scholarly journals Analysis on water migration in freeze-thaw process of composite lining canal in seasonal frozen soil area

2021 ◽  
Vol 71 (1&2) ◽  
pp. 25
Author(s):  
Jiang Haibo ◽  
Jin Jin ◽  
Qin Zhipeng
Keyword(s):  
Water Content ◽  
Water Transfer ◽  
Soil Samples ◽  
Initial Water ◽  
Foundation Soil ◽  
Freeze Thaw ◽  
Freezing Period ◽  
Maximum Water ◽  
Composite Lining ◽  
Water Contents

In order to quantify the migration rule of water in composite lining canal foundation soil during the freeze-thaw process, the outdoor prototype test is performed to prove the change rules of water in different positions and depths of the rigidflexible mixed composite lining canal foundation during the whole freeze-thaw cycle. The prototype observation test shows that during the freezing period, the water content within the 0~80cm depth of the canal foundation soil increases with the depth, and that within the depth of 80~160cm decreases gradually with the depth. In the freezing period, water accumulates in the depth of 60 ~ 80cm, with a maximum water transfer amount of +13.2%, which occurs at the canal bottom. In the thawing period, the maximum water content also occurs at the canal bottom, with a maximum water transfer amount of -11.0%. Through the laboratory test of soil samples, the water migration development and change rules of the canal foundation soil, under different moisture contents and temperature gradients are studied in unilateral pattern. In the case of the same top plate control temperature, soil samples with similar initial water contents have similar water transfer amounts. The samples with higher initial water content have higher water transfer amount, with higher water accumulation, normally accumulating in the depth of 16~18cm. The results indicate that high water contents make it easy to gather water in soil samples during the freezing period.

Compression properties of pile fabrics in the presence of water

2020 ◽  
Vol 90 (15-16) ◽  
pp. 1704-1712
Author(s):  
Yuriko Kibayashi ◽  
Hiroko Yokura ◽  
Sachiko Sukigara
Keyword(s):  
Water Absorption ◽  
Water Content ◽  
Water Transfer ◽  
Weft Yarn ◽  
Compression Properties ◽  
Maximum Water ◽  
Water Contents

The compression properties of towel pile fabrics with water contents from 0% to 500% were measured to investigate the effect of pile ratio and weft yarn density. The compression energy decreased substantially from 0% to 50% and 100%, and then increased with the water content. Towel fabric with a high pile ratio showed a larger increase in compression energy than towel fabric with a low pile ratio. Water transfer through the towels was investigated in both horizontal and vertical directions. The vertical water transfer from the pile surface to the base was related to the maximum water absorption velocity ( Vmax). Subjectively evaluated, soft towels showed larger Vmax and compression energy values with water than short-pile towels.

Experimental Study on Moisture Migration in Unsaturated Loess under Freezing Effect

2012 ◽  
Vol 204-208 ◽  
pp. 552-556 ◽  
Author(s):  
Tie Hang Wang ◽  
Hui Zhang ◽  
Xing She Lu
Keyword(s):  
Water Content ◽  
Negative Temperature ◽  
Soil Samples ◽  
Initial Water Content ◽  
Freezing Front ◽  
Initial Water ◽  
Moisture Migration ◽  
Maximum Water ◽  
Unsaturated Loess ◽  
Maximum Water Content

Test equipments were designed and manufactured for producing moisture migration in unsaturated loess under freezing effect. The results showed that both the amount of freezing-thawing cycles and initial water content of soil samples affect the process of moisture migration. As the freezing front advanced in the sample, the water content in the unfrozen part significantly reduced and the water content in the freezing part significantly increased, with the maximum water content at the freezing front. Comparing to the moisture migration in the unfrozen part, the moisture migration to the freezing front in the freezing part was relatively slow. For soil samples with higher initial water content, the increment of water content at the freezing front was higher and sometimes ice could be formed. During a certain amount of freezing-thawing cycles, the water content at the freezing front kept increasing. However, as the amount of freezing-thawing cycles continued increasing, the freezing front started to move to the part with negative temperature and the maximum water content appears at the end with the lowest temperature.

Effects of differential drying rates on viability retention of recalcitrant seeds of Ekebergia capensis

1998 ◽  
Vol 8 (4) ◽  
pp. 463-471 ◽  
Author(s):  
N. W. Pammenter ◽  
Valerie Greggains ◽  
J. I. Kioko ◽  
J. Wesley-Smith ◽  
Patricia Berjak ◽  
...  
Keyword(s):  
Water Content ◽  
Exponential Function ◽  
Time Course ◽  
Drying Rate ◽  
Recalcitrant Seeds ◽  
Tissue Water ◽  
Initial Water ◽  
Viability Loss ◽  
Drying Rates ◽  
Water Contents

AbstractThe drying rate of whole seeds of Ekebergia capensis (Meliaceae) was shown to influence the response to desiccation, with rapidly dried seeds surviving to lower water contents. Short-term rapid drying (to water contents higher than those leading to viability loss) actually increased the rate of germination. The form of the time course of decline of axis water content varied with drying rate; slow drying could be described by an exponential function, whereas with rapid drying initial water loss was faster than predicted by an exponential function. These observations suggest that slow drying brought about homogeneous dehydration and that the rapid drying was uneven across the tissue. This raised the possibility that the different responses to dehydration were a function of different distributions of water in the axis tissue under the two drying regimes. However, ultrastructural observations indicated that different deleterious processes may be occurring under the different drying treatments. It was tentatively concluded that a major cause of viability loss in slowly dried material was likely to be a consequence of aqueous-based processes leading to considerable membrane degradation. Uneven distribution of tissue water could not be rejected as a contributory cause of the survival of rapidly dried seeds to low bulk water contents. The differential response to dehydration at different drying rates implies that it is not possible to determine a ‘critical water content’ for viability loss by recalcitrant seeds.

scholarly journals An empirical model for describing the influence of water content and concentration of sulfamethoxazole (antibiotic) in soil on the total net CO2 efflux

2020 ◽  
Vol 68 (4) ◽  
pp. 351-358
Author(s):  
Miroslav Fér ◽  
Radka Kodešová ◽  
Barbora Kalkušová ◽  
Aleš Klement ◽  
Antonín Nikodem
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Solution Treatment ◽  
Soil Microbial Activity ◽  
Soil Samples ◽  
Co2 Efflux ◽  
The Impact ◽  
Water Contents ◽  
Soil Water Contents

AbstractThe aim of the study was to describe the impact of the soil water content and sulfamethoxazole, SUL, (antibiotic) concentration in soil on the net CO2 efflux. Soil samples were taken from topsoils of a Haplic Fluvisol and Haplic Chernozem. Soil samples were packed into the steel cylinders. The net CO2 efflux was measured from these soil columns after application of fresh water or SUL solution at different soil water contents. The experiments were carried out in dark at 20°C. The trends in the net CO2 efflux varied for different treatments. While initially high values for water treatment exponentially decreased in time, values for solution treatment increased during the first 250–650 minutes and then decreased. The total net CO2 effluxes measured for 20 hours related to the soil water content followed the second order polynomial functions. The maximal values were measured for the soil water content of 0.15 cm3 cm−3 (Haplic Fluvisol with water or solution, Haplic Chernozem with solution) and 0.11 cm3 cm−3 (Haplic Chernozem with water). The ratios between values measured for solution and water at the same soil water contents exponentially increased with increasing SUL concentration in soils. This proved the increasing stimulative influence of SUL on soil microbial activity.

The Influence of Dehumidifying Condition on Expansive Soil Engineering Properties

2012 ◽  
Vol 594-597 ◽  
pp. 487-492
Author(s):  
Xiong Wei Li ◽  
Ai Jun Wang ◽  
Guo Zhong Dai
Keyword(s):  
Shear Strength ◽  
Relative Humidity ◽  
Water Content ◽  
Expansive Soil ◽  
Expansion Ratio ◽  
Soil Samples ◽  
Engineering Properties ◽  
Drying Rate ◽  
Initial Water Content ◽  
Initial Water

The expansive soil behaviour of expansive deformation and shear strength is deeply influenced by humidity condition. Different soil drying rate was set with constant temperature and different relative humidity. When saturated soil samples was dried to the different predetermined water content, the expansion ratio test with the upper load was made. It is shown that in the condition of high relative humidity, the expansion ratio is high. The smaller initial water content and upper load may lead to a larger swelling deformation. When soil samples with different initial water content was fully expanded, the consolidated direct shear tests were made. It is shown that the smaller drying rate leads to the greater shear strength after full expansion. What’s more, the upper load may improve the soil shear strength.

Experimental Study on Dewatering Dredged Clay with Ventilating Vacuum Method

2011 ◽  
Vol 261-263 ◽  
pp. 1650-1654 ◽  
Author(s):  
Feng Ji ◽  
Jian Wen Ding ◽  
Zhen Shun Hong ◽  
Yue Gui
Keyword(s):  
Experimental Study ◽  
Spatial Distribution ◽  
Surface Water ◽  
Water Content ◽  
Liquid Limit ◽  
Initial Water Content ◽  
Distribution Law ◽  
Initial Water ◽  
Vacuum Method ◽  
Water Contents

A series of model tests were performed on dredged clay with high initial water contents for investigating the dewatering behavior by ventilating vacuum method (VVM). The results shows that the surface water separated from dredged clay can be quickly removed by VVM in which a new pattern PVD is used. In addition, the method also speeds up the deposition of dredged clay. The volume of dredged clay with an initial water content of 4.5 times liquid limit decreases by 50 percent within two months. This paper also investigated the spatial distribution law of water content by TDR method. It is found that the drainage distance of PVD is about 0.3-0.4m.

Detecting Soil Water Content of Red Soil and Younger Alluvial Soil Using a Spectrometer

2013 ◽  
Vol 284-287 ◽  
pp. 287-290
Author(s):  
Jie Lun Chiang ◽  
Shih Hao Jien
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Estimation Error ◽  
Alluvial Soil ◽  
Soil Samples ◽  
Red Soil ◽  
Estimation Accuracy ◽  
Full Development ◽  
Water Contents

To provide a simple and fast alternative in measuring soil water content (SWC), a spectrometer was used to detect SWC because of different soil water contents, leading to different reflectance spectrums. Two commonly seen soil types in Taiwan are red soil and younger alluvial soil, which were used as test materials in this study. Fifty red soil samples and 50 younger alluvial soil samples were used as testing samples for comparative study. The root mean square error of SWC estimation of red soil and younger alluvial soil is 3.65 and 7.26, respectively. The results show that the estimation accuracy of red soil is higher than that of younger alluvial soil. The estimation error is random for red soil, and decreases exponentially for younger alluvial soil. Spectrometers have the potential to detect soil water content, especially in red soil. After full development of this technology, remote sensing will be applied to detect soil water content or even water-induced landslides.

Prediction of evaporation with the CONSEVB simulation-model - an experimental evaluation

Soil Research ◽  
1994 ◽  
Vol 32 (1) ◽  
pp. 45
Author(s):  
HP Cresswell ◽  
DJ Painter ◽  
KC Cameron
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Simulation Model ◽  
Water Content ◽  
Soil Water ◽  
Cost Benefit ◽  
Initial Water ◽  
Input Parameters ◽  
Moisture Characteristic ◽  
Water Contents

The CONSERVB simulation model was evaluated by comparing predictions of evaporation, net radiation, and water and temperature profiles with measured values from a bare, tilled soil in New Zealand conditions. No model calibration was used whatsoever. The assessment included tests of the sensitivity of output to variations (uncertainty) in input parameters. On 18 of the 24 days simulated, evaporation was within 0.5 mm day-1 of the measured means, although that represented less than 20% error on only 6 days. The mean difference between measured and simulated surface soil temperature for the two drying cycles was 1.2 and 1.3�C; most of this error occurred in warm conditions around noon each day. Simulated soil temperature at 0.05 m exceeded measured values during the warmest parts of the day and fell below them at night. Soil temperature prediction was sensitive to the air temperature and solar radiation climatic inputs. Evaporation prediction was sensitive to initial profile water contents, to the soil moisture characteristic and to the unsaturated hydraulic conductivity inputs. An increase in the water content at each matric potential step in the soil moisture characteristic input by a factor of 1.10 resulted in an increase in simulated cumulative evaporation of over 40%. For the prediction of evaporation and soil water content, field effort in the measurement of the soil hydraulic properties and initial water contents (where simulations are short) for model parameterization is likely to give the highest cost-benefit. Very accurate determinations of these input parameters and functions are required for model evaluation. Given the sensitivities, and the uncertainties associated with measurement and prediction of model input parameters, the predictions from CONSERVB have large uncertainties associated with them. Field-measured values of cumulative evaporation were within the range of variation in predicted values that resulted from uncertainty in determination of initial soil water contents alone. CONSERVB is more applicable to an operations research modelling approach than to prediction of evaporation and surface water contents in specific conditions.

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