Pedro Domingos Marques Prietto

Variables Controlling Stiffness and Strength of Lime-Stabilized Soils

Lime treatment is an attractive technique for soil improvement in the construction of rail tracks and pavement layers, in slope protection of earth dams, and as a support layer for shallow foundations. However, there are no dosage methodologies based on rational criteria as in the case of soil-cement technology, where the voids/cement ratio is shown to be a key parameter for the estimation of both strength and stiffness. The present study, therefore, was aimed at quantifying the influence of the amount of lime, porosity, and voids/lime ratio on the initial shear modulus (G0) and unconfined compressive strength (qu) of a lime-treated clayey sandy soil. From the results of unconfined compression tests and bender elements measurements, it was shown, for the soil-lime mixtures investigated, that the voids/lime ratio is an appropriate parameter to assess both initial stiffness and unconfined compressive strength. Also, a unique G0/qu versus voids/lime ratio relationship was established linking the soil-lime mi...

Competitive Sorption of Metallic Species under Different pH in a Residual Clayey Soil

AbstractSoil contamination by toxic metals is a major environmental issue, mainly due to inadequate methods of waste disposal and accidental spills. Studies on fate and transport of contaminants he...

INFLUÊNCIA DE CÁDMIO EM SOLUÇÃO MONOESPÉCIE E MULTIESPÉCIE NA SORÇÃO DE METAIS EM LATOSSOLO VERMELHO DISTRÓFICO HÚMICO.

O estudo do transporte de contaminantes inorgânicos no solo e de notavel importância, sobretudo, quando sao considerados os riscos que esses contaminantes podem ocasionar a qualidade das aguas superficiais e subterrâneas. Dentre os contaminantes inorgânicos, estao os metais toxicos, que se apresentam sob diversas formas e exibem comportamentos fisicos e quimicos diferentes. O objetivo do trabalho e avaliar a sorcao de cadmio em solucao monoespecie e multiespecie de metais no solo residual de basalto de Passo Fundo - RS. Amostras de solo foram coletadas do campo experimental de geotecnia da Universidade de Passo Fundo para a moldagem de corpos de prova. Os ensaios foram realizados com a percolacao de 5 mg/L de cadmio em solucao contaminante monoespecie e a percolacao de 5 mg/L dos metais cromo, cadmio, niquel e chumbo, em solucoes multiespecie, estando a solucao multiespecie sob a concentracao total de metais de 20 mg/L. Os corpos de prova foram divididos em cinco camadas e submetidos ao metodo 3050B-EPA para a extracao dos metais. Os resultados possibilitaram encontrar os valores de sorcao presentes em cada camada submetida ao metodo. Cadmio apresentou diferenca no valor de sorcao quando submetido a solucao monoespecie e multiespecie de metais. A maior retencao de cadmio foi observada quando presente em solucao multiespecie de metais. Palavras-chave: solo, metal toxico, retencao ABSTRACT THE INFLUENCE OF CADMIUM IN MULTISPECIE AND MONOSPECIE SOLUTION ON THE SORPTION OF METALS IN HUMIC OXISOIL . The study of the transport of inorganic contaminants in soils has great importance, especially when considering the risk that contaminants may cause in the quality of surface water and groundwater. Among these inorganic contaminants there are toxic metals, which are presented in many different chemical forms that exhibit different physical and chemical behavior. The objective is to evaluate the sorption of cadmium in multispecie and monospecie solutions in the residual basalt soil of Passo Fundo - RS. Soil samples were collected from experimental field of geotechnical engineering at the University of Passo Fundo to molding specimens. The tests were performed with percolation of 5 mg/L of cadmium in monospecie solution and 5 mg/L of toxic metals chromium, cadmium, nickel and lead in multispecie solution, where in multispecie solution the total concentration of metals was 20 mg/L. The specimens were divided into Five layers and subjected to the 3050B-EPA method for extraction of the metals. It was possible to find the values of sorption present in each layer subjected to this method. Cadmium showed differences in sorption value when subjected to monospecie and multispecie solutions. The highest cadmium retention was observed when it presents in multispecie metal solution. Key words : soil, toxic metal, retention

AVALIAÇÃO DO PROCESSO EROSIVO EM ÁREA DEGRADADA POR EMPRÉSTIMO DE SOLO COM A INTRODUÇÃO DE Paspalum notatum

A construcao de empreendimentos de grande porte necessita, na maioria das vezes, do emprestimo de solo de outras regioes. As areas de emprestimo sofrem problemas de degradacao, devido a remocao da cobertura vegetal e extracao do solo, podendo causar fenomenos erosivos. O trabalho avaliou os efeitos da introducao de cobertura vegetal na reducao do processo erosivo em um Nitossolo Haplico de uma area degradada. O estudo aconteceu no canteiro de obras do Aproveitamento Hidreletrico Barra Grande, localizado no municipio de Anita Garibaldi (SC), no rio Pelotas. Foram escolhidas duas areas de estudo. Na primeira (A1) foram realizados dois testes e na segunda (A2) apenas um teste. Cada teste foi realizado em um espaco isolado de 2 x 3 metros e em cada um deles foram adotados dois tratamentos com a introducao da especie Paspalum notatum em 0 % (T1) e 100 % (T2) da area. Em cada parcela, apos as precipitacoes, o material carreado foi enviado para laboratorio para analise granulometrica e quantificacao de massa perdida. A perda de solo para o tratamento 2 (T2) foi 23 vezes menor que o tratamento 1 (T1). O coeficiente de erodibilidade medio foi de 0,23. O estudo permitiu concluir que a introducao da especie Paspalum notatum reduziu consideravelmente o potencial erosivo do solo. Palavras-chave: areas de emprestimo de solo; degradacao; recuperacao ambiental; construcao de barragem ABSTRACT Evaluation of the erosive process in a degraded area by soil extraction with the Paspalum notatum introduction. Large-scale construction usually needs the loan of soil from different deposits. The loan areas suffer problems of degradation due to the removal of vegetable cover and soil extraction that can cause erosive phenomena. This work evaluated the effects of the vegetable cover introduction on the erosive phenomena reduction in a degraded area with Nitosoil. The study was developed in the construction place of the Barra Grande Dam, located in south Brazil at the Pelotas River. Two degraded areas were used in this research. In the first one (A1), two tests were carried out and in the second one (A2) only one test was carried out. Each test was carried out in an isolated space with 2 x 3 m. In each area two treatments had been adopted, one with Paspalum notatum introduction in 100% of the area and the other one without vegetable cover. After each rain period the soil carried by water was collected and taken to the laboratory for grain size analyses and mass quantification. The soil loss in the area with Paspalum notatum cover was 23 times lower than in the area without vegetable cover. The mean erodibility index for the studied soil was 0.23. The study permitted to conclude that the Paspalum notatum introduction reduced considerably the erosive potential in nitosoil. Key words : soil deposit areas, degradation, environmental impact, dam construction