Experimental Study of Hysteresis in Clayey Soils under Compression

2022 ◽  
Vol 906 ◽  
pp. 107-113
Author(s):  
Tigran Petrosyan ◽  
Sargis Khachatryan ◽  
Namat Namatyan
Keyword(s):  
Absorption Coefficient ◽  
Hysteresis Loop ◽  
Clay Soil ◽  
Sandy Loam ◽  
Cyclic Stress ◽  
Dissipated Energy ◽  
Loop Formation ◽  
Fourth Series ◽  
Series Of Experiments ◽  
Loading Modes

The energy dissipation for one cycle of clay soil deformation over the area of ​​a hysteresis loop under conditions of one-dimensional deformation has been experimentally studied. Several series of trials were carried out under different conditions of soil density and moisture and different loading modes. It was established by the experiments that after several cycles of loading and unloading of the samples, the transient process of the closed loop formation ends and certain dependences of stress on deformations are established in the sections of the ascending and descending branches of the hysteresis loop. To determine these dependencies, rheological relations obtained directly from the hysteresis loop by approximating the arcs of its contour have been used. By integrating the approximating rheological dependences along the branches of the loop, the dissipated energy per deformation cycle has been obtained as a function of cyclic deformation amplitude, measured by the area of the hysteresis loop. Experiments on obtaining a hysteresis loop were carried out on a compression device with a cyclic sample. Samples with different states of density and moisture content were produced by consolidating a paste having yield point moisture under different pressures. Several series of experiments have been carried out. In the first series, soil absorption coefficients were derived for different states of density-moisture at different loading rates. In the second series, three types of clayish soil (clay, loam, sandy loam) were studied. Dissipation coefficients have been found out for the indicated soils. In the third series, three types of clay soil were tested under different conditions of density and moisture. The dissipation coefficients have been obtained. In the fourth series, the dependences of the absorption coefficient on the amplitude value of the cyclic stress for three types of clay soil were disclosed. It was found that a change in the loading rate within the range from 0.05 MPa to 0.2 MPa does not lead to the significant change in the absorption coefficient, the increase in the number of clay fractions in the sample leads to an increase in the absorption coefficient, a change in the amplitude of cyclic loading (in the indicated range of change) does not affect the absorption coefficient.

scholarly journals Soil Texture Alters the Impact of Salinity on Carbon Mineralization

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 128
Author(s):  
Ruihuan She ◽  
Yongxiang Yu ◽  
Chaorong Ge ◽  
Huaiying Yao
Keyword(s):  
Soil Texture ◽  
Clay Soil ◽  
Sandy Loam ◽  
Microbial Community Composition ◽  
Clay Content ◽  
Interactive Effects ◽  
Silty Clay ◽  
C Mineralization ◽  
Negative Effect ◽  
Silty Clay Soil

Soil salinization typically inhibits the ability of decomposer organisms to utilize soil organic matter, and an increase in soil clay content can mediate the negative effect of salinity on carbon (C) mineralization. However, the interactive effects of soil salt concentrations and properties on C mineralization remain uncertain. In this study, a laboratory experiment was performed to investigate the interactive effects of soil salt content (0.1%, 0.3%, 0.6% and 1.0%) and texture (sandy loam, sandy clay loam and silty clay soil with 6.0%, 23.9% and 40.6% clay content, respectively) on C mineralization and microbial community composition after cotton straw addition. With increasing soil salinity, carbon dioxide (CO2) emissions from the three soils decreased, but the effect of soil salinity on the decomposition of soil organic carbon varied with soil texture. Cumulative CO2 emissions in the coarse-textured (sandy loam and sandy clay loam) soils were more affected by salinity than those in the fine-textured (silty clay) soil. This difference was probably due to the differing responses of labile and resistant organic compounds to salinity across different soil texture. Increased salinity decreased the decomposition of the stable C pool in the coarse-textured soil, by reducing the proportion of fungi to bacteria, whereas it decreased the mineralization of the active C pool in the fine-textured soil through decreasing the Gram-positive bacterial population. Overall, our results suggest that soil texture controlled the negative effect of salinity on C mineralization through regulating the soil microbial community composition.

Effects of water stress and soil type on photosynthesis, leaf water potential and yield of olive trees (Olea europaea L. cv. Chemlali Sfax)

2007 ◽  
Vol 47 (12) ◽  
pp. 1484 ◽  
Author(s):  
B. Ben Rouina ◽  
A. Trigui ◽  
R. d'Andria ◽  
M. Boukhris ◽  
M. Chaïeb
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Sandy Soil ◽  
Clay Soil ◽  
Sandy Loam ◽  
Leaf Water ◽  
Severe Drought ◽  
Relative Water ◽  
Olive Trees

In Tunisia, olives are grown under severe rain-fed, arid conditions. To determine the behaviour of olive trees (cv. Chemlali Sfax) during the severe drought affecting Tunisian arid areas in 2002, a range of physiological parameters were investigated in three adjacent orchards. Two olive orchards were rain-fed, one located on a sandy soil, and the other on a sandy-loam clay soil. A third orchard was also located on sandy soil, but received remedial irrigation (415 mm of water per year; ~40% of olive evapotranspiration). Predawn leaf water potential (Ψpd) did not fall below –1.52 MPa for irrigated olive trees. However, a large decrease in Ψpd was observed for rain-fed olive trees in the same period with Ψpd measured at about –3.2 MPa on sandy soil and –3.6 MPa on sandy-loam clay soil. At the same time, the minimal leaf water potential recorded at midday (Ψmin) decreased to –4.15 MPa and –4.71 MPa in the rain-fed trees for sandy and sandy-loam clay soil, respectively. For irrigated trees, the Ψmin was –1.95 MPa. These results were associated with relative water content, which varied from 80% for irrigated trees to 54 and 43.6%, respectively, for rain-fed trees and trees subjected to severe drought. In August, when the relative water content values were less than 50%, a progressive desiccation in the outer layer of canopy and death of terminal shoots were observed in trees, which grew on the sandy-loam clay soil. Furthermore, low soil water availability also affected (negatively) the net photosynthetic rate in rain-fed orchards (10.3 µmol/m2.s for irrigated trees v. 5.3 µmol/m2.s in rain-fed trees on sandy soil) and stomatal conductance (98.5 mmol/m2.s v. 69.3 mmol/m2.s). However, it improved water use efficiency (7.6 v. 4.7 µmol CO2/mmol H2O), which increased by more than 50% in both groups of rain-fed trees compared with the irrigated ones. We can conclude that olive trees respond to drought by showing significant changes in their physiological and biological mechanisms. These results also help our understanding of how olive trees cope with water stress in the field and how marginal soils can restrict growth and lower yields.

EFFET DE LA FERTILISATION AZOTEE SUR LE DEVELOPPEMENT DE LA RHYNCHOSPORIOSE DE L’ORGE

1986 ◽  
Vol 66 (3) ◽  
pp. 795-799 ◽  
Author(s):  
LUC COUTURE ◽  
DANIEL ISFAN
Keyword(s):  
Hordeum Vulgare ◽  
Disease Severity ◽  
Clay Soil ◽  
Sandy Loam ◽  
Spring Barley ◽  
Nitrogen Fertilizers ◽  
Absolute Level ◽  
Set Up ◽  
Fertilisation Azotée ◽  
Different Soils

The effect of nitrogen fertilizers applied as urea or ammonium nitrate at doses of 0, 40, 80, 120, and 160 kg ha−1 on scald in spring barley (Hordeum vulgare) grown on two different soils was examined during 2 yr. A strong significant positive correlation was found between nitrogen dose and severity of scald during the 2 yr. Nitrogen influenced disease severity the same way in both soils although the absolute level of disease was higher in plots set up in sandy loam than in clay soil. Disease severity was approximately the same in barley fertilized with urea or ammonium nitrate.Key words: Nitrogen fertilizer, nitrogen form, barley, Hordeum vulgare, scald, Rhynchosporium secalis

Factors Affecting Johnsongrass Rhizome Production and Germination

Weed Science ◽  
1972 ◽  
Vol 20 (1) ◽  
pp. 41-45 ◽  
Author(s):  
C. G. McWhorter
Keyword(s):  
Soil Profile ◽  
Clay Soil ◽  
Sandy Loam ◽  
Sorghum Halepense ◽  
Percentage Germination ◽  
Factors Affecting ◽  
Opposite Trend ◽  
Rhizome Buds

Approximately 80% of the johnsongrass(Sorghum halepense(L.) Pers.) rhizomes produced in clay soil were in the top 7.5 cm, but 80% of the rhizomes in sandy loam occurred in the top 12.5 cm. Distribution of rhizomes within the top 20 cm of soil was more uniform in sandy loam than in clay; yet, 5% of the rhizomes produced in clay occurred deeper than 20 cm, but only 1% of the rhizomes in sandy loam occurred deeper than 20 cm. Incorporation ofa,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-/7-toluidine (trifluralin) in soil at 0.84 kg/ha reduced rhizome production approximately 50% throughout the soil profile but reduced rhizome production most in the top 6 cm. More plants emerged from rhizomes when planted in sandy loam than in clay. More plants emerged from short rhizomes (76 mm) than from long rhizomes (152 mm) when planted at depths to 7.6 cm, but the opposite trend was obtained when rhizomes were planted deeper. Percentage germination of rhizome buds increased as rhizomes were cut into smaller pieces. Exposure of rhizomes to temperatures of 50 to 60 C killed buds within 1 to 3 days. Rhizomes usually survived temperatures of −3 to −5 C for only a few hours.

Contributions of pressure and flow sensitivity to autoregulation in mesenteric arterioles

1976 ◽  
Vol 231 (6) ◽  
pp. 1686-1698 ◽  
Author(s):  
PC Johnson ◽  
M Intaglietta
Keyword(s):  
Arterial Pressure ◽  
Static Pressure ◽  
Volume Flow ◽  
Relative Influence ◽  
Pressure Reduction ◽  
Flow Sensitivity ◽  
Stepwise Reduction ◽  
Fourth Series ◽  
Series Of Experiments ◽  
Intravascular Pressure

The relative influence of presence and flow on dilation of arterioles with pressure reduction was examined in preparations of cat mesentery. Erythrocyte velocity and diameter were measured in individual arterioles during stepwise reduction in mesenteric arterial pressure. Volume flow was calculated from velocity and diameter data. Approximately half of the arterioles which dilated with pressure reduction also showed an increase in volume flow. In a second series of experiments, a graded reduction of flow in single arterioles was produced by local downstream occlusion. Graded occlusion caused dilation. In a third series, flow in single arterioles was completely stopped by downstream occlusion, and arterial pressure was then lowered. Most arterioles dilated with pressure reduction. In a fourth series, flow in the total preparation was completely stopped and static intravascular pressure set by a reservoir. Elevation of static pressure typically produced arteriolar constriction. We conclude from these studies that the mesenteric arteriole is sensitive both to intravascular pressure and flow, with the former probably more important than the latter in the phenomenon of autoregulation.

Turbine Blade Life Prediction Using Fluid-Thermal-Structural Interaction Simulation

2016 ◽  
Author(s):  
I. A. Ubulom ◽  
A. Fien ◽  
A. J. Neely ◽  
K. Shankar
Keyword(s):  
Fatigue Life ◽  
Hysteresis Loop ◽  
Turbine Blade ◽  
Stable Condition ◽  
Cyclic Stress ◽  
Aerodynamic Load ◽  
Temperature Dependent ◽  
Strain Behavior ◽  
Softening Behavior ◽  
Interaction Simulation

In this study a fluid-thermal-structural simulation is performed to investigate cyclic stress-strain behavior and fatigue life of a gas turbine blade. The Hysteresis loop characteristic of the blade is presented under the coupled influence of various loading conditions, aerodynamic, thermal and static centrifugal loadings. Based on the predicted loading behavior, an energy-based method was used to analyze the fatigue and cumulative damage properties of the blade. The predicted hysteresis loop under aerodynamic load was purely of elastic nature and as such tends to assume a Masing behavior at the stable condition. The case for a combined thermal and aeromechanical loading showed a non-Masing behavior, but rather a temperature-dependent material softening behavior. The fatigue life was also estimated based on the energy density approach using the predicted thermal-structural predicted cyclic loops.

Effects of some soil conditions on sugar-beet seedling emergence

1972 ◽  
Vol 79 (3) ◽  
pp. 543-545 ◽  
Author(s):  
P. C. Longden
Keyword(s):  
Soil Moisture ◽  
Sugar Beet ◽  
Clay Soil ◽  
Sandy Loam ◽  
Seedling Emergence ◽  
Clay Soils ◽  
Soil Types ◽  
Soil Conditions ◽  
Soil Conditioners ◽  
Water Holding

SUMMARYSeven soil conditioners added to a sandy clay soil at Saxmundham did not benefit sugar-beet seedling emergence in four experiments in 3 years. In microplots at Broom's Barn free draining peat and sandy loam gave consistently more seedlings than limestone loam or flinty loam. In the laboratory, for each of three soil types, emergence was maximal only for a small soil moisture range and decreased rapidly when soils became drier or wetter. This suggests that conditioners which increase water-holding capacity should be tested on sandy loams rather than clay soils and that seed-bed preparation on heavier soils should seek to aerate the soil.

scholarly journals Mineralization of pig slurry compost treated with retorted oil shale and dicyandiamide in two contrasting soils

2021 ◽  
Vol 56 ◽  
Author(s):  
Luanna Corrêa Monteiro ◽  
Celso Aita ◽  
Janquieli Schirmann ◽  
Stefen Barbosa Pujo ◽  
Diego Antônio Giacomini ◽  
...  
Keyword(s):  
Oil Shale ◽  
Clay Soil ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
N Immobilization ◽  
Pig Slurry ◽  
Mineral N ◽  
Total N ◽  
Loam Soil ◽  
C And N

Abstract: The objective of this work was to evaluate carbon and nitrogen mineralization in the soil after the application of composts produced in an automated composting plant, using pig slurry (PS) with and without the addition of retorted oil shale (ROS) and dicyandiamide (DCD) during composting. Laboratory studies were carried out for 180 days on two soils with contrasting characteristics: sandy-loam Typic Paludalf and clay Rhodic Hapludox, which were managed for more than 10 years under a no-tillage system. The composts were thoroughly mixed with the soils. The mineralization of the C and N from the compost was evaluated by measuring continuously CO2 emissions and periodically mineral N (NH4+ + NO3-) content in the soils, respectively. The mineralization of the C from the compost without ROS and DCD was higher in the sandy-loam soil (20.5%) than in the clay soil (13.9%). Similarly, 19.4% of the total N from the compost was mineralized in the sandy-loam soil and 10.9% in the clay soil. The presence of ROS in the compost reduced C mineralization by 54%, compared with the treatment without additives, in the sandy-loam soil and caused net N immobilization in both soils during incubation. The addition of DCD during PS composting did not affect the mineralization of the C and N from the compost in both soils. The addition of ROS during the composting of PS favors the retention of the C from the compost in the soil, especially in the sandy-loam one, but results in a net N immobilization.

scholarly journals Pretreatment of soil samples before NO3-N analysis.

1981 ◽  
Vol 29 (1) ◽  
pp. 15-22
Author(s):  
T. Breimer ◽  
J.H.G. Slangen
Keyword(s):  
Room Temperature ◽  
Clay Soil ◽  
Sandy Loam ◽  
Organic Soil ◽  
Soil Samples ◽  
Clay Soils ◽  
Room Temperature Storage ◽  
N Level ◽  
Temperature Storage ◽  
Long Storage

Storage of sandy, loam and clay soil samples at 35 deg C or 70 deg C for 2-3 days reduced the NO3-N level in the soils. Freezing (-20 deg C), refrigeration (-4 deg C) or storage at room temperature for 2-3 days had little effect on NO3-N levels, although low or room temperature storage for 2 months increased NO3-N levels in the loam and clay soils. Freezing or refrigeration of the sandy soil for 2 months reduced NO3-N levels, while long storage at room temperature markedly increased NO3-N levels in this highly organic soil. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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