção. O experimento foi conduzido no Laboratório de análises de fertilidade do solo CeFert, localizado no Campus do Centro Universitário de Patos Minas, em Minas Gerais. Objetivou-se quantificar os teores de P disponível, após incubação de solos com diferentes texturas. Os tratamentos foram testemunha (sem aplicação de P) e doses crescentes de P2O5 (50; 100; 200 e 400 mg dm-3), utilizando o fosfatado monoamônico de liberação controlada, em solo argiloso, médio e arenoso. Avaliou-se o P disponível aos 30, 60 e 90 dias da incubação do fertilizante com o solo. Os resultados demonstraram que o solo argiloso apresentou maior disponibilidade do nutriente quanto maior a dose aplicada.

The availability of P in soil is dependent on its clay content, the higher degree and permanence of soil P, the greater its absorption and lower availability. The use of slow-release sources may increase this availability, since the coating prevents the counting of the fertilizer with the oxides, thus reducing their adsorption. The experiment was conducted in the laboratory of analysis of soil fertility CeFert, located on the campus of the Centro Universitário de Patos Minas, in Minas Gerais. The objective was to quantify the levels of available P after incubation of soils with different textures. The treatments were control (no P application) and increasing doses of P2O5 (50, 100, 200 and 400 mg dm-3), monoammonium phosphate using controlled release, in clay soil, sandy medium. We assessed P available 30, 60 and 90 days incubation of the fertilizer with soil. The results showed that the clay soil had a higher nutrient availability as the doses applied.

The nematicidal effect of some bacterial biofertilizers on Meloidogyne incognita in sandy soil

In a greenhouse experiment, the nematicidal effect of some bacterial biofertilizers including the nitrogen fixing bacteria (NFB) Paenibacillus polymyxa (four strains), the phosphate solubilizing bacteria (PSB) Bacillus megaterium (three strains) and the potassium solubilizing bacteria (KSB) B. circulans (three strains) were evaluated individually on tomato plants infested with the root-knot nematode Meloidogyne incognita in potted sandy soil. Comparing with the uninoculated nematode-infested control, the inoculation with P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2, increased the counts of total bacteria and total bacterial spores in plants potted soil from 1.2 to 2.6 folds estimated 60 days post-inoculation. Consequently, the inoculation with P. polymyxa NFB7 increased significantly the shoot length (cm), number of leaves / plant, shoot dry weight (g) / plant and root dry weight (g) / plant by 32.6 percent, 30.8 percent, 70.3 percent and 14.2 percent, respectively. Generally, the majority treatments significantly reduced the nematode multiplication which was more obvious after 60 days of inoculation. Among the applied strains, P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2 inoculations resulted in the highest reduction in nematode population comparing with the uninoculated nematode-infested control. They recorded the highest reduction in numbers of hatched juveniles/root by 95.8 percent, females/root by 63.75 percent and juveniles/1kg soil by 57.8 percent. These results indicated that these bacterial biofertilizers are promising double purpose microorganisms for mobilizing of soil nutrients (nitrogen, phosphate and potassium) and for the biological control of M. incognita.

Estaquia de Ginkgo biloba L. utilizando três substratos / Ginkgo biloba L. cutting using three substrates

Ginkgo biloba é arbórea, decídua, cuja folhagem se torna amarelada no outono antes da queda das folhas, o que a torna valorizada em jardinagem. A estaquia é um método de propagação vegetativa baseado na capacidade das células em retomarem o processo de divisão celular, formando raízes em estacas destacadas de ramos provenientes de plantas matrizes. O presente trabalho teve como objetivos verificar a influência de diferentes substratos, assim como, a aplicação da auxina sintética o ácido indol butírico (AIB) no enraizamento de estacas de Ginkgo biloba. No inverno de 2005, ramos foram coletados e transportados até o Laboratório de Macropropagação, onde foram confeccionadas estacas sem folhas, com 10-12 cm de comprimento. Os tratamentos com regulador vegetal (T) foram T1- 0 mg L-1 AIB em solução; T2- 4000 mg L-1 AIB em solução; T3- 8000 mg L-1 AIB em solução; T4- 0 mg kg-1 AIB em talco; T5- 4000 mg kg-1 AIB em talco e T6- 8000 mg kg-1 AIB em talco. Para cada tratamento foram utilizados três diferentes substratos (S), S1- areia, S2- fibra de casca de coco (coxim) e S3- casca de arroz carbonizada. Após 120 dias da instalação, foram avaliadas as porcentagens de estacas enraizadas, vivas, com calos e mortas; o número de raízes por estaca e o comprimento das três maiores raízes por estaca. Os melhores resultados no enraizamento foram obtidos com estacas tratadas com 4000 e 8000 mg kg-1 AIB em talco, utilizando o coxim como substrato (45,00 e 46,25 por cento de enraizamento, respectivamente).

Ginkgo biloba is an arboreal and deciduous species, the foliage of which becomes yellowish in the autumn, before leaf drop, increasing its value for gardening. Cutting is a method of vegetative propagation based on the capacity of cells to recover the cell division process, originating roots in cuttings detached from branches of stock plants. This study aimed to verify the influence of different substrates, as well as the application of the synthetic auxin indole-3-butyric acid (IBA) in Ginkgo biloba cutting rooting. In the winter of 2005, branches were collected and sent to the Macropropagation Lab, where cuttings of 10-12cm length were made without leaves. The treatments with plant growth regulator (T) were T1- 0 mg L-1 IBA solution, T2- 4000 mg L-1 IBA solution, T3- 8000 mg L-1 IBA solution, T4- 0 mg kg-1 IBA in talc, T5- 4000 mg kg-1 IBA in talc, T6- 8000 mg kg-1 IBA in talc. Each treatment was planted in three substrates (S), S1- sand, S2- coir and S3- carbonized rice hull. After 120 days, the percentages of cuttings that were rooted, alive, with callus and dead were evaluated, besides the number of roots per cutting and the length of the three highest roots per cutting. The best results regarding rooting were obtained for cuttings treated with 4000 and 8000 mg kg-1 IBA in talc, by using coir as substrate (45.00 and 46.25 percent rooting, respectively).

Evaluación de mezclas formuladas de fertilizantes con dosis crecientes y aplicación de materia orgánica en el rendimiento de tabaco negro en un suelo arenoso bajo condiciones de invernadero / Evaluation of formulated blending of fertilizers with increasing doses and addition of organic matter in dark tobacco in a sandy soil under greenhouse conditions

El presente trabajo compara tres mezclas formuladas de fertilizantes - una mezcla tradicional; un fertilizante mineral 10-15-20; y un fertilizante orgánico-mineral 8-12-16 en dosis crecientes , con y sin aplicación de materia orgánica (humus de lombriz) - en el cultivo de tabaco. El experimento se condujo en un suelo para cada dosis de NPK en mg.kg-1/maceta fue: dosis baja (160-60-80), dosis media (320-120-160) y dosis alta (480-180-240). Se utilizó el diseñó completo al azar con arreglo factorial, con tres repeticiones y conducido en macetas con 4 kg de suelo. La evaluación consistió en medir el rendimiento en peso fresco de la parte aérea y el peso seco total (parte aérea y radicular) de las plantas. Fue posible observar que no existe superioridad en cuanto a la materia fresca y seca total producidas entre las mezclas formuladas utilizadas, con un promedio de 432,5g/maceta y 112,6g/ maceta, respectivamente. Se pudo tener así tres alternativas en la fertilización de tabaco. Sin embargo, con el uso del fertilizante orgánico-mineral se obtendría mayores beneficios en el suelo por el efecto residual que dejaría por contener en su composición un 25 por ciento de materia por cada 100 kg de fertilizante. Conforme aumentan las dosis de fertilización se incrementan también los rendimientos, notándose el efecto directo de los fertilizantes en el sustrato arenoso utilizado, sin salinidad que pueda haber afectado la asimilación de nutrientes. Además, se observó la baja fertilidad del sustrato al comparar el tratamiento adicional 0-0-0 con los demás tratamientos, lo que ha producido más del 300 por ciento en cuanto a rendimiento. No existe efecto significativo en la interacción fertilizante vs. materia orgánica en la producción de materia fresca aérea y seca total, debido a que la dosis de materia orgánica fue baja (1 por ciento).

Evaluación del efecto de fertilización, aplicación de estiércol y absorción de elementos en el rendimiento de la secuencia papa-kiwicha, evaluado mediante la técnica del elemento faltante / Evaluation the effect of fertilization, application of manure and nutrient uptake in the yield of the sequence potato-kiwicha, evaluated using the omitted element technique

El presente trabajo evalúa el efecto de la fertilización al suelo, incorporación de estiércol y fertilización foliar de los elementos N, P, K, Mn y Zn, los cuales fueron evaluados mediante la técnica del elemento faltante. El experimento se condujo en un suelo de textura tipo arena de la Costa central del Perú y se usaron como plantas indicadoras los cultivos de papa y kiwicha, este último para evaluar el efecto residual de cada uno de los tratamientos. La fertilización al suelo para cada elemento en mg kg-1 fue de 200 = N, P2O5 y K2O; 50 = MgO y Fe; 25 = Mn y Zn. Se utilizó el diseño completo al azar con arreglo factorial, con tres repeticiones y conducido en macetas de 4 kg de suelo. La evaluación consistió en medir el rendimiento de materia seca total y absorción total de nutrientes analizados en los tejidos de la papa y kiwicha. Con la incorporación de 25 t/ha estiércol es posible suplir los requerimientos nutricionales de los elementos Fe, Mn y Zn para el cultivo de la papa; así mismo, mediante este procedimiento se puede suplir parcialmente los requerimientos de K y Mg y de manera muy limitada los de P y N. En la kiwicha el tratamiento completo mostró ligera depresión en su rendimiento comparado con las ausencias de Mg, K, Mn y P, pués estos elementos fueron favorecidos por la minerilización del estiércol adicionado al cultivo anterior.

Liquefaction tests of toyoura sand measuring change of quasi-elastic deformation properties

Undrained cyclic torsional and triaxial shear tests were perfomed on hollow cylindrical specimens of dense Toyoura sand, which were consolidated isotropically after preparation by airpluviation. At several stress states, quasi-elastic deformation properties were measured by applying very small amplitude cyclic torsional and vertical loads. Some of the results could be explained by considering inhewrent and stress state-induced anisotropy in modeling of elastic deformation characteristics and by correcting for the effects of membrane penetration. Degradation in the values of elastic shear modulus and Young's modulus was observed during liquefaction when compared to those measured during isotropic consolidation.(AU)

Cyclic liquefaction and its evaluation based on the SPT and CPT

Soil liquefaction is a major concern for structures constructed with or on sandy soils. This paper describes the phenomena of soil liquefaction, provides suitable definitions, and provides an update on methods to evaluate cyclic liquefaction using primarily the Standard Penetration. Test and the Cone Penetration Test (CPT). A new method is described to estimate grain characteristics directly from the CPT and to incorporate this into one of the methods for evaluating resistance to cyclic example is also described ffor correcting the results of the CPT in thin layers. A worked example is also provided. This paper is the final submission from the authors to the proceedings of the 1996 NCEER workshop on soil liquefaction; a similar version has been submitted for review to the Canadian Geotechnical Journal. (AU)

Liquefaction resistance based on shear wave velocity

This report reviews the current simplified procedures for evaluating the liquefaction resistance of granular soil deposits using small-strain shear wave velocity. The recomended procedures follows the general format of the SPT-and CPT-based procedures. Liquefaction potential boundaries are esblished by applying a modified relationship between shear wave velocity and cyclic stress ration for constant average cyclic shear strain suggested by Dobry. These new boundaries, which are simply defined mathematically and easy to implement, correctly predict moderate to high liquefaction potencial for more than 95

of the liquefaction case histories. Additional case histories are needed of all types of soil that have and have not liquefied during earthquake, particularty from deeper deposits (deph>8m) and from denser soils (Vs>200m/s) shaken by stronger ground motions (a max>0.4g), to further validate the proposed procedures. (AU)

Model tests on seismic performance of retaining walls

This paper is a preliminary report of ongoing studies for the purpose of developing a rational design method to evaluate stability for several types of conventional retaining walls during an earthquake. Since the seismic behavior of retaining walls is not yet completely understood, a series of tilting and shaking table tests on small scale model are performed. The observed failure pattern and critical condition are compared with the predicted ones that are calculated based on pseudo-static approach. The results show that they are qualitatively consistent. However, the angle of failure planes observed for shaking table tests is steeper than what is predicted. It may suggest that the seismic behavior assumed in the prediction is not fully correct (AU)

Liquefaction of calcareous sands and lateral spreading experienced in Guam as a result of the 1993 Guam earthquake

This paper presents our observations regarding liquefaction-induced ground failures and damage to various facilities.(AU)

Effects of remedial measures against liquefaction at 1993 Kushiro-oki earthquake

During the 1993 Kushiro-Oki earthquake of magnitude 7.8, Kushiro Port being located at 15 km from the epicenter was shaken with a peak horizontal acceleration of 0.47g. Many of the quay walls at the Kushiro Port suffered damage due to liquefaction of backfill sand. However, the quay walls having backfill sand compacted as measures against liquefaction survived the earthquake without damage. In these quay walls, gravel drains were also used as a part of the liquefaction remediation in the vicinity of the walls. Since the contrast in the perfomance of those quay walls are of significance in the engineering practice, the present paper is devoted to report the details including the recorded earthquake motions and the ground conditions.(AU)