MARS Use in Prediction of Collapse Potential for Compacted Soils

2019 ◽  
pp. 27-46 ◽  
Author(s):  
Wengang Zhang
Keyword(s):  
Compacted Soils ◽  
Collapse Potential

Growth of Ornamental Plants in Compacted Soils in Relation to Root Growth under Low Oxygen and High Atmospheric Pressure

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 479d-479
Author(s):  
Michael Knee ◽  
Ruth Brake
Keyword(s):  
Atmospheric Pressure ◽  
Root Elongation ◽  
Native Plants ◽  
Tagetes Patula ◽  
Low Oxygen ◽  
Compacted Soils ◽  
Bedding Plants ◽  
Four Levels ◽  
Physical Resistance ◽  
High Atmospheric Pressure

In urban situations, particularly after construction, herbaceous ornamentals may be planted into soils that are compacted or have poor structure so that plant roots may encounter poor aeration or physical resistance. Low oxygen concentrations may be the most important aspect of poor aeration and are readily reproduced in the laboratory. High atmospheric pressure might be used to screen for the ability to grow against physical resistance. We tested the suggestion that “native” plants would grow better in compacted soils than typical bedding plants and for differences in tolerance to low oxygen or high pressure. Plants were grown from seed in the greenhouse at four levels of compaction in peat-based medium and in field soil. Shoot dry weights of the native plants Asclepias tuberosa, Echinacea purpurea, and Schizachyrium scoparius, were less affected by growth in compacted soil or peat medium than those of the bedding plants, Antirrhinum majus, Gypsophila elegans, Impatiens balsamina, Tagetes patula and Zinnia elegans. The oxygen content of media declined with compaction to a minimum of 10 kPa. Half maximal root elongation was observed at 1 to 3 kPa oxygen for most species without any separation between the groups. A presure of 1100 kPa reduced root elongation of the bedding plants by 50 to 70% but only 5 to 20% for the native plants.

scholarly journals Evaluation of Leaf Litter Mulching and Incorporation on Skid Trails for the Recovery of Soil Physico-Chemical and Biological Properties of Mixed Broadleaved Forests

Land ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 625
Author(s):  
Meghdad Jourgholami ◽  
Azadeh Khoramizadeh ◽  
Angela Lo Monaco ◽  
Rachele Venanzi ◽  
Francesco Latterini ◽  
...  
Keyword(s):  
Soil Properties ◽  
Soil Compaction ◽  
Biological Properties ◽  
Soil Protection ◽  
Natural Soil ◽  
Compacted Soils ◽  
Beneficial Effects ◽  
Physico Chemical ◽  
Forest Logging ◽  
Soil Recovery

Engineering applications can be used to mitigate the adverse effects of soil compaction and amend compacted soils. Previous literature has highlighted the beneficial effects of interventions such as litter mulching and incorporation on skid trails. However, little is known about the effectiveness of these alternatives in restoring forest soil quality after forest logging. The objective of this study was to properly elucidate the effects of the above mentioned soil protection methods, litter incorporation before skidding (LI) and litter mulching after skidding (LM), on the recovery of compacted soil’s physico-chemical and biological properties on skid trails over a 2-year period in the Hyrcanian forests of Iran to identify the best option for restoration intervention. The litter used in both methods consisted of dried leaves of the hornbeam and maple tree in three intensities of 3, 6, and 9 Mg ha−1. The results showed that the application of both methods (LI and LM) significantly improved the soil properties when compared to the untreated skid trail. Results showed that the recovery values of soil properties in the LI treatments were significantly higher than those of the LM. The recovery values of soil properties by 6 and 9 Mg ha−1 were significantly higher than those of 3 Mg ha−1, while the differences were not significant between 6 and 9 Mg ha−1. Our findings showed that soil properties were partially recovered (70–80%) over a 2-year period from treatment, compared to untreated, but the full recovery of soil properties required more time to return to the pre-harvest value. Overall, the results of this study demonstrated that the application of soil protection methods accelerates the process of recovering soil properties much faster than natural soil recovery, which can take more than 20 years in these forests.

Tensile Strength of Compacted Soils

1970 ◽  
Vol 96 (6) ◽  
pp. 2185-2190
Author(s):  
Jagdish Narain ◽  
Prakash C. Rawat
Keyword(s):  
Tensile Strength ◽  
Compacted Soils

Dry unit weight of compacted soils prediction using GMDH-type neural network

2017 ◽  
Vol 132 (8) ◽  
Author(s):  
Mahmoud Hassanlourad ◽  
Alireza Ardakani ◽  
Afshin Kordnaeij ◽  
Hossein Mola-Abasi
Keyword(s):  
Neural Network ◽  
Unit Weight ◽  
Compacted Soils ◽  
Dry Unit Weight

scholarly journals State-of-the-Art-Review of Collapsible Soils

2000 ◽  
Vol 5 ◽  
pp. 115 ◽  
Author(s):  
A. A. AL-Rawas
Keyword(s):  
Field Tests ◽  
Clay Content ◽  
Field Testing ◽  
Dry Density ◽  
Foundation Design ◽  
Treatment Methods ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Different Types ◽  
Compaction Control

Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.

scholarly journals Numerical Study on the Behavior and Bearing Mechanism of Flat Slabs in Column Loss Events

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Aidin Mohammadi ◽  
Alireza Pachenari ◽  
Behnam Sadeghi
Keyword(s):  
Numerical Study ◽  
Progressive Collapse ◽  
Great Tendency ◽  
Load Bearing ◽  
Collapse Potential ◽  
Flat Slabs ◽  
Collapse Mode ◽  
Damaged Zone ◽  
Initial Load ◽  
Cracking Pattern

This study investigates the behavior and the load-bearing mechanism of a typical flat slab with rectangular panels in several scenarios including the removal of a corner, penultimate, and internal columns. The scenarios are rather similar to those used in the conventional evaluation of the progressive collapse potential; however, application of the uniformly distributed loading over panels adjacent to the removed columns was not limited to twice the value of the initial load. Thus, load-deflection curves were drawn up to the point in which a great number of longitudinal slab bars ruptured. Introducing 5 stages on each curve, finite element outputs on concrete cracking pattern and rebar stress state were presented. A significant increase in the stresses along the diagonals of the slab panels accompanied by bar ruptures around columns adjacent to the removed column proved contribution of an important load-bearing mechanism in addition to the behavior called “quasiframe action.” Consecutive rupture of bars showed formation of a zipper-type collapse mode as well as a great tendency to transfer load share of missing column mainly along shorter direction of slab panels. Moreover, the findings indicated that the slab damaged zone could exceed the panels under uniform overloading.

scholarly journals Diversity of arbuscular mycorrhizal fungi (amf) in three agroecosystems with grass colosoana (Bothriochloa pertusa (L) A. Camus) in the department of Sucre

2016 ◽  
Vol 8 (1) ◽  
pp. 72
Author(s):  
FREDIS ESPITIA D ◽  
ALEXANDER PEREZ C
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Soil Samples ◽  
Compacted Soils ◽  
San Marcos

The present study evaluated the diversity of arbuscular mycorrhizal fungi (AMF) associated soils from three ecosystems grown with pasture colosoana in three localities of the Department of Sucre, Colombia. Soil samples were collected, AMF spores isolated, count of spore was made and morphotypes isolated were classification at the level of species or genera. We found that the genus of AMF over prevailing in native and compacted soils in the three selected municipalities is the genus Glomus, followed by other genera to a lesser extent. In general the soils that presented greater wealth of genres of HMA were those of the municipality of San Marcos, while the lowest richness was found in the municipality of Sincelejo.

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