Impact of Plant Root Morphology on Rooted‐Soil Shear Resistance Using Triaxial Testing

Abstract

Mechanical reinforcement by plant roots increases the soil shearing strength. The geometric and distribution characteristics of plant roots affect the soil shearing strength. Current research on the shear strength of rooted-soil is mostly based on direct shear tests with a fixed shear surface and thus cannot reflect the actual failure state of the rooted-soil. In this study, Golden Vicary Privet was used to create a rooted-soil, and a triaxial test method was used for soil mechanical property analysis. The influence of the root geometry (root diameter and individual root length) and distribution characteristics (root density and root distribution angle) on the rooted-soil shearing strength was studied by controlling the root morphology in the specimens. According to the results, both the root geometry and distribution characteristics affect the rooted-soil shearing strength. For a fixed total length of the roots, the longer the individual root length is, the better the soil shearing strength is. In addition, the reinforcement effect of the root system increases as the angle between the root and the potential failure surface increases. The results also show that the root system significantly enhances the soil cohesion while only minimally affecting the internal friction angle. The maximum rooted-soil cohesion is 2.39 times that of the plain soil cohesion, and the maximum internal friction angle of rooted-soil is 1.24 times that of plain soil. This paper provides an approach for the determination of the rooted-soil strength and a rationale for vegetation selection in ecological slope reinforcement applications.

Mechanical Characteristics of Rice Root–Soil Complex in Rice–Wheat Rotation Area

“…However, it had little effect on the internal friction angle. Meng et al [22] drew the same conclusions from their experiments, and in most studies [36][37][38], the conclusions are basically the same.…”

“…Zheng et al [21] carried out shear tests on the rice root-soil complex on a universal material-testing machine with a self-made shear test device. Meng et al [22] performed mechanical analysis of soils containing Golden Vicary Privet roots, and they found that both root geometry and distribution characteristics affected the shear strength of rooted soils. Hou et al [23] studied the use of X-ray-computed tomography (CT) as a non-invasive method to detect root distribution in soil.…”

Vegetation interactions with geotechnical properties and erodibility of salt marsh sediments

“…For example, Patel and Singh (2020) found small increases in shear strength measured by triaxial test conferred to artificial mixtures of clayey and sandy sediments containing glass fibre reinforcement. Meng et al (2020) also observed variability in shear strength related to the rooting geometry of Golden Vicary Privet (Ligustrum spp.) in a controlled planting experiment and found that the root network's effect was largely to enhance the sediment cohesion rather than friction angle.…”

Influence of root distribution patterns on soil dynamic characteristics

“…Generally, the most frequently used root arrangement patterns for the current research are vertical, horizontal, crossed, and mixed arrangements. There is a consensus that crossed and mixed arrangement patterns have a better reinforcement effect than vertical and horizontal distribution patterns 20,21 . On this basis, we chose crossed arrangement and mixed arrangement, which are more closely matched to the actual distribution, for the study comparison.…”

“…First, direct shear tests, as one kind of traditional strength test, have been widely used to investigate the reinforcement effect of different plant roots, and the results showed that the shear strength of root-reinforced soil has improved compared with that of plain soil by root enhancing the soil cohesion 14,15 . Data obtained by subsequent researchers through direct shear tests showed that root geometry [16][17][18][19] (root diameter and root length) and distribution characteristics 20,21 (root density and root distribution angle) had a significant effect on the shear strength of the soil. Second, triaxial compression tests are also commonly conducted to study the properties of root-reinforced soils.…”