Anchorage properties at the interface between soil and roots with branches

Abstract

Roots play an important role in stabilizing and strengthening soil. This article aims to study the mechanical properties of the interface between soil and roots with branches, using the pullout test method in the laboratory. The mechanical properties of the soil–root with branches interface is determined through the pullout-force and root-slippage curve (F–S curve). The results of investigating 24 Pinus tabulaeformis single roots and 55 P. tabulaeformis roots with branches demonstrated three kinds of pullout test failures: breakage failure on branching root, breakage failure on branching node, and pullout failure. The branch angle had a remarkable effect on the failure mode of the roots with branches: the maximum pullout force increased with the sum of the branch diameters and the branch angle. The peak slippage and the initial force had a positive correlation with the sum of the branch diameter. The significance test of correlation between branch angle and the initial force, however, showed they had no correlation. Branch angle and branch root diameter affect the anchorage properties between root system and soil. Therefore, it is important to investigate the anchorage mechanics of the roots with branches to understand the mechanism of root reinforcement and anchorage.

Keywords

Root-soil interface mechanics / Pullout test method / Root branches / Branch angle

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