Penetration Properties of Ground Lugs of Portable Supports for Timber Rafting

Abstract

Portable fillable supports for fastening timber rafting structures meet the requirements for devices that facilitate the implementation of a concept for the efficient and environmentally friendly transportation of timber along small and medium-sized rivers. Reliable operation of such supports is assumed when the vertical elements of the ground lugs are completely immersed into soil. In order to achieve this level of immersion, we need information about the effort required in this particular case. The research aims to ensure the reliable operation of portable fillable supports with ground lugs. We have used the theoretical and experimental research method. The results include analytical dependencies for the penetration forces of the ground lugs’ sections. These factors allowed us to identify the variables that determine the output values, as well as the nature and extent of the factors’ influence. Performing calculations based on these dependencies does not provide reliable results, since the ground stresses occurring beneath the lower edges and on the lateral surfaces of the ground lugs at the considered depths are unknown. We have found that the force required to drive the ground lug section into the soil depends on the same soil parameters as the number of blows required by the dynamic densimeter to drive its tip to the required depth and the specific penetration resistance measured by the penetrometer. Laboratory experiments, based on prior theoretical studies, confirmed that there is a clear relationship between the three parameters mentioned. In view of this relationship, experimental studies were carried out under field conditions. Approximate dependencies of the forces required to drive in the recommended sections of ground lugs were obtained based on the average number of blows from a dynamic densimeter and the specific penetration resistance. The values of the considered forces for a number of soil types are given, based on the maximum values recorded during experiments. The approximate dependencies and force values provided here will enable the most effective resolution of issues related to ensuring the penetration of ground lugs into soil and will contribute to the reliable operation of the studied supports.