Determinação de parâmetros geotécnicos (c' e φ) de misturas de solo estabilizado por meio de cisalhamento direto e compressão triaxial

Abstract

There is a predominance of the use of stone materials in the design of pavements at the national level. This is largely due to the consolidation of the techniques used, based on international standards. The use of local soils in paving is an alternative that has already proved e_cient in di_erent studies, allowing a reduction of the transport time in regions without availability of stony material and cost reduction. Tropical soils, common in humid climates such as Brazil, have peculiarities of properties and behavior in relation to other soils. One of the peculiarities of tropical soils is that when compacted they have high bearing capacity and do not exhibit expansion in the presence of water. Lateritic soils, a class of tropical soils, may exhibit very distinct behavior depending on where they are found. This variation of behavior makes it necessary to perform tests to better characterize the di_erent tropical soils found in the country. The tests of direct shear and triaxial compression are the main methods of obtaining the geotechnical parameters, cohesion and friction angle, of shear strength. The objective of this study was to analyze the mechanical behavior of a lateritic soil for paving use through direct shear tests in dry (molding) and saturated conditions, and triaxial compression. The geotechnical parameters were verfied when percentage of lime and ash of rice hulls were added to lateritic soil taken from a mine in the city of Candido Godói - RS, and rupture sheaths were installed. The specimens were cast at the optimum moisture of each mixture and the tests were performed with 28 days of curing in a controlled temperature environment. After obtaining the geotechnical parameters, slope stability analyzes were performed using the Slide software and safety factors were obtained using Bishop, Janbu and Janbu Corrected methods. The results obtained by the direct shear tests in the dry condition, molding humidity, and triaxial compression presented similar results, being possible a greater reliability of the results.The stabilized mixture with lime + ash of rice husk presented the most satisfactory results in comparison with the others, it is believed in the viability of its use. The tests performed in the saturated condition resulted in a decrease in shear strength, with cohesion values and friction angle lower than the tests in the dry condition. It was concluded that there was a gain of shear strength with the stabilization made with lime + rice hull ash. In addition, triaxial compression and direct shear tests proved to be reliable because they generated similar results.