Applicability of finger jointing to circular laminated veneer hollow sections for temporary soil nailing

Abstract

This paper investigates the strength properties of circular laminated veneer lumber hollow sections made of beech wood and loaded in tension. These tubular, hollow wooden poles are intended for an innovative geotechnical approach, which utilizes the high tensile strength of beech wood and its limited durability as soil nails for temporary geotechnical slope stabilisation. Due to the standardized design approaches of soil nail walls that prevent a rigid soil body from sliding by using nails as reinforcement elements, primary tension loads will be aligned to the structural elements. Depending on the height of the soil nail wall, nails with a length up to 10 m may be necessary, demanding for high-performance longitudinal section joints due to the natural length limitations of the wood veneer. This paper discusses the applicability of finger jointing to tubular, laminated beech wood veneer poles and presents the results of large-scale tensile tests. Depending on the joint arrangement, the median tensile strength is reduced by 37–43% compared to the unjointed sections of a similar geometry. Thus, finger jointing has been found to be an efficient method of a longitudinal load-carrying connection in combination with a minimized cross section reduction at the joint. However, due to the low sample size of the tests, further improvements are necessary.