Heat Transfer Between Concrete Bored Cast-In-Place Piles and Surrounding Frozen Soil in Ice-Rich Area
Issue:
Volume 5, Issue 5, October 2020
Pages:
102-107
Received:
10 August 2020
Accepted:
28 August 2020
Published:
19 September 2020
Abstract: Based on the concrete test of foundation pile and the heat transfer theory between pile and soil, the heat transfer rule of pile and soil in ice-rich tundra is studied. The results show that the heat flow of foundation pile can be divided into vertical and horizontal heat flows. The vertical heat flow mainly occurs at the top of the pile and reaches the maximum value of 15.36w /m2 on 3d. It caused the pile top temperature to drop so fast that it dropped below 0°C in 3d. The value of the horizontal heat flow is 2~3 times that of the vertical heat flow. Its distribution is in descending order: the middle, the top and the bottom of the pile. The maximum temperature difference between pile center and pile wall is 6.8°C because of transverse heat flow. Local high temperature zone is formed inside the pile due to the relatively slow absorption process of thawing permafrost. Then the temperature dropped rapidly, reaching 0°C at 28d. The maximum disturbance radius in the frozen soil reaches 1.5m. Insulation layer can be added to the outside of the foundation pile during construction to obtain more uniform concrete temperature field, so as to improve the concrete strength and reduce the disturbance to the frozen soil. The construction period should be in summer.
Abstract: Based on the concrete test of foundation pile and the heat transfer theory between pile and soil, the heat transfer rule of pile and soil in ice-rich tundra is studied. The results show that the heat flow of foundation pile can be divided into vertical and horizontal heat flows. The vertical heat flow mainly occurs at the top of the pile and reache...
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Experimental Investigation of Utilizing Steel Fiber as Concrete Reinforcement in Bridge Decks
Issue:
Volume 5, Issue 5, October 2020
Pages:
108-113
Received:
26 August 2020
Accepted:
17 September 2020
Published:
23 September 2020
Abstract: The study aims to investigate and test the behavior of steel fiber reinforcement concrete material at different dosage of fibers in concrete bridge decks. Concrete is a brittle material therefore the tensile resistance of concrete is low. Steel fiber reinforcement concrete material is a developed material that has been proposed to improve the tensile behavior of the concrete. Steel Fiber Reinforcement is popular material that is being studied to improve the structural behavior of reinforced concrete under different load conditions. Steel fiber-reinforced concrete (SFRC) provides improved tensile performance of concrete. This improved performance can be used in slabs to reduce the volume of conventional steel reinforcement, create longer spans, or reduce slab thickness. The project consisted of twelve concrete slabs has dimensions of (45 inches x 20 inches x 3.5 inches), twelve cylinders has dimensions of (6 inches diameter x 12 inches height) for split tensile test, twelve cylinders has dimensions of (4 inches diameter x 8 inches height) for compression test and twelve beams has dimensions of (6 inches x 6 inches x 20 inches) for modulus of rupture test. each three concrete slabs and specimens has same dosage of steel fiber reinforcement starting with 0.0%, 0.5%, 1.0% and 1.5% in order to investigate and exam the concrete behavior. The experiment revealed that the increase in the dosage of steel fiber fraction increases the compressive strength of the concrete in addition to that the breakout strength of concrete in tension increased. It is also found that the steel fiber improves the ductility of concrete and that is clear in the “Load- Deflection response figures” the area under the curves increases compare with normal concrete while the crack width became thinner with the increasing of the steel fiber dosage and preventing the sudden collapse as in normal concrete. Taking those results into consideration this can make a reduction in structural weight and improve the safety and speed up the construction and cost saving in the short term and the long term.
Abstract: The study aims to investigate and test the behavior of steel fiber reinforcement concrete material at different dosage of fibers in concrete bridge decks. Concrete is a brittle material therefore the tensile resistance of concrete is low. Steel fiber reinforcement concrete material is a developed material that has been proposed to improve the tensi...
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Issues and Problems of Community Water Supply Schemes with Special Reference to Nepal
Gunjan Gautam,
Khet Raj Dahal
Issue:
Volume 5, Issue 5, October 2020
Pages:
114-125
Received:
1 September 2020
Accepted:
17 September 2020
Published:
23 September 2020
Abstract: Drinking water is a basic need for survival and good health of human beings as well as for any form of life on earth. In the absence of potable water, there is a high risk of transmission of serious diseases among people, like diarrhea, dysentery, cholera, and typhoid. Despite significant progress on community water schemes, worldwide still 2.2 billion people are out of access to safely managed water services. This study was conducted during the period from February to July 2020. Published literature such as paper, thesis, manuals, database, reports, and standards were collected from different sources and went on thoroughly. The conclusions are drawn based on studied materials. The study found that about 829 thousand people are estimated to die each year from diarrhea because of unsafe contaminated drinking water, sanitation, and hand hygiene. In South Asia, over 134 million people still do not have access to clean drinking water. Various studies have shown that progress on basic water supply in Nepal has reached up to 89% of the population by the end of 2019. Community drinking water schemes in Nepal are facing various types of problems, such as technical problems related to, gender equity and social inclusion (GESI), cost recovery and affordability, operation and maintenance, institutional, and legal framework. Because those problems on water schemes are not timely and appropriately addressed, there is always a high impact on un-functionality, poor service, and unsustainability. The study would like to suggest that the operation and maintenance funds should be managed after the implementation of the project. The capacity building training for the water users committee should be conducted before the handover of the schemes.
Abstract: Drinking water is a basic need for survival and good health of human beings as well as for any form of life on earth. In the absence of potable water, there is a high risk of transmission of serious diseases among people, like diarrhea, dysentery, cholera, and typhoid. Despite significant progress on community water schemes, worldwide still 2.2 bil...
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Modeling Climate Variability Influence on River Regime in Upper Njoro Catchment, Kenya
Edwin Otieno Amisi,
Peter Musula Kundu,
Raphael Muli Wambua
Issue:
Volume 5, Issue 5, October 2020
Pages:
126-137
Received:
16 September 2020
Accepted:
5 October 2020
Published:
13 October 2020
Abstract: To establish the effect of climate variability on annual discharge in Upper Njoro Catchment, hybrid models were developed by coupling Soil and Water Assessment Tool and Artificial Neural Networks. Daily surface runoff, lateral flow, and groundwater flow were first simulated with SWAT for the period (1978-1987) using climate variables from Egerton University weather station and LULC of 1978. The daily hydrologic variables simulated without calibration and validation of SWAT and observed discharge data were then used for ANN training, which led to the creation of discharge generation hybrid models for the dry, wet and wetter seasons. SWAT_ANN models generated discharges were compared with observed data and the performance rating were achieved at R2 (0.94, 0.91, 0.92) and NSE (0.89, 0.87, 0.87) for DJFM, AMJJ, and ASON seasons respectively. SUFI-2 algorithm in SWAT-CUP was run separately to compare the performance of SWAT with that of SWAT_ANN. SWAT-CUP sensitivity analysis revealed satisfactory values of both the p-factor (0.61) and the r-factor (0.69). Calibration and validation of monthly streamflow were realized at R2 (0.86 and 0.78) and NSE (0.83 and 0.74). The results showed that coupling SWAT and ANN improved flow prediction. Further, the potential of the SWAT_ANN modeling approach to separate the influence of climate variability on river regime from the effect of LULC was evaluated by comparing trends in the differences between observed and SWAT_ANN simulated monthly streamflow with trends of the quantified LULC changes. The findings provided sufficient evidence that the SWAT_ANN modeling approach was reliable and could also be applied to detect changes in LULC.
Abstract: To establish the effect of climate variability on annual discharge in Upper Njoro Catchment, hybrid models were developed by coupling Soil and Water Assessment Tool and Artificial Neural Networks. Daily surface runoff, lateral flow, and groundwater flow were first simulated with SWAT for the period (1978-1987) using climate variables from Egerton U...
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