CaracterizaÃÃo geotÃcnica de um solo de calcÃrio da Encosta Continental/PE-18, Paulista-PE, com Ãnfase na resistÃncia ao cisalhamento




The main objective of this dissertation is the study of the geotechnical characteristics, of the layer of calcareous silty clay involved in the landslides that occurred in an area situated in highway BR 101 North, PE 18, in the industrial district of Paulista, with emphasis in its shear strength. A slope with instability problems between highway PE- 18 and the old stove factory âContinental stovesâ. This slope was subjected to several episodes of movements since two almost simultaneous interventions in the geometry of the slope were made: one, the placement of an embankment in its top for the construction of highway PE-18, and the other a cut at the base for the construction of the factory, in the beginning of the seventies. Different solutions, usually retaining structures, were executed trying to stabilize it, but without success. Most of the sliding surface was on a single layer of a yellowish soil, and the cause of the sliding could be either through high pore pressures or a low friction angle. Since this soil was little studied, mainly with respect to its shearing strength properties, a thorough study of its geotechnical parameters was decided upon. The geotechnical characterization of this material was performed, and, compressibility, hydraulic conductivity, mineralogical and soil chemistry tests were also included. The emphasis of the study rests on the soilâs shear strength parameters, chiefly its residual strength, considering that this slope has a history of reactivated slides along a preferred slip plane. Undisturbed block samples of this soil were collected in the area of the failed slope, and also at another close location, in the same geological layer, at the other side of the hill where the slides took place, considering that in this location the soil should be in its intact state, without deformations. The test results showed similar materials. The strength tests included direct shear and direct shear with multiple reversals, and also ring shear tests (Bromhead apparatus) and direct shear tests on a polished surface. The residual friction angles obtained were high, with values close to the peak friction angles. These values are situated in the range of 31,6Â to 32,6Â for the peak condition and 24,6Â a 29Â for the residual condition. These results are in agreement with the mineralogy of this soil, that show in its composition a high percentage (of the order the 70%) of calcite. The influence of mineralogy and the constituent pore fluid and the influence the rates of displacement of the shear tests was also studied. At last, the geotechnical characteristics of this calcareous soil were compared with those of other similar materials found in the literature


mecÃnica de solos (engenharia civil) â teses cisalhamento âteses solo de calcÃrio â teses engenharia civil

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