The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Xiaodong Ji - One of the best experts on this subject based on the ideXlab platform.
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triaxial compression test of Soil root composites to evaluate influence of roots on Soil Shear Strength
Ecological Engineering, 2010Co-Authors: Chaobo Zhang, Lihua Chen, Xiaodong JiAbstract:Abstract In order to evaluate influences of roots on Soil Shear Strength, a triaxial compression test was carried out to study the Shear Strength of plain Soil samples and composites comprised of roots of Robinia pseucdoacacia and Soil from the Loess Plateau in Northwest China. Roots were distributed in Soil in three forms: vertical, horizontal, and vertical–horizontal (cross). All samples were tested under two different Soil water contents. Test results showed that roots have more impacts on the Soil cohesion than the friction angle. The presence of roots in Soil substantially increased the Soil Shear Strength. Among three root distribution forms, the reinforcing effect of vertical–horizontal (cross) root distribution was the most effective. Increase in Soil water content directly induced a decline in Soil cohesion of all test samples and resulted in a decrease in Shear Strength for both plain Soil samples and Soil–root composites. It was concluded that the triaxial compression test can be effectively used to study influences of roots on Soil Shear Strength.
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Triaxial compression test of Soil–root composites to evaluate influence of roots on Soil Shear Strength
Ecological Engineering, 2009Co-Authors: Chaobo Zhang, Lihua Chen, Xiaodong JiAbstract:Abstract In order to evaluate influences of roots on Soil Shear Strength, a triaxial compression test was carried out to study the Shear Strength of plain Soil samples and composites comprised of roots of Robinia pseucdoacacia and Soil from the Loess Plateau in Northwest China. Roots were distributed in Soil in three forms: vertical, horizontal, and vertical–horizontal (cross). All samples were tested under two different Soil water contents. Test results showed that roots have more impacts on the Soil cohesion than the friction angle. The presence of roots in Soil substantially increased the Soil Shear Strength. Among three root distribution forms, the reinforcing effect of vertical–horizontal (cross) root distribution was the most effective. Increase in Soil water content directly induced a decline in Soil cohesion of all test samples and resulted in a decrease in Shear Strength for both plain Soil samples and Soil–root composites. It was concluded that the triaxial compression test can be effectively used to study influences of roots on Soil Shear Strength.
Bart Muys - One of the best experts on this subject based on the ideXlab platform.
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root tensile Strength and root distribution of typical mediterranean plant species and their contribution to Soil Shear Strength
Plant and Soil, 2008Co-Authors: S De Baets, Jean Poesen, Bert Reubens, K Wemans, J De Baerdemaeker, Bart MuysAbstract:In Mediterranean environments, gully erosion is responsible for large Soil losses. It has since long been recognized that slopes under vegetation are much more resistant to Soil erosion processes compared to bare Soils and improve slope stability. Planting or preserving vegetation in areas vulnerable to erosion is therefore considered to be a very effective Soil erosion control measure. Re-vegetation strategies for erosion control rely in most cases on the effects of the above-ground biomass in reducing water erosion rates, whereas the role of the below-ground biomass is often neglected or underestimated. While the above-ground biomass can temporally disappear in semi-arid environments, roots may still be present underground and play an important role in protecting the topSoil from being eroded. In order to evaluate the potential of plant species growing in Mediterranean environments to prevent shallow mass movements on gully or terrace walls, the root reinforcement effect of 25 typical Mediterranean matorral species (i.e. shrubs, grasses herbs, small trees) was assessed, using the simple perpendicular model of Wu et al. (Can Geotech J 16:19–33, 1979). As little information is available on Mediterranean plant root characteristics, root distribution data were collected in SE-Spain and root tensile Strength tests were conducted in the laboratory. The power root tensile Strength–root diameter relationships depend on plant species. The results show that the shrubs Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. have the strongest roots, followed by the grass Brachypodium retusum (Pers.) Beauv. The shrubs Nerium oleander L. and the grass Avenula bromoides (Gouan) H. Scholz have the weakest roots in tension. Root area ratio for the 0–0.1 m topSoil ranges from 0.08% for the grass Piptatherum miliaceum (L.) Coss to 0.8% for the tree Tamarix canariensis Willd. The rush Juncus acutus L. provides the maximum Soil reinforcement to the topSoil by its roots (i.e. 304 kPa). Grasses also increase Soil Shear Strength significantly (up to 244 kPa in the 0–0.1 m topSoil for Brachypodium retusum (Pers.) Beauv.). The shrubs Retama sphaerocarpa (L.) Boiss. and Anthyllis cytisoides L. are increasing Soil Shear Strength to a large extent as well (up to 134 and 160 kPa respectively in the 0–0.10 m topSoil). Whereas grasses and the rush Juncus acutus L. increase Soil Shear Strength in the topSoil (0–0.10 m) to a large extent, the shrubs Anthyllis cytisoides (L.), Retama sphaerocarpa (L.) Boiss., Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. strongly reinforce the Soil to a greater depth (0–0.5 m). As other studies reported that Wu’s model overestimates root cohesion values, reported root cohesion values in this study are maximum values. Nevertheless, the calculated cohesion values are used to rank species according to their potential to reinforce the Soil.
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Root tensile Strength and root distribution of typical Mediterranean plant species and their contribution to Soil Shear Strength
Plant and Soil, 2008Co-Authors: S De Baets, Jean Poesen, Bert Reubens, K Wemans, J De Baerdemaeker, Bart MuysAbstract:In Mediterranean environments, gully erosion is responsible for large Soil losses. It has since long been recognized that slopes under vegetation are much more resistant to Soil erosion processes compared to bare Soils and improve slope stability. Planting or preserving vegetation in areas vulnerable to erosion is therefore considered to be a very effective Soil erosion control measure. Re-vegetation strategies for erosion control rely in most cases on the effects of the above-ground biomass in reducing water erosion rates, whereas the role of the below-ground biomass is often neglected or underestimated. While the above-ground biomass can temporally disappear in semi-arid environments, roots may still be present underground and play an important role in protecting the topSoil from being eroded. In order to evaluate the potential of plant species growing in Mediterranean environments to prevent shallow mass movements on gully or terrace walls, the root reinforcement effect of 25 typical Mediterranean matorral species (i.e. shrubs, grasses herbs, small trees) was assessed, using the simple perpendicular model of Wu et al. (Can Geotech J 16:19-33, 1979). As little information is available on Mediterranean plant root characteristics, root distribution data were collected in SE-Spain and root tensile Strength tests were conducted in the laboratory. The power root tensile Strength-root diameter relationships depend on plant species. The results show that the shrubs Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. have the strongest roots, followed by the grass Brachypodium retusum (Pers.) Beauv. The shrubs Nerium oleander L. and the grass Avenula bromoides (Gouan) H. Scholz have the weakest roots in tension. Root area ratio for the 0-0.1 m topSoil ranges from 0.08% for the grass Piptatherum miliaceum (L.) Coss to 0.8% for the tree Tamarix canariensis Willd. The rush Juncus acutus L. provides the maximum Soil reinforcement to the topSoil by its roots (i.e. 304 kPa). Grasses also increase Soil Shear Strength significantly (up to 244 kPa in the 0-0.1 m topSoil for Brachypodium retusum (Pers.) Beauv.). The shrubs Retama sphaerocarpa (L.) Boiss. and Anthyllis cytisoides L. are increasing Soil Shear Strength to a large extent as well (up to 134 and 160 kPa respectively in the 0-0.10 m topSoil). Whereas grasses and the rush Juncus acutus L. increase Soil Shear Strength in the topSoil (0-0.10 m) to a large extent, the shrubs Anthyllis cytisoides (L.), Retama sphaerocarpa (L.) Boiss., Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. strongly reinforce the Soil to a greater depth (0-0.5 m). As other studies reported that Wu's model overestimates root cohesion values, reported root cohesion values in this study are maximum values. Nevertheless, the calculated cohesion values are used to rank species according to their potential to reinforce the Soil.status: publishe
Chaobo Zhang - One of the best experts on this subject based on the ideXlab platform.
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triaxial compression test of Soil root composites to evaluate influence of roots on Soil Shear Strength
Ecological Engineering, 2010Co-Authors: Chaobo Zhang, Lihua Chen, Xiaodong JiAbstract:Abstract In order to evaluate influences of roots on Soil Shear Strength, a triaxial compression test was carried out to study the Shear Strength of plain Soil samples and composites comprised of roots of Robinia pseucdoacacia and Soil from the Loess Plateau in Northwest China. Roots were distributed in Soil in three forms: vertical, horizontal, and vertical–horizontal (cross). All samples were tested under two different Soil water contents. Test results showed that roots have more impacts on the Soil cohesion than the friction angle. The presence of roots in Soil substantially increased the Soil Shear Strength. Among three root distribution forms, the reinforcing effect of vertical–horizontal (cross) root distribution was the most effective. Increase in Soil water content directly induced a decline in Soil cohesion of all test samples and resulted in a decrease in Shear Strength for both plain Soil samples and Soil–root composites. It was concluded that the triaxial compression test can be effectively used to study influences of roots on Soil Shear Strength.
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Triaxial compression test of Soil–root composites to evaluate influence of roots on Soil Shear Strength
Ecological Engineering, 2009Co-Authors: Chaobo Zhang, Lihua Chen, Xiaodong JiAbstract:Abstract In order to evaluate influences of roots on Soil Shear Strength, a triaxial compression test was carried out to study the Shear Strength of plain Soil samples and composites comprised of roots of Robinia pseucdoacacia and Soil from the Loess Plateau in Northwest China. Roots were distributed in Soil in three forms: vertical, horizontal, and vertical–horizontal (cross). All samples were tested under two different Soil water contents. Test results showed that roots have more impacts on the Soil cohesion than the friction angle. The presence of roots in Soil substantially increased the Soil Shear Strength. Among three root distribution forms, the reinforcing effect of vertical–horizontal (cross) root distribution was the most effective. Increase in Soil water content directly induced a decline in Soil cohesion of all test samples and resulted in a decrease in Shear Strength for both plain Soil samples and Soil–root composites. It was concluded that the triaxial compression test can be effectively used to study influences of roots on Soil Shear Strength.
Willy Z. Sadeh - One of the best experts on this subject based on the ideXlab platform.
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surface cleanliness effect on lunar Soil Shear Strength
Journal of Geotechnical and Geoenvironmental Engineering, 2001Co-Authors: Howard A. Perko, John D. Nelson, Willy Z. SadehAbstract:Lunar Soil consists of dry silty sand. Observations and measurements conducted during Surveyor, Apollo, and Luna missions indicated that the lunar Soil is unusually cohesive. This is attributable to the fact that thick layers of adsorbed gases, which coat and lubricate Soil particles on Earth, are absent in the ultrahigh vacuum on the Moon. “Surface cleanliness” is introduced as a new parameter for describing Soils in different planetary environments. It is defined as the dimensionless inverse of adsorbate thickness on solid surfaces. By this definition, the ultrahigh vacuum on the Moon is associated with high surface cleanliness, while Earth's atmosphere is associated with low surface cleanliness. A model is developed to calculate surface cleanliness and its effect on Shear Strength in any planetary environment. Results obtained from the model compare well with data from previous ultrahigh vacuum and variable temperature laboratory experiments on Earth Soils. It is shown that surface cleanliness is an im...
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Surface Cleanliness Effects on Lunar Regolith Shear Strength
Engineering Construction and Operations in Space V, 1996Co-Authors: Howard A. Perko, John D. Nelson, Willy Z. SadehAbstract:A study of the influence of surface cleanliness on the geotechnical properties of lunar regolith was undertaken. Surface cleanliness and its effect on Soil Shear Strength were evaluated by applying a recently developed model. Results indicate that a significant portion of lunar Soil Shear Strength is induced by the surface cleanliness. Surface cleanliness considerations for lunar base design are discussed.
Jinlin Li - One of the best experts on this subject based on the ideXlab platform.
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Shear Strength of purple Soil bunds under different Soil water contents and dry densities a case study in the three gorges reservoir area china
Catena, 2018Co-Authors: Jinlin Li, Shasha Li, Xiubin HeAbstract:Abstract Purple Soil bunds are embankments constructed along the contour on purple Soil sloping farmlands, and play a key role in controlling Soil erosion. The Soil Shear Strength makes a significant influence to the bund stability; however, few reports have documented how purple Soil Shear Strength responds to the Soil physical properties. The main goal of the present study was to determine how indicators of Soil Shear Strength vary with the Soil water content and dry density. In this study, we collected Soil samples from 3 purple Soil bunds in Zhong County, in the Three Gorges Reservoir Area in China, and performed an unconsolidated undrained triaxial compression test to study the Soil Shear Strength in terms of the cohesion (c), internal friction angle (φ), and the principal stress difference (σ1–σ3). The test results show that when the dry density was constant and the Soil water content increased, the Soil cohesion increased and then decreased, and the results fitted to a quadratic curve. As the Soil water content increased, the internal friction angle of the Soil bunds decreased and displayed a first-order exponential decay. As the Soil water content increased and the confining pressure remained constant, the principal stress difference decreased rapidly. When the Soil water content was constant and the dry density increased, the Soil cohesion, internal friction angle, and the total principal stress difference increased, although at different rates. In general, the water content had a greater effect on the cohesion, internal friction angle, and the principal stress difference than the dry density, but there were little or no interaction between water content and dry density. Furthermore, except when the water content was 6%, the stress–strain characteristics were similar across the range of water contents. For a low water content, fixed confining pressure, and an increasing dry density, the curves gradually changed from the hardening type to the weak hardening type and then to the softening type. In most cases the curves corresponded with the hardening type as the confining pressure increased.
