The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Sastry Putcha - One of the best experts on this subject based on the ideXlab platform.
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evaluation of compaction methods for pipe trench backfill in areas of High Water Table
Transportation Research Record, 2000Co-Authors: Irtishad Ahmad, Sastry PutchaAbstract:Determining the density of backfill material and attaining the desired degree of compaction in the backfill under a High Water Table, typical operations in South Florida, present a difficult problem to the Florida Department of Transportation (FDOT) engineers and contractors. As a first step in seeking the solution to this problem, variations in soil conditions, determined by standard penetration test (SPT) N-values, that corresponded with varying methods of compaction were evaluated. In the experimental phase of the project, five field conditions were tested: Condition A, control dry, backfilling in the dry condition above Water; Condition B, dump soil, no compaction, backfilling under the Water Table, no tamping; Condition C, dump soil, compact per FDOT specifications, no deWatering, backfilling under the Water Table, tamping with a 2 by 4 as specified; Condition D, control wet, compact per FDOT specifications, deWatering during pipe installation and backfilling with periodic compaction according to FDO...
Paul Mcardle - One of the best experts on this subject based on the ideXlab platform.
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The comparison of experimental & theoretical uplift on a model structure due to a High Water Table
2020Co-Authors: Paul McardleAbstract:Uplift pressure can be defined as the hydrostatic force of Water exerted on or underneath a structure tending to cause a displacement of the structure. This force is quite common in structures such as dams and tunnels. Hydrostatic uplift can become significant when considering the size of structures such as dams or tunnels. However structural failures have occurred due to the failure to design for hydrostatic uplift. The purpose of this dissertation is to assess the forces that hydrostatic uplift can exert on a structure when it is subjected to a High Water Table using a flow net approach. An experimental analysis was constructed in a drainage and seepage tank to model the performance of the structure and the magnitude of the uplift forces as the level of Water Table varied. This dissertation contains a brief history of Hydrostatic Uplift, some failures which have occurred due to it and the theories associated with it. The theoretical and experimental results will be compared and discussed and conclusions will be drawn as to the reliability of the methods associated with analysing Hydrostatic Uplift. This paper concludes that analysing the effects of Hydrostatic Uplift by using a flow net approach, does provide a reasonable and conservative estimate of the actual hydrostatic pressure.
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the comparison of experimental theoretical uplift on a model structure due to a High Water Table
2014Co-Authors: Paul McardleAbstract:Uplift pressure can be defined as the hydrostatic force of Water exerted on or underneath a structure tending to cause a displacement of the structure. This force is quite common in structures such as dams and tunnels. Hydrostatic uplift can become significant when considering the size of structures such as dams or tunnels. However structural failures have occurred due to the failure to design for hydrostatic uplift. The purpose of this dissertation is to assess the forces that hydrostatic uplift can exert on a structure when it is subjected to a High Water Table using a flow net approach. An experimental analysis was constructed in a drainage and seepage tank to model the performance of the structure and the magnitude of the uplift forces as the level of Water Table varied. This dissertation contains a brief history of Hydrostatic Uplift, some failures which have occurred due to it and the theories associated with it. The theoretical and experimental results will be compared and discussed and conclusions will be drawn as to the reliability of the methods associated with analysing Hydrostatic Uplift. This paper concludes that analysing the effects of Hydrostatic Uplift by using a flow net approach, does provide a reasonable and conservative estimate of the actual hydrostatic pressure.
Irtishad Ahmad - One of the best experts on this subject based on the ideXlab platform.
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evaluation of compaction methods for pipe trench backfill in areas of High Water Table
Transportation Research Record, 2000Co-Authors: Irtishad Ahmad, Sastry PutchaAbstract:Determining the density of backfill material and attaining the desired degree of compaction in the backfill under a High Water Table, typical operations in South Florida, present a difficult problem to the Florida Department of Transportation (FDOT) engineers and contractors. As a first step in seeking the solution to this problem, variations in soil conditions, determined by standard penetration test (SPT) N-values, that corresponded with varying methods of compaction were evaluated. In the experimental phase of the project, five field conditions were tested: Condition A, control dry, backfilling in the dry condition above Water; Condition B, dump soil, no compaction, backfilling under the Water Table, no tamping; Condition C, dump soil, compact per FDOT specifications, no deWatering, backfilling under the Water Table, tamping with a 2 by 4 as specified; Condition D, control wet, compact per FDOT specifications, deWatering during pipe installation and backfilling with periodic compaction according to FDO...
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EVALUATION AND ANALYSIS OF CURRENT COMPACTION METHODS FOR FDOT PIPE TRENCH BACKFILLS IN AREAS OF High Water TableS
1999Co-Authors: Irtishad Ahmad, J D Mitrani, R A Baier, W C EpsteinAbstract:This research project was undertaken to examine the practicality and adequacy of the Florida Department of Transportation (FDOT) specifications regarding compaction methods for pipe trench backfills under High Water Table. Given the difficulty to determine density and to attain desired degree of compaction under High Water Table areas, typical in South Florida, it was alleged that the specification is difficult to follow. The main objective of this research project was to evaluate the variations in soil conditions, as determined by the Standard Penetration Test (SPT) N-values, as a result of varying methods of compaction. In Chapter 1, the scope and objectives of the research project are outlined. In Chapter 2, results of the literature search are reported and relevant materials that were found using the library and Internet resources are discussed. Chapter 3 contains a report on the investigation carried out on a few selected ongoing projects and some completed projects. In Chapter 4, the experimental field study is introduced. Descriptions of the five field conditions studied and the results of investigation are reported in this chapter. Analysis and interpretation of the results are presented in Chapter 5. Suggestions for further study are included and lessons learned are discussed in Chapter 6. In the last chapter, Chapter 7, conclusions of the study are Highlighted and recommendations for future actions by FDOT and potential researchers are outlined.
Shu Hui Yu - One of the best experts on this subject based on the ideXlab platform.
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ecological effects of soil salinity regulation through saline Water irrigation and subsurface drainage in High Water Table level area
Journal of Applied Ecology, 2016Co-Authors: Shu Hui YuAbstract:In High Water Table level area, saline Water irrigation in crucial drought periods has been confirmed to have a positive effect to increase crop yield while it may cause soil salt accumulation to have a potential negative effect on next season crop growth. It was supposed that eliminating or reducing this kind of negative effect could ensure a sustainable increase of crop yield under saline Water irrigation. Field experiments were completed in a 2year period in Nandagang district in coastal area of Hebei Province. We investigated the dynamic changes of soil salt accumulation under saline Water irrigation in dry season, and analyzed the ecological effect of removing soil salt storage by subsurface pipe drainage system in rainy or proper season. The results showed that the soil salinity experienced accumulation-desalinization-secondary accumulation under saline Water irrigation in dry season. In the early stage of irrigation, under 1 g·L -1 concentration saline Water irrigation treatment, the soil salt load was obviously removed in the layer of 0-50 cm, the soil salinity went up with soil depth, HCO3- content increased whereas other ions contents decreased; under 6 g·L- and 13 g·L-1 concentration saline Water irrigation treatments, the soil salt accumulated in the layer of 0-50 cm, the soil salinity went down with soil depth, HCO3-content decreased whereas other ions contents increased. Leaching effect of soil salt under subsurface pipe drainage system during rainy or proper season was significant. The soil desalinization ratio increased with the rainfall strength, ranging from 16.0% to 45.7%. On a yearly scale, the soil salt accumulation under saline Water irrigation was lower than that in control area. The wheat yield under saline Water irrigation was significantly Higher than that in control area, and the yield in the treatment of 1 g·L-1 was Highest.
Samera Norozpour - One of the best experts on this subject based on the ideXlab platform.
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the contribution of shallow groundWater by safflower carthamus tinctorius l under High Water Table conditions with and without supplementary irrigation
Irrigation Science, 2013Co-Authors: Houshang Ghamarnia, Mohsen Golamian, Saloome Sepehri, I Arji, Samera NorozpourAbstract:Lysimetric experiments were conducted to determine the contribution made by groundWater to the overall Water requirements of safflower (Carthamus tinctorius L.). The plants were grown in 24 columns, each having a diameter of 0.40 m and packed with silty clay soil. The four replicate randomized complete block factorial experiments were carried out using different treatment combinations. Six treatments were applied during each experiment by maintaining groundWater, with an EC of 1 dS m−1, at three different Water Table levels (0.6, 0.8 and 1.10 m) with and without supplementary irrigation. The uptake of groundWater as a part of crop evapotranspiration was measured by taking daily readings of the Water levels found in Mariotte tubes. The supplementary irrigation requirement for each treatment was applied by adding Water (EC of 1 dS m−1). The average percentage contribution from groundWater for the treatments (with and without supplementary irrigation under Water Table levels of 0.6, 0.8 and 1.10 m) were found to be 65, 59, 38% and 72, 70, 47% of the average annual safflower Water requirement (6,466 m3 ha−1). The increase in groundWater depths under supplementary irrigation treatments from 0.6 to 0.80 and 1.10 m caused seed and oil yield reductions of (7, 23.10%) and (48.23, 65.40%), respectively.