Consolidation of soils under cyclic loading effect

Abstract

Cyclic loading may have a relatively short duration for dissipating of pore pressure. The conditions will be undrained during cyclic loading and excess pore pressures will be generated. The generated pore pressures will dissipate after applying cyclic stresses, and the effective stresses will increase to a value of start of cyclic loading again. The volume reduction will occur resulting additional settlements. In this study, pore water pressure, shear strain, consolidation settlements and post-cyclic undrained strength of clays and affecting factors were investigated. For this purpose, a group of samples prepared in the laboratory were tested using cyclic simple shear testing device. The samples were subjected to 5 series of cyclic loading.. Drainage were applied between five cyclic loading stages. At the end of fifth drainage stage, the samples were subjected to undrained static loading. Cyclic tests were performed with stress controlled two way sinusoidal wave loading with different stress levels and number of cycles. Frequency of cyclic loading was constant as 0.1 Hz. As a result of study, it can be concluded that soft clays subjected to undrained cyclic loading and drainage cycles are more resistant to undrained cyclic loadings that can be applied afterwards. The consolidation settlements, pore pressures and shear strains decreases after each stage of cyclic loading. However undrained shear strength increases with increasing pore water pressure induced by cyclic loading.

Özet

Çalışmada, normal konsolide killerin drenajsız tekrarlı yükler altında boşluk suyu basıncı, kayma deformasyonu, konsolidasyon oturmaları, kayma mukavemetleri ile bu davranışları etkileyen faktörler dinamik basit kesme deney sistemi kullanarak deneysel olarak incelenmiştir. Numuneler çamur konsolidasyon aletinde hazırlanmıştır. Deneyler numunelere farklı gerilme oranı ve çevrim sayılarında beş kez sabit genlikli sinüzoidal drenajsız tekrarlı yükleme ve her tekrarlı yük sonrası drenaj uygulayarak yapılmıştır. Beşinci kademe drenajdan sonra numuneler statik olarak kesilmiştir. Çalışma sonunda tekrarlı yükleme ve drenaj uygulanmış killerin daha sonraki tekrarlı yüklere karşı direncinin arttığı. oturma, boşluk suyu basıncı ve kayma deformasyonu her bir tekrarlı yüklemeden sonra azaldığı görülmüştür. Bununla beraber tekrarlı yükleme ve drenaja maruz kalan killerin kayma mukavemeti artmıştır.