Comparison of Radial Consolidation Behavior of Clay under Three Types of Cyclic Loading

Vertical drains and stone columns which have been used in infrastructure construction for highways, ports, coastal regions, etc., provide significant benefits for improving soil characteristics such as reducing the drainage length and accelerating the consolidation process. So the investigation of the radial consolidation is inevitable. Soils may be subjected to cyclic loading such as silos, tanks, etc. This paper presents semi-analytical solutions for radial consolidation and investigates the consolidation behavior under three types of cyclic loading. Consolidation under cyclic loads was calculated using the superimposition rule. Barron (1948) and Olson (1977) have presented theories for calculating radial consolidation under static and ramp load respectively. In this study, by using a set of continuous static loads or a series of infinite ramp loads, with alternatively positive and negative signs, we have extended these theories for rectangular, triangular and trapezoidal cyclic loads. The obtained analytic results demonstrate that the average degree of consolidation at the steady state depends on the integral of the load-time curve for each cycle and it increases with increase of the integral and the results indicate that change in cycle period of time does not effect on the time of getting steady state. Radial and vertical consolidation under rectangular cyclic loading have also compared and the effect of the distance between vertical drains on the time of getting steady state have investigated.