scholarly journals Impact of Plant Root Morphology on Rooted-Soil Shear Resistance Using Triaxial Testing

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Suyun Meng ◽  
Guoqing Zhao ◽  
Yuyou Yang
Keyword(s):  
Internal Friction ◽  
Root System ◽  
Root Morphology ◽  
Root Length ◽  
Friction Angle ◽  
Plant Roots ◽  
Distribution Characteristics ◽  
Soil Cohesion ◽  
Shearing Strength ◽  
Individual Root

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.

scholarly journals Inverse distance weighting interpolated soil properties and their related landslide occurrences

2018 ◽  
Vol 195 ◽  
pp. 03013 ◽  
Author(s):  
Purwanto B. Santoso ◽  
Yanto ◽  
Arwan Apriyono ◽  
Rani Suryani
Keyword(s):  
Internal Friction ◽  
Slope Stability ◽  
Soil Properties ◽  
Hard Rock ◽  
Friction Angle ◽  
Inverse Distance Weighting ◽  
Central Java ◽  
Soil Cohesion ◽  
Distance Weighting ◽  
Inverse Distance

The causes of landslides can be categorized into three factors: climate, topographic, and soil properties. In many cases, thematic maps of landslide hazards do not involve slope stability analyses to predict the region of potential landslide risks. Slope stability calculation is required to determine the safety factor of a slope. The calculation of slope stability requires the soil properties, such as soil cohesion, the internal friction angle and the depth of hard-rock. The soil properties obtained from the field and laboratory investigation from the western part of Central Java were interpolated using Inverse Distance Weighting (IDW) to estimate the unknown soil properties in the gridded area. In this research, the IDW optimum parameter was determined by validation toward the percent bias. It was found that the IDW interpolation using higher weighting factor corresponds with a higher percent bias in case of the depth of hard-rock and soil cohesion, while the opposite was found for the internal friction angle. Validation to landslide incidents in western parts of Central Java shows that the majority of landslide incidents occur at depths of hard rock of 6 m-8 m, at soil cohesions of 0.0 kg/cm2-0.2 kg/cm2, and at internal friction angles of 30°-40°.

Experimental Study of the Shear Strength of Cobalt-Rich Crusts

2013 ◽  
Vol 419 ◽  
pp. 576-580 ◽  
Author(s):  
Hong Yun Wu ◽  
Zheng Chen
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Internal Friction ◽  
Empirical Formula ◽  
Laboratory Testing ◽  
Friction Angle ◽  
Strength Test ◽  
Strength Parameter ◽  
Shearing Strength

The shear strength parameter of cobalt-rich crusts can be used to design cobalt-rich crusts mining head. The shearing test of cobalt-rich crusts sample was done with different angle shearing testing apparatus.Firstly, the cobalt-rich crusts sample with the size of 50mmx50mmx50mm cube was clamped in the variable angle plate.Secondly, the sample ware loaded till to be damaged. Lastly,the damaged load were recorded at the degree of 50, 60 and 70 to establish their shearing strength and normal stress empirical formula.According to the testing result, its cohesion and internal friction angle parameters are respectively 0.275MPa and 54.43 degree. Restricted by the number of samples and limited by laboratory testing,in-situ shearing strength test should be carried out to improve the proposed empirical formula.

Study on the Effect of Water Content on Shearing Strength Parameters of Unsaturated Loess

2014 ◽  
Vol 638-640 ◽  
pp. 585-588 ◽  
Author(s):  
Si Zhong Qian
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Micro Particles ◽  
Shearing Strength ◽  
Unsaturated Loess

This paper experiments on typical Malan loess, performs consolidated quick direct shear tests under different water contents by conventional direct shear apparatus, then analyzes the effects of water content on shearing strength parameters, namely cohesion and internal friction angle. The results show that cohesion decreases linearly as the water content increasing, and the relation could be obtained by data fitting. However, internal friction angle keeps basically stable with the increase of water content. Finally, based on the force analysis for micro particles, the changing rules of cohesion and internal friction angle with water content were deeply explained.

Raising the Efficiency of Seohen's Model to Predict Soil Resistance Faced by Chisel Plow

2021 ◽  
pp. 257-273
Author(s):  
Adil Abd Elsamia Meselhy
Keyword(s):  
Mechanical Properties ◽  
Internal Friction ◽  
Broad Bean ◽  
Friction Angle ◽  
Plant Roots ◽  
Soil Resistance ◽  
Forward Speed ◽  
Wheat Roots ◽  
Mean Diameter ◽  
Chisel Plow

This research was carried out to study the effect of crop factor, which is represented in some plant roots of crops residues (broad bean and wheat) on soil mechanical properties (cohesion strength, C, and internal friction angle, Φ), and thus, the effect of these roots on the power requirements of chisel plow to face the soil resistance was studied. Soil mechanical properties and power requirements of chisel plow (7 blades) were measured in the field directly at various soil depths of (0.05, 0.1, 0.15, and 0.2 m) with and without roots at constant tractor forward speed of about 4 km/h. Moisture content of the soil, broad bean roots, and wheat roots were 21%, 16%, and 14%, respectively, The results showed that the effect of roots of previous crops residues had a significant effect on the soil mechanical properties and power requirements for chisel plow when using the crop factor, which is represented in characteristic of crop residual roots in terms of root mean diameter.

Evolutionary divergences in root system morphology, allocation, and nitrogen uptake in species from high- versus low-fertility soils

2016 ◽  
Vol 43 (2) ◽  
pp. 129 ◽  
Author(s):  
Alan W. Bowsher ◽  
Benjamin J. Miller ◽  
Lisa A. Donovan
Keyword(s):  
Root System ◽  
Root Morphology ◽  
Root Length ◽  
N Uptake ◽  
High Capacity ◽  
Specific Root Length ◽  
Mineral Resources ◽  
Low Fertility ◽  
15N Tracer ◽  
Adaptive Differentiation

Root morphology and nutrient uptake processes are essential for acquisition of mineral resources from soil. However, our understanding of how root form and function have diverged across environments is limited. In this study, we addressed hypotheses of adaptive differentiation using three pairs of Helianthus species chosen as phylogenetically-independent contrasts with respect to native soil nutrients. Under controlled environmental conditions, root morphology, allocation, and nitrogen (N) uptake (using a 15N tracer) were assessed for seedlings under both high and low N treatments. Species native to low nutrient soils (LNS) had lower total root length than those native to high nutrient soils (HNS), reflecting the slower growth rates of species from less fertile environments. Contrary to expectations, species did not consistently differ in specific root length, root tissue density, or root system plasticity, and species native to LNS had lower root : total mass ratio and higher 15N uptake rates than species native to HNS. Overall, these evolutionary divergences provide support for adaptive differentiation among species, with repeated evolution of slow-growing root systems suited for low resource availability in LNS. However, species native to LNS maintain a high capacity for N uptake, potentially as a means of maximising nutrient acquisition from transient pulses.

scholarly journals Estimation of Soil Shear Strength Indicators Using Soil Physical Properties of Paddy Soils in the Plastic State

2021 ◽  
Vol 11 (12) ◽  
pp. 5609
Author(s):  
Qianjing Jiang ◽  
Ming Cao ◽  
Yongwei Wang ◽  
Jun Wang ◽  
Zhuoliang He
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Clay Content ◽  
Friction Angle ◽  
Soil Samples ◽  
Internal Friction Angle ◽  
Paddy Soils ◽  
Interactive Effects ◽  
Soil Cohesion ◽  
Soil Shear Strength

Saturated soil shear strength is a primary factor that reflects the driving resistance of agricultural machinery in paddy soils. The determination of soil shear strength indicators, such as cohesion and internal frictional angle, is crucial to improve the walking efficiency of agricultural machinery in paddy soils. However, the measurement of these indicators is often costly and time-consuming. Soil moisture content, density, and clay content are crucial factors that affect the cohesion and internal friction angle, while very limited studies have been performed to assess the interactive effects of the three factors on soil shear characteristics, especially on paddy soils. In this study, eight soil samples were taken from eight paddy fields in Southeastern China, and the central composition rotatable design was used to classify the soil samples into five levels based on different clay content (X1), moisture content (X2), and density (X3). The direct shear tests were carried out indoors on the remolded paddy soil using a self-made shear characteristic measuring device. Then, both individual and interactive effects of X1, X2, and X3 on soil cohesion and internal friction angles on paddy soils were systematically investigated and analyzed using the regression analysis method in the data processing software Design-Expert. Our results indicated that the effects of the three environmental factors on soil cohesion were in the order of X1 > X2 > X3, while the order was X2 > X3 > X1 for the impact on internal friction angle. The interactive effects were in the order of X1X2 > X1X3 > X2X3 for cohesion and X1X2 > X2X3 > X1X3 for internal friction angle. Two prediction models were successfully established to quantify the soil cohesion and internal friction angle as affected by soil physical properties, and the coefficient of determination (R2) was 0.91 and 0.89 for the two equations, respectively. The model validations using new soil samples suggested that the models were capable of predicting the shear characteristic parameters under different physical parameters effectively, with errors between predicted and measured soil shear strength indicators within 15% and relative root mean square error less than 11%.

scholarly journals Influence of vetiver root on strength of expansive soil-experimental study

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244818
Author(s):  
Gui-yao Wang ◽  
Yong-gang Huang ◽  
Run-fa Li ◽  
Jing-mei Chang ◽  
Jin-liang Fu
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Root System ◽  
Shear Test ◽  
Expansive Soil ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Strength Parameter ◽  
Shear Strength Parameters ◽  
Strength Parameters

Grassroots have received more attention than the traditional method as soil reinforcement materials, especially the use of vetiver and other vegetation protection methods to treat expansive soil slope, have been tried and applied. To study the influence of grassroots on the strength properties of expansive soil, the laws of vetiver root growth over time and its vertical distribution of root content(δ) were firstly investigated by the experiment of planting vetiver. Then different δ and depth of planted soil were obtained. Simultaneously different δ and water content(ω) of grafted soil were made. With the direct shear test, the shear strength parameters of root-soil with different δ were analyzed. The shear test on root-soil composites with different δ was carried out to compare the strength characteristics of planted and grafted soil. The results showed that the δ of vetiver decreased with the increase of depth, and the δ of each layer increased with the growth period. The δ of 180d was 70.5% higher than that of 90d. The cohesion(c) of root-soil can be increased by more than 97%, and internal friction angle(φ) can be increased by more than 15.4% after 180 days. The c of 90 d vetiver root system can be increased by more than 18%, and the φ can be increased by more than 1.5%. At each depth, the c and φ of composite soil increases with the increase of δ, and the increment of cohesion (Δc) and the increment of internal friction angle (Δφ) increase with the increment of δ. But the increase in the ω will weaken the shear strength parameters of root-soil. Under the condition of the planted root system and grafted root system, the influence degree of δ on strength parameter of root-soil is different, and the law of strength parameters versus δ of grafted soil of 365d is similar to that of planted soil of 90d. And the root reinforcement of grafted soil is weaker than planted soil. Hence the grafted soil can´t accurately reflect the root-soil interaction of the existing root system.

Influence of Freezing-Thawing on Shear Strength of Frozen Soil in Northeast China

2016 ◽  
Vol 835 ◽  
pp. 525-530 ◽  
Author(s):  
Rong Chen ◽  
Dong Zhe Li ◽  
Dong Xue Hao ◽  
Kai Li Wei
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Northeast China ◽  
Friction Angle ◽  
Frozen Soil ◽  
Internal Friction Angle ◽  
Silty Clay ◽  
Sharp Drop ◽  
Soil Cohesion

In order to study the influence of freezing-thawing cycles on shear strength of seasonal frozen soil in northeast China, silty clay, typical soil in Jilin region, was selected. 20 groups of specimens were carried out by quick shear tests considering soil water content and the number of freezing-thawing cycling. The test results indicate that soil cohesion presents the slight fluctuation with the increase of water content, and the maximum value reaches around the peak of liquid limit. Internal friction angle of soil shows the sharp drop and the extent changes between 40% - 60%. The soil cohesion gradually declines with the increase of the number of freeze-thawing cycling. Therefore, the effect of the first freezing-thawing cycle on soil cohesion is obvious, and cohesion gradually tend to be stable after 7 freezing-thawing cycles. The final value of cohesion is approximate a third to a half of the unfrozen soil. The internal friction angle of soil increases with the augment of cycling number of freezing-thawing, which is related to the water content. The higher water content will bring about the greater growth rate of friction angle.

scholarly journals Silicon Effects on the Root System of Diverse Crop Species Using Root Phenotyping Technology

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 885
Author(s):  
Pooja Tripathi ◽  
Sangita Subedi ◽  
Abdul Latif Khan ◽  
Yong-Suk Chung ◽  
Yoonha Kim
Keyword(s):  
Root System ◽  
Root Morphology ◽  
Morphological Traits ◽  
Crop Production ◽  
Spatial Configuration ◽  
Global Climate ◽  
Learning Technologies ◽  
Climate Change Scenarios ◽  
Crop Species ◽  
Wide Range

Roots play an essential function in the plant life cycle, as they utilize water and essential nutrients to promote growth and plant productivity. In particular, root morphology characteristics (such as length, diameter, hairs, and lateral growth) and the architecture of the root system (spatial configuration in soil, shape, and structure) are the key elements that ensure growth and a fine-tuned response to stressful conditions. Silicon (Si) is a ubiquitous element in soil, and it can affect a wide range of physiological processes occurring in the rhizosphere of various crop species. Studies have shown that Si significantly and positively enhances root morphological traits, including root length in rice, soybean, barley, sorghum, mustard, alfalfa, ginseng, and wheat. The analysis of these morphological traits using conventional methods is particularly challenging. Currently, image analysis methods based on advanced machine learning technologies allowed researchers to screen numerous samples at the same time considering multiple features, and to investigate root functions after the application of Si. These methods include root scanning, endoscopy, two-dimensional, and three-dimensional imaging, which can measure Si uptake, translocation and root morphological traits. Small variations in root morphology and architecture can reveal different positive impacts of Si on the root system of crops, with or without exposure to stressful environmental conditions. This review comprehensively illustrates the influences of Si on root morphology and root architecture in various crop species. Furthermore, it includes recommendations in regard to advanced methods and strategies to be employed to maintain sustainable plant growth rates and crop production in the currently predicted global climate change scenarios.

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