| Summary: | When considering the influence of suction on foundations projects or on construction materials of engineering works, a more realistic soil behavior results, because it is common to find it in nature in its partially saturated state. There is still the financial benefit because in some cases the project is less costly. The present work presents an experimental and numerical study in an unsaturated soil. The experimental studies are composed of laboratory and field tests, and the numerical analyzes were performed using the UNSTRUCT finite element program (Miranda, 1988 and Silva Filho, 1998), which performs stress and strain analyzes under state conditions and considers the influence of suction on soil rigidity. The soil used for research, a poorly graded, non-plastic sand, originates from the geotechnical experimental field of the Federal University of Ceará, in Fortaleza / CE. The experimental studies began with laboratory tests, more precisely with characterization tests, filter paper assay and double edometric assay. The filter paper test was performed to determine the retention curve. The double edometric test was performed to determine the vertical versus vertical strain curve using a sample saturated by previous flood and another in in situ humidity conditions. For the "versus" stress curve, two field trials were carried out: plate loading tests with natural soil, and another with flooded soil. The two tests were done with the application of rapid loading. The experimental results obtained showed a small suction variation, from 0 to 58 kPa, estimated from the retention curve. The results of the plate loading test and the double edometric test showed higher stiffness and, consequently, lower soil settling, for a lower moisture value. The numerical analysis showed the influence of the stress increase on the deformation of the soil mass when the water level and, consequently, the level of suction were changed. In addition, the use of the UNSTRUCT program (Miranda, 1988 and Silva Filho, 1998) showed results consistent with the suction distribution in the massif being characterized as a quick and simple alternative for estimation of foundation settlements based on soil profiles subject to influence of the suction.
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