Avaliação de curvas de calibração do método do papel filtro tipo Whatman nº42 utilizadas para estimar sucção matricial em solos não saturados

• Autor(a) principal: Chrystello, Anita Curitiba
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/9494
• topic: Unsaturated soils; Soil suction measuring; Filter paper method; Calibration of filter paper; Método do papel filtro; Medição de sucção; Solos não saturados; Calibração do papel filtro; Engenharia Civil; Mecânica do solo; Sucção - Medição; Calibração; 624

The filter paper method is a simple and economical method for estimating suction in unsaturated soils. The filter paper method estimates the suction, s, in soil indirectly by measuring the gravimetric water content of filter paper, wf, at hydraulic equilibrium with the soil using a predetermined calibration curve. A number of calibration functions for the Whatman No. 42 (W42) filter paper have been published in the literature. Varieties of techniques (pressure plate, pressure membrane and vacuum desiccator) are used to apply suction values to obtain the calibration curve (wetting paths) to W42 filter paper. Most of the calibrations involve a bilinear function (two different equations) with an inflection point occurring at 60 kPa < s < 100 kPa (i.e., 40% < wf < 50%). An approach for defining a continuous calibration function with a smooth transition between the high and low suctions based on a regression analysis of experimental data from various previously published calibrations obtained for filter paper Whatman No. 42 (W42) is presented and discussed. This paper presents a statistical analysis of the evaluated calibrations (bilinear and exponential equations) have been published in the literature for the W42 filter paper for soil suctions of unsaturated soils inferred from the filter paper method . New exponential calibrations are defined herein to fitting experimental data used to determine the bilinear equations proposed by ASTM D5298-10 and Leong et al. (2002).Finally, an experimental study was also conducted to compare the suctions estimated by the contact filter paper method test using different calibration with suctions measured by other laboratory techniques for two different soils. The results show that the exponential calibration suggested herein has considerable potential to be used for soil suctions of unsaturated soils inferred from the filter paper method. However, more measured data are required with different soil textures and differences suction range to evaluate of the suggested exponential calibration.