Assessment of clay soils strengthening under triaxial cyclic loading

Abstract

One of the main issues in the design of foundations is the correct forecast of the development of long-term deformations (settlement) of the foundations. Among the main factors affecting settlement, one can single out the neglect of changes in the rheological parameters of the soil in time and the neglect of the loading regime, as well as the processes of soil hardening in time. The work presents the results of a study of the behaviour of samples of clayey soil with a disturbed structure under conditions of triaxial cyclic loading, taking into account the strengthening effect. The relevance of the problem of studying the hardening process is associated with the assessment of the deformability and strength of clays with rheological properties. The tests were carried out in a pneumatic stabilimeter with an artificial soil created of paste. After preparing the samples, they were placed in a sealed container until the start of the test for a period of 1 to 5 days. To establish the ultimate strength of the soil, single static loads were carried out at a given value of the uniform pressure. The main control characteristics during the tests were the maximum and minimum values of the cycle voltages. If the sample did not fail during cyclic loading, it was destroyed by a stepped increase in the static load. The dependences of the change in the strength of a clay soil sample during the holding time before the start of the test were obtained at various values of all-round compression and the amplitude of the cycle. The strength of the soil with a change in the holding time increased up to 1.27 times.