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The analysis of permanent deformations of repeatedly loaded gravels from the Mura region
Gregor Ficko, Bojan Žlender, 2005, original scientific article

Abstract: This contribution presents the results of the analysis of permanent deformations of gravel in the Mura region under repeated loading. The purpose of the analysis is to forecast the development of permanent normalised axial deformations ▫$/epsilon_1^{p*}$▫ regarding the number of loading cycles N and appurtenant stress states during cycling loading. The analysis used the results of tests performed by ZAG Ljubljana and Faculty of Civil Engineering and Geodesy (FGG) of the University of Ljubljana [1]. The analysis considers five types of stonematerials of different quantity of crushed grains in the mixture and of different water contents. Four types of stone materials are mixtures of different portions of crushed grains larger than 2 mm (Dcr = 87.7 %, 58.9 %, 32.6 % in 0 %), and of the water content around w = wopt - 2%. The stone material with portions of crushed grains larger than 2 mm Dcr= 58.9 % is analysed also for water content w = wopt + 0.7 %. The results of the analysis are deformations expressed as a function of the number of loading cycles N, and a spherical component of the repeated loading p and a distortional component of the repeated loading q. The results can be presentedas deformation surfaces in the ▫$/epsilon_1^{p*}$▫ - p - q space for an arbitrary number of cycles N. The relation between the spherical stress component p and the distortional stress component q, at arbitrary values of axial permanent deformations ▫$/epsilon_1^{p*}$▫, gives a failure envelope, and the so called deformation envelopes in the p - q space. The failure envelopes and deformation envelopes are given separately for five types of stone material. The deformation envelopes are low at small values of the axial permanent deformation ▫$/epsilon_1^{p*}$▫ When permanent axial deformations grow, the permanent deformation approaches the failure envelopes. The failure envelopes for individual types of stone material agree with research results performed by [1]. The analysis of permanent deformations also shows their dependence on the portion of crushed material Dcr in the mixture of crushed and uncrushed stone material. The deformation envelope for uncrushed stone material is situated in the lowest position, regarding the portion of crushed material in the mixture. With an increased portion of crushed material in the mixture of crushed and uncrushed stone material, the deformation envelope is also higher, similarly to the lawfulness of failure envelopes. The relation of failure and deformation envelopes is mathematically established as a function of the portion of crushed grains larger than 2 mm. The comparison of stone material results for different water contents shows that a minimal increase of water content above the optimal one essentially increases deformation.
Keywords: building materials, Mura river gravel, cyclic triaxial tests, granular base material, permanent deformation, normalized axial permanent deformation
Published: 01.06.2012; Views: 990; Downloads: 24
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