Name: ANITA CURITIBA CHRYSTELLO
Type: MSc dissertation
Publication date: 29/07/2017
Advisor:
Name |
Role |
|---|---|
| KÁTIA VANESSA BICALHO | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| KÁTIA VANESSA BICALHO | Advisor * |
Summary: 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.
