Development of new tables of transition factors from the results of compression tests to the plate-bearing modulus

Abstract

The article is devoted to the issue of developing new tables of transition factors relating the results of compression and plate-bearing tests. As is known, the normative value of the modulus of deformation is directly determined from the most reliable plate-bearing tests. However, they are quite laborious and expensive. In contrast to plate bearing tests, compression tests are much cheaper, but they give underestimated values of the deformation modulus. In this connection, a table of transition coefficients from a compression module to a plate-bearing deformation modulus was developed (Agishev – Ignatova table). The article shows that the initial stress ranges selected for the determination of the compression and platebearing deformation modulus differ significantly. The compression module, as well as the odometric modulus of deformation in the latest version of the table, was determined in a fixed pressure range, and the plate-bearing test curve for the linear section, the starting point of which is an alternating natural effective stress. To eliminate this contradiction, when developing new tables, instead of a compression modulus, a tangential odometric modulus of deformation was used, determined for the corresponding value of the natural effective stress. The algorithm for determining new transition coefficients is described in detail. In the new tables, in addition to the porosity coefficient, the soil flow rate is also taken into account. The effect of consistency on the definition of the plate-bearing modulus and the absence of such an effect on the results of compression tests are noted. Anomalous behavior of clay of solid consistency is shown during compression tests. In addition to the tables of transition coefficients, a table of linear equations is provided for a direct transition from the results of compression tests to a plate-bearing deformation modulus. New tables are proposed to be used to determine the standard value of the modulus of soil deformation at the stage of preliminary calculations for the foundations of buildings and structures of the II and III geotechnical categories.