Analytical modeling of the stick-slip motion of an oscillation drum

Abstract

In this paper, a lumped parameter model of the interacting oscillation roller-subsurface system is proposed. The main aim of the model is to predict the response acceleration of the roller drum during nearsurface compaction of non-cohesive soils. The compaction process of the soil itself is not captured, but different degrees of compaction are considered by varying the soil stiffness. The roller is represented by the oscillation drum and its viscoelastic connection to the roller frame. In the chosen modeling strategy, the curvature of the soil surface below the drum is prescribed. In this way, also the vertical drum acceleration can be computed. The discrete subsoil model consists of a vertical and a horizontal Kelvin-Voigt element. Contact between drum and soil surface is described by means of dry friction according to Coulomb's law. As such, the stick-slip motion of the drum can be simulated. In the stick phase, pure rolling between drum and soil surface is assumed. The highly nonlinear equations of motion of this three degrees-of-freedom model are derived separately for the stick and the slip phase of the motion. Selective numerical studies show that this model captures the fundamental response characteristics of the dynamic drum-subsoil interacting system observed in the field. 1 Introduction A roller, also often referred to as roller-compactor, is a heavy equipment used for near-surface compaction of soil and asphalt layers in the construction of various civil structures such as roads, airfields, dams, and track foundations. A static roller uses only its weight to compact the layer, whereas a dynamic roller enhances the efficiency of subsurface compaction through dynamic excitation of the drum. Depending on the drum excitation, two basic types of dynamic rollers do exist, i.e., vibratory rollers and oscillation rollers. They differ in design, mode of operation, and how the medium to be compacted is loaded. In a vibrating drum, a single unbalance mass, which is attached concentrically to the drum axis, generates a rapidly alternating upwarddownward motion of the drum. The subgrade is compacted by the dynamic pressure applied by the drum. An oscillation drum is equipped with two offset eccentric masses, which rotate synchronously in the same direction. The resulting alternating high-frequency forward-backward motion of the drum, superposed with the translational roller motion, imposes dynamic shear forces that increase the subsurface density. Continuous Compaction Control (CCC) ([1,11]) has become the standard technology for controlling subsurface compaction by vibratory rollers. This control technique is based on the dynamic response of the interacting drum-subsurface system recorded during the roller pass, and thus, allows an instant continuous assessment of the degree of compaction. For oscillation rollers, however, no mature CCC system has been

Simulation of the stick‐slip motion of an oscillatory roller

“…In particular, the frequency content of the drum accelerations x M andz M is set in contrast (see Fig. The computed drum responses of the 3DOF LPM and the FE model are in good agreement if the contact length resulting from the FE simulations is used when calculating the parameters of the spring-dashpot damper elements, which describe the elastic soil halfspace according to [4] ("LPM-1"). The computed drum responses of the 3DOF LPM and the FE model are in good agreement if the contact length resulting from the FE simulations is used when calculating the parameters of the spring-dashpot damper elements, which describe the elastic soil halfspace according to [4] ("LPM-1").…”

“…A curved dent, which approximates the settlement trough of the 2 of 2 Section 5: Nonlinear oscillations subsoil below the drum, is prescribed, supported by a discrete spring-damper soil model (spring coefficients k sh and k sv , and damping parameters c sh and c sv ) representing the soil halfspace [3]. 2) calibrated to the actual soil surface shape [4]. 2) calibrated to the actual soil surface shape [4].…”

“…M u sin (νt) and the constant driving torque M M d imposed by the roller engine (for details see [4]). Moment M M d forces the drum to oscillate on the slope of its settlement trough in driving direction.…”

“…[2]). A recently proposed more advanced mechanical 3DOF LPM [4] shown in Fig. A recently proposed more advanced mechanical 3DOF LPM [4] shown in Fig.…”

“…1: Oscillating roller with smooth drum (schematic) [4]. 1: Oscillating roller with smooth drum (schematic) [4].…”