Collapse Behavior of Unsaturated Compacted Soils

2006 ◽  
Author(s):  
D. A. Sun ◽  
D. C. Sheng
Keyword(s):  
Compacted Soils ◽  
Collapse Behavior

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 Sandwich panel with in-plane honeycombs in different Poisson's ratio under low to medium impact loads

2021 ◽  
Vol 60 (1) ◽  
pp. 145-157
Author(s):  
Yi Luo ◽  
Ke Yuan ◽  
Lumin Shen ◽  
Jiefu Liu
Keyword(s):  
Poisson’S Ratio ◽  
Sandwich Panel ◽  
Impact Force ◽  
Impact Resistance ◽  
Poisson's Ratio ◽  
Compression Performance ◽  
Post Impact ◽  
Local Impact ◽  
Collapse Behavior ◽  
The Impact

Abstract In this study, a series of in-plane hexagonal honeycombs with different Poisson's ratio induced by topological diversity are studied, considering re-entrant, semi-re-entrant and convex cells, respectively. The crushing strength of honeycomb in terms of Poisson's ratio is firstly presented. In the previous research, we have studied the compression performance of honeycomb with different negative Poisson's ratio. In this study, a comparative study on the local impact resistance of different sandwich panels is conducted by considering a spherical projectile with low to medium impact speed. Some critical criteria (i.e. local indentation profile, global deflection, impact force and energy absorption) are adopted to analyze the impact resistance. Finally, an influential mechanism of Poisson's ratio on the local impact resistance of sandwich panel is studied by considering the variation of core strength and post-impact collapse behavior.

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.

scholarly journals Experimental Study and Development of Design Formula for Estimating the Ultimate Strength of Curved Plates

2021 ◽  
Vol 11 (5) ◽  
pp. 2379
Author(s):  
Jeong-Hyeon Kim ◽  
Doo-Hwan Park ◽  
Seul-Kee Kim ◽  
Myung-Sung Kim ◽  
Jae-Myung Lee
Keyword(s):  
Aspect Ratio ◽  
Ultimate Strength ◽  
Large Deflection ◽  
Slenderness Ratio ◽  
Compressive Load ◽  
Element Analysis ◽  
Shipbuilding Industry ◽  
Design Formula ◽  
Deflection Analysis ◽  
Collapse Behavior

The curved plate has been extensively used as a structural member in many industrial fields, especially the shipbuilding industry. The present study investigated the ultimate strength and collapse behavior of the simply supported curved plate under a longitudinal compressive load. To do this, experimental apparatuses for evaluating the buckling collapse test of the curved plates was developed. Then, a series of buckling collapse experiments was carried out by considering the flank angle, slenderness ratio, and aspect ratio of plates. To examine the fundamental buckling and collapse behavior of the curved plate, elastoplastic large deflection analysis was performed using the commercial finite element analysis program. On the basis of both the experimental and FE analysis, the effects of the flank angle, slenderness ratio, and aspect ratio on the characteristics of the buckling and collapse behavior of the curved plates are discussed. Finally, the empirical design formula for predicting the ultimate strength of curved plates was derived. The proposed empirical formula is a good indicator for estimating the behavior of the curved plate.

Proposal methodology to assess debris current design in traditional Chilean Bridges

2019 ◽  
Author(s):  
Matías A. Valenzuela ◽  
Francisco Hernandez ◽  
Nicolás A. Valenzuela ◽  
Flavio H. Álvarez ◽  
Hernan Pinto
Keyword(s):  
Code Design ◽  
Hydraulic Analysis ◽  
The Real ◽  
Newtonian Flows ◽  
Concrete Girders ◽  
The North ◽  
Current Design ◽  
Rain Fall ◽  
Collapse Behavior ◽  
Desert Zone

<p>During the last five years, the north of Chile was impacted by several natural disasters not considered in the traditional code design. During 2015 a great rain fall occurred in a desert zone, it is not prepared by this amount of water, producing soil and debris currents from the mountain to the sea (about 100 km).</p><p>These phenomena produced an important damage in the infrastructure, specially focused on roads and bridges. The main damage detected was the collapse of the infrastructure (piers and abutment) and the unlinking between deck and piers.</p><p>This paper presents a proposal methodology to assess the effect of these currents on bridges, using the case of study of the Chañaral Bridge, a multi-supported bridge, with four concrete girders, slab girder and two spans of 20 meters supported in two abutments and one concrete pier, over the Charañal River.</p><p>A sensitive hydraulic analysis via FEM was carried out using non-Newtonian flows (high density) representing the real final topography-condition of the current. A FEM of the bridge was carried out too considering a Non- Linear transient load. The inputs for model are the outputs from the hydraulic model in order to define the condition that produce the same collapse behavior showed after the real debris current.</p><p>Finally, results of this methodology are discussed, providing a comprehensive methodology, step by step, in order to obtained similar results according to the 2015 event.</p>

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