Determination of soil properties from standard penetration test complemented by torque measurement (SPT-T)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

SPT-T: test procedure and applications

Ranzini (1988) proposed the Standard Penetration Test with torque measurement (SPT-T) and some geotechnical engineers in Brazil have been using it since 1991. This paper presents the state of the art on SPT-T testing, emphasizing what is already established as common knowledge in Brazilian engineering practice, besides a suggestion for test procedure, including equipment and practical aspects. In addition, the study of the shape of the torque versus rotation-degree angle curve obtained by an electric torquemeter used in several SPT-T tests carried out on six experimental research sites in the southeast region of Brazil is discussed here. Four different methods to predict pile capacity based on SPT-T test results are briefly presented and a comparison with load tests carried out on different types of piles, on those six experimental research sites, is presented.

Energy efficiency for standard penetration tests

The need for standardization of the measured blow count number N-spt into a normalized reference energy value is now fully recognized. The present paper extends the existing theoretical approach using the wave propagation theory as framework and introduces an analysis for large displacements enabling the influence of rod length in the measured N-spt values to be quantified. The study is based on both calibration chamber and field tests. Energy measurements are monitored in two different positions: below the anvil and above the sampler. Both experimental and numerical results demonstrate that whereas the energy delivered into the rod stem is expressed as a ratio of the theoretical free-fall energy of the hammer, the effective sampler energy is a function of the hammer height of fall, sampler permanent penetration, and weight of both hammer and rods. Influence of rod length is twofold and produces opposite effects: wave energy losses increase with increasing rod length and in a long rod composition the gain in potential energy from rod weight is significant and may partially compensate measured energy losses. Based on this revised approach, an analytical solution is proposed to calculate the energy delivered to the sampler and efficiency coefficients are suggested to account for energy losses during the energy transference process.

Theoretical and experimental evaluation of the influence of the length of drill rods in the SPT-T test

The influence of soil drill rod length on the N value in the SPT-T test has been studied extensively by Mello (1971), Schmertmann & Palacios (1979), Odebrecht et al. (2002) and Cavalcante (2002). This paper presents an analysis of the Standard Penetration Test supplemented with torque measurement (SPT-T). A theoretical study of the resistance of the rod material to torsion and bending indicated that the shear stress caused by the rod self-weight represents less than 1% of that caused by the torsional moment. An experimental study with electric torquemeters attached to a horizontal rod system, as well as two field tests in the vertical direction, were also carried out to compare and substantiate the results. The purpose of these tests was to analyze changes along the length of the rod in response to successive increments at 1-meter intervals. Torque measurements were taken at each increment of the length to ascertain the accuracy of the theoretical data. The difference between the applied torque and the measured torque at the end of rod system was lower than the minimum scale of mechanical torquemeters used in practice.

Análise da compacidade do solo na área urbana de Bauru/ Estado de São Paulo utilizando Ensaios de Penetração Padronizado e sísmica de refração

This study was done to determine compactness of soil strata in the urban area of Bauru, central São Paulo State using standard penetration test (SPT) and seismic refraction methods. Frequency distribution within boreholes was measured every meter to a depth of 30 meters. The geometric mean of standard penetration test values was computed every meter. A biplot graph showing the relationship of SPT with depth indicates soil stratification. In addition, five sections of seismic refraction values, which also indicate the compactness of soil strata, were obtained. A comparison of the two methods shows significant correlation between the results obtained from each.

The use of CPT to evaluate the effect of helical pile installation in tropical soils

The uplift capacity of helical piles depends on the shear resistance of the soil above the helical plates. During helical pile installation, the soil traversed by the plates are sheared and displaced laterally, and consequently the soil structure is disturbed. Considering this fact, the aim of this paper is presenting the effect of helical piles installation in the soil mass by means of CPT tests carried out close to the soil cylinder above the pile helices. The CPT tests were performed at the CRHEA site from the Sao Carlos School of Engineering, Sao Carlos city, inland of Sao Paulo State, Brazil. In addition, an interpretation of CPT tests data for stratigrafic logging are presented and compared to Standard Penetration Tests (SPT) carried out at this site. This study showed that the CPT sleeve friction fs data were affected by the installation of helical pile in this particular tropical soil site. © 2013 Taylor & Francis Group.

Desenvolvimento de sistema para sísmica up-hole em conjunto com o ensaio SPT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de sistema eletrônico para instrumentar um DPL em ensaio dinâmico de resistência do solo

Pós-graduação em Engenharia Elétrica - FEIS

Go/N ratio in tropical soils from Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison between 100-g glucose tolerance test and two other screening tests for gestational diabetes: combined fasting glucose with risk factors and 50-g glucose tolerance test

CONTEXTO E OBJETIVO: A falta de consenso sobre os protocolos de rastreamento e diagnóstico do diabetes gestacional, associada às dificuldades na realização do teste oral simplificado do diabete gestacional (o teste de tolerância a 100 g de glicose, considerado padrão-ouro) justificam a comparação com alternativas. O objetivo deste trabalho é comparar o teste padrão-ouro a dois testes de rastreamento: associação de glicemia de jejum e fatores de risco (GJ + FR) e o teste oral simplificado de tolerância a 50 g de glicose (TTG 50 g), com o teste de tolerância a 100 g de glicose (TTG 100 g). TIPO DE ESTUDO E LOCAL: Estudo de coorte longitudinal, prospectivo, realizado no Serviço de Ginecologia e Obstetrícia do Hospital Universitário da Universidade Federal de Mato Grosso do Sul. MÉTODOS: 341 gestantes foram submetidas aos três testes. Calcularam-se os índices de sensibilidade (S), especificidade (E), valores preditivos (VPP e VPN), razões de probabilidade (RPP e RPN) e resultados falsos (FP e FN), positivos e negativos da associação GJ + FR e do TTG 50 g em relação ao TTG 100 g. Compararam-se as médias das glicemias de uma hora pós-sobrecarga (1hPS) com 50 e 100 g. Na análise estatística, empregou-se o teste t de Student, com limite de significância de 5%. RESULTADOS: A associação GJ + FR encaminhou mais gestantes (53,9%) para a confirmação diagnóstica que o TTG 50 g (14,4%). Os dois testes foram equivalentes nos índices de S (86,4 e 76,9%), VPN (98,7 e 98,9%), RPN (0,3 e 0,27) e FN (15,4 e 23,1%). As médias das glicemias 1hPS foram semelhantes, 106,8 mg/dl para o TTG 50 g e 107,5 mg/dl para o TTG 100 g. CONCLUSÕES: Os resultados da eficiência diagnóstica associados à simplicidade, praticabilidade e custo referendaram a associação GJ + FR como o mais adequado para o rastreamento. A equivalência das glicemias de 1hPS permitiram a proposição de um novo protocolo de rastreamento e diagnóstico do diabete gestacional, com menores custo e desconforto.

Corn root length density and root diameter as affected by soil compaction and soil water content

Negative effects of soil compaction have been recognized as one of the problems restricting the root system and consequently impairing yields, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in green house studies are necessary for the development of mechanism which alleviates soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. The experiment was conducted to assess the root length density and root diameter of the corn (Zea mays L.) crop as a function of bulk density and water stress, characterized by the soil density (1.2; 1.4, and 1.6 g cm -3), and two levels of the water content, approximately (70 and 90% field capacity). The statistical design adopted was completely randomized design, with four replicates in a factorial pattern of (3 × 2). The PVC tubes were superimposed with an internal diameter of 20 cm with a height of 40 cm (the upper tube 20 cm, compacted and inferior tube 10 cm), the hardpan with different levels of soil compaction were located between 20 and 30 cm of the depth of the pot. Results showed that: the main effects of subsoil mechanical impedance were observed on the top layer indicating that the plants had to penetrate beyond the favorable soil conditions before root growth was affected from 3.16; 2.41 to 1.37 cm cm -3 (P<0.005). There was a significant difference at the hardpan layer for the two levels of water and 90% field capacity reduced the root growth from 0.91 to 0.60 cm cm -3 (P<0.005). The root length density and root diameter were affected by increasing soil bulk density from 1.2 to 1.6 g cm -3 which caused penetration resistance to increase to 1.4 MPa. Soil water content of 70% field capacity furnished better root growth in all the layers studied. The increase in root length density resulted in increased root volume. It can also be concluded that the effect of soil compaction impaired the root diameter mostly at the hardpan layer. Soil temperature had detrimental effect on the root growth mostly with higher bulk densities.

Cotton root volume and root dry matter as function of high soil bulk density and soil water stress

Soil compaction reduces root growth, affecting the yield, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in greenhouses are necessary to develop mechanisms which alleviate soil compaction problems. The selection of three distinct bulk densities based on the Standard Proctor Test is also an important factor to determine which bulk density restricts root penetration. This experiment was conducted to evaluate cotton (Gossypium hirsutum L.) root volume and root dry matter as a function of soil bulk density and water stress. Three levels of soil density (1.2, 1.4, and 1.6 g cm-3), and two levels of water content (70 and 90% of field capacity) were used. A completely randomized design with four replicates in a 3×2 factorial pattern was used. The results showed that mechanical impedance affected root volume positively with soil bulk density of 1.2 and 1.6 g cm-3, enhancing root growth (P>0.0064). Soil water content reduced root growth as root and shoot growth was higher at 70% field capacity than that at 90% field capacity. Shoot growth was not affected by the increase in soil bulk density and this result suggests that soil bulk density is not a good indicator for measuring mechanical impedance in some soils.

Propriedades físicas de um latossolo vermelho manejado com material orgânico e submetido à compactação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The amount of solar energy made available for the production of a sabia (Mimosa caesalpinaefolia Benth.) seed has a determinating effect on its becoming dormant

The amount of solar energy made available for the production of a sabid seed varied as a function of the time of the year, the face of the plant in which, the position in the plant on which and the position in the pod in which it was produced.Variation in solar energy availability as a consequence of the time of the year was a direct consequence of latitude. At 21degrees5'22 S the highest amounts of Global Solar Radiation (GSR) reaching the site where the experiment was conducted took place during the months from November through February. During these months there were no marked differences between any two of the amounts of GSR reaching faces North (N), South (S), West (W) East (E). From February through November (period during which the sabid plants of this study flowered and the resulting seeds matured and were harvested) the total GSR's were the lowest and marked differences were found between faces N and S, with face N receiving much more GSR than face S. During that period, faces W and E received practically the same amount of GSR and it was much less than that received by face N and much more than the one received by face S.The amount of biological energy made available for the development of a seed seemed also to vary according to a dry matter partitioning strategy by the plant -the central third of the plant seemed to be the one receiving the highest amounts of energy, followed either by the upper or the lower third of the plant- it was not very clear which third of the plant immediately followed the central one. The partitioning of biological energy at the pod level also seemed to follow a strategy by which the central seeds would be the ones to receive more, followed by the proximal seeds and these by the distal ones.This availability of energy seemed to have a direct effect on seed size, weight and on the percentage of seeds which showed a degree of dormancy deep enough to prevent their germinating under the conditions of a standard germination test.The implications of these results for the improvement of methods for the overcoming of dormancy of sabia seeds are discussed.