Mechanisms of root-soil reinforcement in bio-embankments of sloping farmland in the purple hilly area, China

Jin, Huifang; Shi, Dongmei; Zeng, Xiao-Ying; Wang, San-shu; Duan, Teng; Lou, Yibao

doi:10.1007/s11629-019-5476-x

Cited by 17 publications

(7 citation statements)

References 59 publications

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“…In this study, the cohesion of rooted soil was greater than that of plain soil. This shows that root systems contribute to increases in soil cohesion (Jin et al, 2019; Liu et al, 2021). This additional cohesion is mainly caused by the mechanical resistance of the roots and the interfacial friction between the root system and soil particles (Zhou & Qi, 2018).…”

Section: Discussionmentioning

confidence: 98%

Impact of Dicranopteris linearis roots on the shear strength of different soil layers in collapsing wall of Benggang

Zhou

Shuai

Chen

et al. 2022

European J Soil Science

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‘Benggang’ is a local term for a widespread type of severgully erosion with steep collapsing walls in granitic, low, hilly areas of southern China, and its development and expansion are closely related to the shear strength of the collapsing wall. Plant roots play an important role in improving soil shear strength. However, the shear strength of root‐soil complexes in different layers of collapsing walls remains obscure. We selected Dicranopteris linearis fern roots and adopted the direct shear method to evaluate the effect of root weight density (RWD) (0–1.25 g 100 cm−3) on the shear properties of the lateritic, sandy and detritus layers. The results showed that roots could enhance soil shear strength, and the maximum increase in the lateritic layer was 11.53%, higher than that in the sandy (5.84%) and detritus layers (3.17%). As the root content increased, the cohesion of the sandy and detritus layers increased and then decreased, and their maximum increase in cohesion and the fitting optimal RWD were lower than those of the lateritic layer. The internal friction angle was not affected by roots. When the root content was constant, the shear strength and cohesion of the lateritic layer were significantly higher than those of the sandy and detritus layers, while their internal friction angle was significantly lower than that of the latter two layers. The average increment of soil cohesion calculated by the Wu‐Waldron model (WWM) was 10.52 kPa, which was 0.30, 3.75 and 19.38 times the measured average values of the lateritic, sandy and detritus layers, respectively. The correction coefficient k′ was 0.02–1.18, and the truek'¯$$ \overline{k\hbox{'}} $$ in the lateritic layer was the highest (0.82), followed by that in the sandy and detritus layers. By combining the modified WWM with Coulomb's formula, new shear strength equations for root‐soil complexes of D. linearis were established. The predicted shear strength compared well with the measured shear strength (R2 > 0.90, NSE >0.90). Overall, the roots only had a significant reinforcement effect on the lateritic layer, and they could still not change the mechanical properties of the collapsing wall, which were more stable in the upper layers and weaker in the bottom. Therefore, other measures should be taken in the bottom layers to improve the stability of Benggangs. Highlights Effect of D. linearis roots on the shear strength of collapsing walls in Benggang was studied. Roots could improve collapsing‐wall soil shear strength, mainly reflected in the cohesion. The roots enhancement effect in lateritic layer was better than that of sandy and detritus layers. New shear strength equations of root‐soil complexes were established based on the Wu‐Waldron model.

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Section: Discussionmentioning

confidence: 98%

Impact of Dicranopteris linearis roots on the shear strength of different soil layers in collapsing wall of Benggang

Zhou

Shuai

Chen

et al. 2022

European J Soil Science

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“…With an increase in root diameter, the tensile cross-sectional area increased, and the lignin and cellulose content of root fibers increased, as did the maximum tensile stress of root fibers. However, the growth rate of the maximum tensile stress was less than that of the diameter [40][41][42]. According to formula (1), when the growth rate of the root fiber tensile stress is less than that of the diameter, the tensile strength of the fibers decreases (Figure 4).…”

Section: Influence Of Carex Root Fiber Diameter On Tensilementioning

confidence: 99%

Experimental Study on Shear Resistance of Carex‐Root‐Fibered Soil

Wang

Zhao

Sun

2021

Advances in Civil Engineering

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Carex shows strong vitality, adaptability, and performance with regard to soil consolidation and slope protection but is often disregarded as a weed. This study proposes to turn this so-called weed into treasure, using its characteristics to protect the slope. We studied the interaction between the carex roots and soil and compared it to other types of grass. To understand the interaction between the carex roots and soil, this study investigated the tensile properties of the carex root fibers. The effects of fiber content, humidity, distribution, and soil moisture content on the relationship between the shear strength and vertical pressure of the soil were analyzed using a direct shear test. Furthermore, the cohesion and internal friction angle were used to evaluate the shear strength of the root-fibered soil based on Mohr–Coulomb’s law. The results showed that the smaller the diameter, the shorter the length, and the greater the quantity and the lower the humidity of the root fibers, the higher the tensile strength of root fibers. In addition, the soil strength could be improved by the joint action of the roots and the soil. With an increase in the root fiber content and humidity, the soil moisture content decreased, whereas the shear strength of the carex-root-fibered soil increased. Here, four kinds of root fiber distributions, namely, “glyph,” “herringbone,” “eccentric,” and “vertical,” were chosen to study the shear strength of the root-fibered soil. The results showed that “glyph” root fiber distribution had the highest shear strength, while the shear strength decreased for the others.

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“…The shear strength was measured under three different vertical loads as the peak point on the stressdisplacement curve or, if no peak point was evident, as the stress value corresponding to a displacement of 4 mm. To apply Coulomb's equation [31], the cohesion and internal friction angle of each mix τ r c ϕ containing y ash were also identi ed. Each test was performed on at least ve samples, the maximum and minimum values were removed, and the average of the middle three values was taken.…”

Section: Substrate Mechanical Propertiesmentioning

confidence: 99%

Functionality Optimizing Study On Coal-bearing Soil Ecological Substrates

Huang

Zheng

2022

Preprint

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Ecological restoration is of profound significance for protecting the ecology and engineering safety of coal-bearing soil (CBS) areas. However, the formulations of CBS ecological substrates have rarely been explored. The objective of this study was therefore to evaluate the effects of the CBS:soil ratio (1000:0 g, 750:250 g, 500:500 g, 250:750 g), fly ash content (0, 50 g·kg− 1, 100 g·kg− 1, 150 g·kg− 1), maize straw content (0, 20 g·kg− 1, 40 g·kg− 1, 60 g·kg− 1), and expanded polystyrene (EPS) content (0, 3 g·kg− 1,6 g·kg− 1, 9 g·kg− 1) in an orthogonal design to optimize an ecological substrate according to various physicochemical, nutrient content, mechanical, and vegetation parameters. The results indicated that the CBS:soil ratio had significant effects on the nutrient content and vegetation growth parameters; fly ash dramatically improved the mechanical parameters (shear strength, cohesion, and internal friction angle); maize straw significantly affected the physical parameters and improved the substrate nutrient content; and EPS was the most beneficial to the vegetation germination ratio. A CBS:soil ratio of 1:1 (500:500 g), fly ash content of 100 g·kg− 1, maize straw content of 50 g·kg− 1, and EPS content of 6 g·kg− 1 were determined to produce the optimal mix for the ecological restoration of CBS. The conclusions of this research provide theoretical and practical guidance for the ecological restoration and stabilization protection of CBS slopes.

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Mechanisms of root-soil reinforcement in bio-embankments of sloping farmland in the purple hilly area, China

Cited by 17 publications

References 59 publications

Impact of Dicranopteris linearis roots on the shear strength of different soil layers in collapsing wall of Benggang

Impact of Dicranopteris linearis roots on the shear strength of different soil layers in collapsing wall of Benggang

Experimental Study on Shear Resistance of Carex‐Root‐Fibered Soil

Functionality Optimizing Study On Coal-bearing Soil Ecological Substrates

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