Deep Vibrocompaction at the Natural Frequency of the Soil Response

Abstract

Deep horizontal vibrocompaction is an efficient method of compacting granular soils that has been used and optimized over decades. The state of research indicates that the best possible compaction results are achieved when the vibrator operates at the natural frequency of the vibrator-soil interaction system. However, this approach proved to be unsustainable in practical application. This paper presents a concept for determining the soil response by means of the soil contact force and its phase angle and proposes that an optimized compaction is possible at the natural frequency of the soil response. The considerations are explained using a single-degree-of-freedom (SDOF) model. The admissibility of the approach is demonstrated using measured data as an example. The soil contact force and the phase angle of the soil response are evaluated for selected compaction tests. The evaluation shows that reducing the excitation frequency allows compaction close to the natural frequency of the soil response, requiring less electrical energy, shorter compaction time, and less jetted water. Approaching the natural frequency of the soil response promises to be a valuable criterion for optimizing the deep vibrocompaction process.