Comparison of field and laboratory models of the load bearing capacity in coffee plantations Compara o de modelos de capacidade de suporte de carga do solo de campo e laboratório em planta es de café

Precompression stress is an important property for assessment of tropical soil structure sustainability and is often determined in laboratory tests. The objective of this study was to compare the load bearing capacity models obtained with controlled moisture in laboratory and those obtained with natural field moistures determined a long one year. The evaluation of soil structural sustainability follows four distinct steps: soil sampling in the field, uniaxial compression test of the samples in the laboratory, determination of precompression stress and estimation of the load bearing capacity models. Laboratory estimates of precompression stress were obtained from moisture controlled in laboratory and from natural moisture determined in a field a long one year. In this process, the soil samples were saturated by capillarity with distilled water in laboratory, and after 48 hours, the samples were air dried to obtain the different moisture contents. Then, the precompression stress was determined for this both conditions. To verify if the load bearing capacity models obtained with controlled moisture in laboratory may represent the load bearing models obtained with natural field moisture, these models were compared using the homogeneity test procedure. It was observed that 75% of field models analyzed were similar to the laboratory models. Thus, due to the similarity on the load-bearing capacity models obtained using natural (field) or controlled (laboratory) moisture contents, the assessment of the soil structure sustainability can be done using both methods. Press o de pré-consolida o é uma importante propriedade na avalia o da sustentabilidade estrutural do solo e é determinada em testes de laboratório. Neste estudo, objetivou-se comparar modelos de capacidade de suporte de carga obtidos com umidade controlada em laboratório e com umidade natural de campo ao longo de um ano. A avalia o da sustentabilidade estrutural do solo ocorreu em quatro etapas: coleta de amostras de solo indeformado, ensaio de compress o uniaxial das amostras em laboratório, estimativa da press o de pré-consolida o e obten o dos modelos de capacidade de suporte de carga. As estimativas da press o de pré-consolida o de laboratório e de campo foram obtidas com umidades controladas em laboratório e com umidade de campo, respectivamente, ao longo de um ano. No laboratório, a satura a das amostras se deu por capilaridade, com água destilada e depois de 48 horas, essas amostras foram secas ao ar para obter diferentes valores de umidade. Em seguida, realizou-se o ensaio de compress o