Experimental Study on Shear Strength of Root-Soil Composite of Different Grass and Shrub Plants in Three Gorges Reservoir Region

2013 ◽  
Vol 838-841 ◽  
pp. 981-986
Author(s):  
Mo Zhen Hu ◽  
Zhen Yao Xia ◽  
Yue Shu Yang ◽  
Li Deng ◽  
Xiao Pei Xu
Keyword(s):  
Shear Strength ◽  
Cynodon Dactylon ◽  
Plant Root ◽  
Reinforced Soil ◽  
Purple Soil ◽  
Soil Shear Strength ◽  
Plant Root System ◽  
The Relationship ◽  
Root Content ◽  
Peak Value

This paper discusses the relationship between shear strength of soil-root composite and root content of different plant species. The direct shear test of root - soil composite was made by grass and shrub plants -- alfalfa, Indigofera amblyatha, cynodon dactylon and purple soil .That how plant root system can improve the soil shear strength was analyzed. The results show that the shear strength of reinforced soil is increased. When the same plant root-soil composite is under the same root content, the shear strength is enhanced with the increase of normal stress. The peak value of shear strength appears in 0.4 - 0.5g per 60 cubic centimeter.

scholarly journals The mechanism of the plant roots’ soil-reinforcement based on generalized equivalent confining pressure

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10064
Author(s):  
Ping Guo ◽  
Zhenyao Xia ◽  
Qi Liu ◽  
Hai Xiao ◽  
Feng Gao ◽  
...  
Keyword(s):  
Shear Strength ◽  
Root Distribution ◽  
Plant Root ◽  
Friction Angle ◽  
Confining Pressure ◽  
Distribution Patterns ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Plant Roots ◽  
Root Content

Background To quantitatively evaluate the contribution of plant roots to soil shear strength, the generalized equivalent confining pressure (GECP), which is the difference in confining pressure between the reinforced and un-reinforced soil specimens at the same shear strength, was proposed and considered in terms of the function of plant roots in soil reinforcement. Methods In this paper, silt loam soil was selected as the test soil, and the roots of Indigofera amblyantha were chosen as the reinforcing material. Different drainage conditions (consolidation drained (CD), consolidation undrained (CU), and unconsolidated undrained (UU)) were used to analyse the influences of different root distribution patterns (horizontal root (HR), vertical root (VR), and complex root (CR)) and root contents (0.25%, 0.50%, and 0.75%) on the shear strength of soil-root composites. Results The cohesion (c) values of the soil-root composites varied under different drainage conditions and root contents, while the internal friction angle (φ ) values remain basically stable under different drainage conditions. Under the same root content and drainage conditions, the shear strength indexes ranked in order of lower to higher were HR, VR and CR. The GECP of the soil-root composites with a 0.75% root content was 1.5–2.0 times that with a 0.50% root content and more than 5 times that with a 0.25% root content under the CD and CU conditions. The GECP in reinforced soil followed the sequence of CD > CU > UU. The GECP of the plant roots increased as confining pressure increased under CD and CU conditions while showed a complex change to the confining pressure under the UU condition. Conclusion It was concluded that the evaluation of plant root reinforcing soil based on GECP can be used to measure effectively the influences of roots on soil under different drainage conditions and root distribution patterns.

Influence of root fractal dimension on soil shear strength with 3D printing method

2020 ◽  
Author(s):  
jun li ◽  
yan zhang
Keyword(s):  
Shear Strength ◽  
Fractal Dimension ◽  
3D Printing ◽  
Internal Friction ◽  
Root System ◽  
Plant Root ◽  
Triaxial Compression ◽  
Soil Shear Strength ◽  
The Relationship ◽  
Printing Method

<p>The rapid development of expressway provide convenience for our life. But during the construction and operation, the slope instability is a serious ecological problems which can threat the normal use of the expressway. As slope protection is essential, the ecological slope protection is an environmental friendly method to reinforce the slope stability as the root can make contribution to the soil shear strength. From the macro perspective, the soil reinforced ability of root system is greatly affected by the structure and distribution morphology of plant root system. So it is crucial to study the influence of root distribution characteristics on the soil shear strength. As the structure of plant root has typical fractal feature, fractal dimension which is the most important quantitative parameter is chosen to establish the relationship with the soil strength. Because the structure of the plant roots is very complex and no two roots are identical, it is difficult to find the same root to conduct contrast tests. But at least four tests with different cell pressures are essential to obtain the cohesion and internal friction angel. Thus 3d printing method is a superior choice to ensure each test condition is as same as possible. The purpose of this study is to explore the relationship between the root fractal dimension and soil cohesion, and internal friction angel. In order to reduce the influence of root difference on the triaxial compression test, 3D printing method is applied to make simulative plant roots which can maintain the fractal dimension. So single variable experiment could be guaranteed, the general rule between fractal dimension of root system and soil reinforced ability can be revealed. Four roots of Cynodon dactylon with different fractal dimension were chosen to establish 3D printing model. Corresponding to each fractal dimension, four triaxial compression test were conducted with four cell pressure. The results indicate that both of the cohesion and internal friction rise with the increasing of the fractal dimension, but the influence of fractal dimension on cohesion is slight compared with the influence on the internal friction. That is to say, the root with larger fractal dimension possess better reinforced effect on slope soil by increasing the the internal friction.</p>

Shear Strength Monitoring System Based on Measurement of Shear Wave Velocity and Moisture Content

2014 ◽  
Vol 635-637 ◽  
pp. 750-754
Author(s):  
Peng Hu ◽  
Qing Li ◽  
Yi Wei Xu ◽  
Nan Ying Shentu ◽  
Quan Yuan Peng
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Shear Wave ◽  
Monitoring System ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Elements ◽  
Strength Measurement ◽  
Soil Shear Strength ◽  
The Relationship

Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

Soil Shear Strength Characteristic in Slope Disintegration Area

2013 ◽  
Vol 353-356 ◽  
pp. 735-739
Author(s):  
Xiao Ming Zhang ◽  
Shu Wen Ding ◽  
Shuang Xi Li
Keyword(s):  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Clay Content ◽  
Scientific Basis ◽  
Soil Mechanic ◽  
Direct Shear ◽  
Soil Cohesion ◽  
Soil Shear Strength ◽  
The Relationship

Development of slope disintegration is close to soil mechanic characteristics such as shear strength indices. Soil grain diameter and water content were tested. Soil direct shear test was conducted to analyze the relationship between shear strength indices and the influencing factors. The experimental data indicate that clay content and the range affect soil cohesion value and the scope. Soil cohesion increases with bulk density before 1.6g/cm3. But it decreases when the bulk after that. The results could provide a scientific basis for control of slope disintegration.

scholarly journals Measuring the Strength of Root-Reinforced Soil on Steep Natural Slopes Using the Corkscrew Extraction Method

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1135 ◽  
Author(s):  
Gerrit Meijer ◽  
Glyn Bengough ◽  
Jonathan Knappett ◽  
Kenneth Loades ◽  
Bruce Nicoll
Keyword(s):  
Shear Strength ◽  
Soil Analysis ◽  
Soil Strength ◽  
Effective Field ◽  
Reinforced Soil ◽  
Wind Loading ◽  
Rapid Estimation ◽  
Soil Shear Strength ◽  
Soil Component ◽  
Natural Slopes

Roots can help to stabilise slopes against landslides and anchor trees against wind loading, but their mechanical contribution to the strength of soil is difficult to rapidly quantify under field conditions. A new field measurement method, quantifying the shear strength of rooted soil by measuring the resistance against extraction of soil cores using a large corkscrew device, was tested across three heterogeneous slopes (unforested, forested and clearfelled) in Scotland. The presence of roots significantly increased the measured shear strength in the surface layer of the Sitka spruce forested slope. Differences in strength between the three areas were however not significant. This could be attributed to the large variation in the soil component of the combined root–soil shear strength, which was strongly affected by variations in both soil density and gravel content. Measured strength on these natural slopes were much more variable compared to previously investigated sites. These results highlight the importance of investigating the variation in soil strength during root-reinforcement measurements, and furthermore demonstrate the need for a sufficiently large number of tests to address this variation. The corkscrew provides rapid estimation of root-reinforced soil shear strength on sites with difficult accessibility. Compared to the more conventional shear vane method, which yielded comparable soil strength results, the corkscrew proved more suitable in stony soil layers and has the additional benefit of simultaneously extracting small (rooted) soil samples that could be used for further root and soil analysis. It therefore proved a useful and effective field tool for use when a rapid estimation of root-reinforced soil shear strength is required.

scholarly journals Measurement of Peat Soil Shear Strength Using Wenner Four-Point Probes and Vane Shear Strength Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Irfan Ahmad Afip ◽  
Siti Noor Linda Taib ◽  
Kamaruzaman Jusoff ◽  
Liyana Ahmad Afip
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Soil Salinity ◽  
Peat Soil ◽  
Undrained Shear Strength ◽  
Soil Resistivity ◽  
In Situ Test ◽  
Soil Shear Strength ◽  
The Relationship

The general objective of this research was to measure the peat soil shear strength using Wenner four-point probes and vane shear strength methods. Specifically, the objective of this study was two-fold, namely, (a) investigating the relationship between laboratory soil resistivity and undrained shear strength and (b) determineing the relationship between in-situ soil resistivity and undrained shear strength. Data were randomly collected over six locations in Meranek, Sarawak, for in-situ test and three repetitions for each data were set based on three parameters. The selected parameters were soil density, moisture content, and salinity for both laboratory and in-situ test using Wenner four-point probes and vane shear method. The soil resistivity and vane shear strength readings for laboratory test were correlated with soil salinity, moisture content, and density. The R2 values showed a good correlation for soil salinity (R2 =0.8468) and density (R2 =0.9475), respectively. However, a weak correlation of R2 =0.1205 was observed for soil moisture. The R2 value for in-situ correlation between soil resistivity and three parameters (soil salinity, moisture content, and density) was R2 =0.8916. It can be concluded that the peat soil shear strengths of the study area using Wenner four-point probes from in-situ were (4.38 ohm.m) and laboratory was (2.47 ohm.m) and when using the vane shear strength method, in-situ was (23 kPA) and laboratory was (5 kPA). This study implies that the peat soil of the study area can be categorized as texture (soft loamy soil) and it is suitable for agriculture instead of construction. The relationship established between Wenner four-point probes and vane shear method can be beneficial for ground engineering design to enhance investigation on site suitability. Future work on DUALEM-421 technique should be emphasised for better subsurface exploration accuracy and resolve peat depth for an in-situ test.

Soil Shear Strength Enhancements from Plant Root Templated Georeinforcements

2012 ◽  
Author(s):  
Drew W. Johnson ◽  
Miguelangel Sauceda ◽  
Sazzad Bin-Shafique ◽  
Jie Huang
Keyword(s):  
Shear Strength ◽  
Plant Root ◽  
Soil Shear Strength

Shear Strength Change of Different Water Content after Thawing Remolded Soil

2012 ◽  
Vol 204-208 ◽  
pp. 334-337
Author(s):  
Wei Jiang ◽  
Bing Xin Gu
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Room Temperature ◽  
Triaxial Compression ◽  
Shear Strength Parameters ◽  
Strength Change ◽  
Soil Shear Strength ◽  
Set Up ◽  
Relationship Of ◽  
The Relationship

Freeze-thaw made the microstructure of the soil produce a certain degree of damage, which was relevant with the soil water content. 6 kinds of remolded soil of the water content was prepared, at low temperature of freezed, in room temperature of melt, after not consolidated non-drained triaxial compression test, the soil shear strength parameters was determined. The results show: after thawed, soil shear strength had reduced significantly, and water content exerted such a pronounced effect on strength of reducing amplitude. Accordingly, the relationship of shear strength reducing after thawing of remolded soil and the water content was set up preliminarily.

The main influencing factors of soil mechanical characteristics of the gravity erosion environment in the dry-hot valley of Jinsha river

2018 ◽  
Vol 16 (1) ◽  
pp. 796-809 ◽  
Author(s):  
Yangyi Zhao ◽  
Xu Duan ◽  
Jiaojiao Han ◽  
Kun Yang ◽  
Yang Xue
Keyword(s):  
Shear Strength ◽  
Soil Erosion ◽  
Root System ◽  
Mechanical Characteristics ◽  
Plant Root ◽  
Friction Angle ◽  
Plant Root System ◽  
The Impact ◽  
Erosion Environment ◽  
Mass Erosion

AbstractThe dry-hot valley region counts as one of the most eco-sensitive zones in China, the issue of soil erosion is critical in regional ecological environment, soil mechanical property is one of the primary factors confining the occurrence of erosion, and it is attached crucial significance to in ascertaining the characteristics and principal factors of soil mechanics, and how to prevent and control soil erosion in arid red soil area of dry-hot valley. Through monitoring field location and directly shearing, the soil mechanical characteristics and the primary influencing factors of the mass erosion environment in the basin were ascertained. As the result indicates: (1) The soil moisture content, cohesion and internal friction angle are evidently correlated with each other abiding by power function, the relationship among soil cohesion, internal friction angle and volume moisture content goes as:$$\begin{array}{} \displaystyle c=80.107e^{-5.451\frac{{\it\omega}}{1.64\,+\,{\it\omega}}},\phi=65.646{\rm e}^{-3.325\frac{\omega}{1.64\,+\,\omega}}; \end{array}$$(2) The soil being large in pore radius vary in number and distribution evidently with structure and destruction degree (P<0.05). Soil aggregation was also significantly different (P<0.05), with the increasing of structural failure rate, the shear strength of soil decreased, and the probability of damage was increased as the external load increaseing. (3) The disintegration of soil can be effectively decelerated, and anti-disintegration ability of soil can be enhanced by the root system. The impact exerted by plant root system on shear strength of soil decreased as soil got deeper, more than a certain depth can be ignored; the impact exerted by plant root system on small-scale gravitational erosion was particularly evident, whereas the impact exerted by large-scale mass erosion was comparatively small. The ability of plant roots to optimize soil resistance was primarily through the roots shorter than 2 mm, the effective fibrous roots in the soil of the Leucaena Benth and the Dodonaea angustifolia were comparatively small, and the root of the herbaceous plants was comparatively large.

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