NUMERICAL INVESTIGATION OF PERFORMANCE OF CAPILLARY BARRIER SYSTEM WITH TRANSPORT LAYER

2015 ◽  
Vol 77 (12) ◽  
Author(s):  
Gambo Haruna Yunusa ◽  
Azman Kassim ◽  
Zaihasra Abu Talib ◽  
Shabena Jasmin Mohamed Yoosoof
Keyword(s):  
Soil Layer ◽  
Climatic Conditions ◽  
Rainfall Infiltration ◽  
Transport Layer ◽  
Alternative Measure ◽  
Residual Soil ◽  
Capillary Barrier ◽  
Seepage Analysis ◽  
Promising Alternative ◽  
Rainfall Condition

A capillary barrier system is a promising alternative measure for controlling rainfall infiltration into unsaturated residual soil slopes. Although, system with capillary barrier effect has been successfully applied to avert rainfall infiltration in dry and semi-dry climates, its application in humid climates with high precipitation rate is still unsatisfactory. Therefore, this paper evaluates the performance of a modified capillary barrier system with transport layer under humid climatic conditions. The capillary barrier system and the transport layer were simulated with Grade V and Grade VI soils and gravel, respectively. The system was subjected to various rainfall intensities using saturated/unsaturated seepage analysis. When the initial suction of 32 kPa was assigned to the system and subjected to the worst rainfall condition for 24-hour duration, the breakthrough time increases with increase in the thickness of grade VI residual soil layer in the conventional capillary barrier system and the maximum diversion length achieved is less than 2 m. However, when a transport layer was placed at the interface of the grade V and grade VI soils, the diversion length increases to 15 m and avert breakthrough occurrence under the same condition. Therefore, the inclusion of transport layer in a residual soil capillary barrier system improved its performance and prevent breakthrough occurrence.

Influence of transport Layer on Transient Suction Distribution in a Two-Layered Slope

2015 ◽  
Vol 72 (3) ◽  
Author(s):  
Gambo Haruna Yunusa ◽  
Azman Kassim ◽  
Ahmad Safuan A. Rashid
Keyword(s):  
Material Properties ◽  
Slope Failure ◽  
Matric Suction ◽  
Rainfall Infiltration ◽  
Transport Layer ◽  
Residual Soil ◽  
Soil Slope ◽  
Capillary Barrier ◽  
Layered Slope ◽  
Residual Soil Slope

Residual soil slope failure due to rainfall infiltration is one of geotechnical hazards receiving much attention in many tropical climate countries. The infiltrating water eliminates matric suction in the residual soil slope and results in slope failure. A capillary barrier is used to prevent excessive rainfall infiltration and preserve matric suction in the residual soil slope and hence prevent rainfall-induced slope failure. A numerical study to examine the performance of a transport layer in a two-layered slope using capillary barrier principle was presented in this paper. Material properties of tropical residual soils consisting of Grade V (silty gravel) and Grade VI (sandy silt) were used and modelled a two-layered slope. These material properties were obtained from representative soil sample of Balai Cerapan slope in Universiti Teknologi Malaysia, Johor Bahru campus. A granite chips (Gravel) was also incorporated to act as a transport layer in the numerical model. The simulated slope model was then subjected to three different rainfall intensities of 9 mm/h (rainfall 1), 22 mm/h (rainfall 2) and 36 mm/h (Rainfall 3) representing short, medium and high intensity rainfalls, respectively. A total of six numerical schemes were performed by restricting the thickness of the transport layer to 0.1 m. However, to assess the effect of the transport layer thickness on suction distribution; the thickness was increased to 0.2 m. The results of the study show that inclusion of gravelly transport layer enables the top layer of fine sandy silt residual soil to retain the infiltrating water as a result of capillary break developed at the interface and also divert it above the interface towards the direction of the toe of the slope. Similarly the transport layer is found to be effective in preventing water breakthrough occurrence into the underlying coarser soil layer of the two-layered slope, especially when the thickness of the transport layer is optimum.

LABORATORY INVESTIGATION OF DRAINAGE CELL AS TRANSPORT LAYER IN RESIDUAL SOILS

2016 ◽  
Vol 78 (6-12) ◽  
Author(s):  
Gambo Haruna Yunusa ◽  
Azman Kassim
Keyword(s):  
Water Content ◽  
Slope Failure ◽  
Soil Layer ◽  
Transport Layer ◽  
Alternative Measure ◽  
Lower Grade ◽  
Residual Water ◽  
Capillary Barrier ◽  
Cell Transport ◽  
Set Up

Transport layer or unsaturated drainage layer is an alternative measure often employed to improve the performance of a capillary barrier system. A capillary barrier is an earthen cover used to prevent rainfall-induced slope failure. In this study, potential of using drainage cell system as transport layer is exploited using laboratory experimental methods. The drainage cell was sandwiched between grade V and grade VI soils in a two-dimensional laboratory slope model to act as transport layer. Coarse particles of gravel were compacted within the drainage cell to facilitate capillary break development at the interface. Each of grade V and grade VI soil was mixed with water content identical to residual water content determined from the soil water characteristic curves (SWCC) of each soil to enable simulation of their initial condition.  Both soils are then compacted in the slope model to their dry densities. The whole set up was subjected to three rainfall intensities of 1.0586 x 10-5 m/s, 1.2014 x 10-6 m/s and 3.7337 x 10-7 m/s for 2 hour, 24 hour and 7 day, respectively. These rainfall intensities were determined from Intensity-Duration-Frequency (IDF) curve and were applied through a rainfall simulator which is part of the laboratory set up. The results shows that the transport layer formed with drainage cell was capable of producing capillary break and impedes percolation of the infiltrating water into the lower grade V soil layer. The accumulated water was later drained laterally above the interface of grade VI soil and drainage cell transport layer towards the toe of the slope model. In an event that the infiltrating water percolates the drainage cell transport layer due to longer rainfall duration, the drainage cell provides a definite direction through which the infiltrating water flow and diverted laterally. It was found that the modified capillary barrier with drainage cell transport layer performed much better than the conventional capillary barrier system.

Selection of drought-resistant crops for South Steppe of Ukraine

2021 ◽  
Vol 5 (1) ◽  
pp. 13-22
Author(s):  
V. V. Gamayunova ◽  
L. H. Khonenko ◽  
M. I. Fedorchuk ◽  
O. A. Kovalenko
Keyword(s):  
Humus Content ◽  
Soil Layer ◽  
Weather Conditions ◽  
Growing Season ◽  
Grain Sorghum ◽  
Climatic Conditions ◽  
Mineral Fertilizers ◽  
Chemical Application ◽  
Sowing Dates ◽  
Drought Resistant

The cultivation expediency of more drought-resistant crops, in particular sorghum, millet, false flax, safflower and others, instead of sunflower in the area of the Southern Steppe of Ukraine is substantiated. This is, first of all, required by climate change both in Ukraine and in the world. Since 2004, researches of field crops were carried out in the conditions of the Educational and Scientific Practical Center of the Mykolaiv National Agrarian University. Soil phase is the southern chernozem with humus content in the 0–30 cm soil layer which consist of 2.96–3.21 %, with medium and high level of availability of mobile phosphorus and potassium and low – mobile nitrogen. Experiments with soriz (Oksamyt hybrid) were conducted during 2004–2006, millet (Tavriiske, Kostantynivske, Skhidnevarieties) in 2008–2010, grain sorghum (Stepovyi 5 hybrid) in 2014–2016, safflower dye (Lahidnyi variety) in 2017–2019. The years of research differed significantly in temperature and even more in the amount of precipitation before sowing and during the growing season of crops. However, the weather conditions were typical of the Southern Steppe zone of Ukraine. It is established that all studied drought-resistant crops respond positively to nutrition optimization – the level of yield and quality of grain or seeds increases. It was found that the soriz productivity depending on the application of fertilizers and sowing dates increased by 37.6–39.2 %, millet –by 33.3–41.6 %, grain sorghum depending on the background of nutrition and growing conditions – by 8.2–33.2 %, dye safflower – by 11.1–64.6 %. It was determined that the optimization of nutrition of cultivated crops allows to increase their resistance to adverse conditions and productivity in the case of application of low doses of the mineral fertilizers before sowing, pre-sowing treatment of seeds, and growth-regulating chemical application of plants on the main stages of the growing season. Key words: drought-resistant plants, climatic conditions, nutrition optimization, yield, crop quality, varieties, sowing dates.

scholarly journals Experimental Study of Rainfall Infiltration in an Analog Fracture-matrix System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhen Zhong ◽  
Huicai Gao ◽  
Yunjin Hu
Keyword(s):  
Unsaturated Flow ◽  
Rainfall Infiltration ◽  
Combination Method ◽  
Matrix System ◽  
Capillary Barrier ◽  
Hydraulic Behaviour ◽  
Experimental Apparatus ◽  
Matrix Interactions ◽  
The Matrix ◽  
Flow Through

In this study, an experimental apparatus was developed to investigate unsaturated infiltration in an analog fracture-matrix system. Fracture and adjacent matrix is simulated by sands with various particle sizes. Four rainfall infiltration experiments were performed on the analog fracture-matrix system at a constant rainfall rate of 100 mm/h. The process of rainfall infiltration is measured by a combination method of tensiometers and quick moisture apparatus. The measured results reveal that fracture-matrix interactions certainly exert influences on the hydraulic behaviour of unsaturated fractured matrix, and the fluid flow mainly infiltrates along the nonuniform paths within the matrix. Moreover, it is observed that the influences are greater when using a coarser sand to mimic the fracture. Specifically, the wetting phase in the matrix moves faster than that in the fracture; the fracture, therefore, acts as a vertical capillary barrier, but there exists lateral water exchange from the matrix to the fracture. Overall, this study has demonstrated the importance of fracture/matrix interactions, which should be considered when dealing with unsaturated flow through permeable matrices.

scholarly journals Evaluation method of diversion length of capillary barrier composing of 3 layers ground in considering the thickness of the upper soil layer

2016 ◽  
Vol 11 (4) ◽  
pp. 305-313
Author(s):  
Kazunobu MATSUMOTO ◽  
Kaoru KOBAYASHI ◽  
Toshihiro MORII ◽  
Satoru NAKAFUSA
Keyword(s):  
Evaluation Method ◽  
Soil Layer ◽  
Capillary Barrier

scholarly journals Hole Transport Behaviour of Various Polymers and Their Application to Perovskite-Sensitized Solid-State Solar Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Jeongmin Lim ◽  
Seong Young Kong ◽  
Yong Ju Yun
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Solid State ◽  
Perovskite Solar Cell ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Good Efficiency ◽  
Promising Alternative ◽  
Transport Behaviour

Inorganic-organic mesoscopic solar cells become a promising alternative for conventional solar cells. We describe a CH3NH3PbI3 perovskite-sensitized solid-state solar cells with the use of different polymer hole transport materials such as 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-OMeTAD), poly(3-hexylthiophene-2,5-diyl) (P3HT), and poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7). The device with a spiro-OMeTAD-based hole transport layer showed the highest efficiency of 6.9%. Interestingly, the PTB7 polymer, which is considered an electron donor material, showed dominant hole transport behaviors in the perovskite solar cell. A 200 nm thin layer of PTB7 showed comparatively good efficiency (5.5%) value to the conventional spiro-OMeTAD-based device.

Sugarbeet (Beta vulgaris) response to residual soil N under Mediterranean agronomic practices

1999 ◽  
Vol 132 (3) ◽  
pp. 273-280 ◽  
Author(s):  
P. MARTÍN-OLMEDO ◽  
J. M. MURILLO ◽  
F. CABRERA ◽  
R. LÓPEZ
Keyword(s):  
Beta Vulgaris ◽  
Time Course ◽  
Sugar Content ◽  
N Uptake ◽  
Soil Layer ◽  
Wastewater Sludge ◽  
Control Treatment ◽  
Residual Soil ◽  
Juice Quality ◽  
Mineral Fertilization

Autumn-sown sugarbeet (Beta vulgaris L.) responses (sugar yield, plant N-uptake and juice quality) were studied in relation to the residual NO3−-N in a soil of southwestern Spain which, for the previous five years (1989–93), had received high N rates, in accordance with conventional fertilization schedules used by farmers in the area. Three different combinations of fertilizers, supplying equal amounts of N, were used during the fertilization period (1989–93): a mineral fertilization treatment (MF, a complex 15N-15P2O5-15K2O) and two organo-mineral fertilization treatments (an olive mill wastewater sludge compost, AC, and a depotassified concentrated beet vinasse, V). All these treatments also received a top-dressing with urea (46% N). A control treatment (C), without fertilization was included for comparison.During the major part of the beet growing season, the presence of almost four times as much mineral N in the 0·100 cm soil layer of previously fertilized plots (AC, V and MF) than in the unfertilized one (C), led to a significant increase (P<0·05) in total fresh weight yield and N-uptake, but also to a significant decrease (P<0·05) in sugar content and beet processing quality. The time course of NO3−-N concentration in sugarbeet petioles and the evolution of the nutritional state of leaf-blades gave advance information about the final response of the crop to the different fertilization treatments. Besides N, Na was the element which, due to the repeated and high fertilization rates applied, had a major effect in reducing the technological quality of the sugarbeet.

scholarly journals Simulation Parameter Selection and Steady Seepage Analysis of Binary Structure Slope

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2747
Author(s):  
Xuhe Gao ◽  
Baocheng Cheng ◽  
Weiping Tian ◽  
Zhipei Zhang ◽  
Jiachun Li ◽  
...  
Keyword(s):  
Steady State ◽  
Safety Factor ◽  
Water Pressure ◽  
Soil Layer ◽  
Equivalent Strain ◽  
Extreme Value ◽  
Test Method ◽  
Seepage Analysis ◽  
Binary Structure ◽  
Slope Excavation

The selection of calculation parameters for slope excavation support design and the analysis of seepage stability is a significant challenge. This difficulty also hinders the development of slope support engineering. This study examined the right binary structure slope engineering of the K5 + 220–K5 + 770 section of the TJ1A mark of the Jiangkou-Weng’an Highway in Guizhou province. In this study, we propose and use the deep displacement monitoring data and p value test method to check the simulation parameters. Furthermore, the superposition calculation method for steady-state seepage analysis of slope geotechnical structure is proposed. A comparative analysis of the displacement, strain, stress, and safety factor of the slope after the application of pore water pressure was carried out for three slope conditions. The analysis showed that steady-state seepage has a significant effect on the displacement of the slope during the completion of excavation. As a result, a continuous distribution of strain arises on the slope along the interface between the potential sliding surface and the rock–soil layer, and then forms a continuous sliding zone. Additionally, steady-state seepage has a significant effect on the position of the displacement distribution during the initial support of the slope, leading to a significant increase in the extreme value of the shear outlet displacement of the potential slip surface of the slope and in the extreme value of equivalent strain. Finally, steady-state seepage reduces the displacement and equivalent strain upon construction of the secondary slope support. The steady-state seepage has a limited effect on the stress concentration, but reduces the safety factor calculated using the strength reduction method, in all three stages of slope excavation and support. This study enriches the analysis methods for determining the stability of a dual-structure slope during the rainy season, and provides new ideas for the safety and control of slope support projects.

scholarly journals Seepage Analysis on the Surface Layer of Multistage Filled Slope with Rainfall Infiltration

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Bingxiang Yuan ◽  
Zengrui Cai ◽  
Mengmeng Lu ◽  
Jianbing Lv ◽  
Zhilei Su ◽  
...  
Keyword(s):  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rainfall Infiltration ◽  
Feature Points ◽  
Saturation State ◽  
Seepage Analysis ◽  
Safety Coefficient ◽  
Infiltration Model ◽  
Saturation Region

Based on the theory of rainfall infiltration, the surface infiltration model of multilevel filled slope was established by using the SEEP/W module of GeoStudio. The changes of the volumetric water content (VWC) and pore water pressure (PWP) in the surface of the slope during the rainfall infiltration were analyzed, and the influence of the change of the rainfall conditions on the VWC and PWP was considered. The analysis showed that VWC and PWP increased when the rain fell, and the growth rate of the higher feature point was higher. The affected area was concentrated on the upper part of the surface about 0.75 m. With the increasing of rainfall intensity, the slope surface getting to transient saturation state was quick, and the time of the PWP increasing to 0 among the feature points of same elevation was shortened. Meanwhile, the PWP presented a positive value, and as the infiltration depth increased, the transient saturation region expanded. The safety coefficient of the multistage filled slope was continuously reduced; after the stop of rainfall, the VWC and the PWP decreased, and the decline rate of the higher feature points was higher. In addition, the PWP of the lower part increased, and the safety factor of the slope presented a trend of rebound.

Soil Water Characteristic Curve for a Granite Residual Soil: Experimental and Numerical Results

2011 ◽  
Vol 312-315 ◽  
pp. 1172-1177 ◽  
Author(s):  
A. Topa Gomes ◽  
A. Viana Da Fonseca ◽  
A. Silva Cardoso
Keyword(s):  
Experimental Data ◽  
Soil Water ◽  
Characteristic Curve ◽  
Residual Soil ◽  
Seepage Analysis ◽  
Soil Water Characteristic Curve ◽  
Granite Residual Soil ◽  
Definition Of ◽  
Paper Method ◽  
Geotechnical Problems

The seepage analysis in geotechnical problems, namely in excavations, was typically performed assuming saturated conditions in the ground. It is now know that the flow in the non saturated part of the ground assumes also relevant importance and hence it is vital to characterize its behaviour. The Soil Water Characteristic Curve (SWCC) of the soil is probably the most important parameter in defining this behaviour and particularly for estimating the permeability of the soil. This paper presents the definition of the SWCC for a granite residual soil using pressure plates and the filter paper method. Based on experimental data some equations are adjusted and the results obtained are discussed. At the end of the paper some predictions of the non saturated permeability of the ground are also performed.

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