Resumo

HERRERA SUAREZ, Miguel et al. Predicting soil resistance during tillage by means of models of passive pressures. Rev Cie Téc Agr [online]. 2015, vol.24, n.3, pp.5-12. ISSN 2071-0054.

For the explanation of the mechanisms that originate the failure of the soil when it is interacted for a farm tool and the prediction of efforts have been developed more than fifty analytic models, reaching the biggest acceptance those that are based on the theory of the passive pressures of the soil. For such a reason, the present work has as objective to determine the accuracy of four models that are based on the universal equation of the soil movement, during the farming of a Rhodic Ferralsol of the occident of Cuba. Was determined experimentally the resistance of the soil during the tillage under controlled conditions in the channel of soils CS-CEMA-25, and were programmed the sequences of calculation of the models Godwin & Spoor, McKyes & Ali,; Grisso et al., in the software Mathcad 15. The main results showed the limitations of these models to predict with accuracy the efforts that arise during the farming in highly cohesive soils, as well as for tools that differ of the geometry for those which originally were developed. It was also demonstrated that a high correlation (r=0.90 to 0.98) exists among the predicted values for these models, evidencing the likeness in the theoretical approaches that base them. On the other hand was observed that the speed of advance of the working tool has very little incidence in the accuracy of the predictions of the investigated models.

Palavras-chave : universal equation of the movement of the soil; angle of friction; logarithmic spiral; method of the wedges.

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