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B. R. Phanikumar - One of the best experts on this subject based on the ideXlab platform.
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Efficacy of Geopile–Anchors in Controlling Heave of Expansive Clay Beds
Geotechnical and Geological Engineering, 2020Co-Authors: B. R. PhanikumarAbstract:This paper presents the efficacy of a new technique in the form of geopile – anchors in arresting heave of Expansive soils. Heave behaviour of a remoulded Expansive Clay reinforced with vertical cylindrical cells made of geogrid and filled with geomaterials ( geopiles ) with a central anchor inside is presented. A geogrid cylinder installed vertically in an Expansive soil (forming a geopile), with an anchor inside is a geopile – anchor. In a geopile–anchor, foundation is anchored to an anchor plate at the bottom of the geopile with the help of an anchor rod. The upward movement of foundation due to swelling of Clay is resisted by anchorage and by friction mobilized at the interface formed by the fill material (Expansive soil)–geogrid–Expansive soil. Filling the geopile with granular material can augment uplift resistance. Tests were conducted on Expansive Clay beds reinforced with geopile–anchors varying geopile diameter and type of geopile-fill material. In the case of group of geopile–anchors, spacing was varied and its effect on heave studied. The experimental results indicated that geopile–anchors reduced heave of Expansive Clay beds. With Expansive Clay fill, a maximum reduction in heave of 78.50% was obtained. When gravel fill was used, a percentage reduction of 92.50% was obtained. At a radial distance of 60-mm the reduction in heave obtained was 50%, 58%, 67% and 73% for single geopile–anchor, and 69%, 73%, 81% and 88% for two group geopile–anchors installed at a spacing of 2d when the fill materials were Clay, fine sand, coarse sand and gravel respectively.
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Swelling Behaviour of an Expansive Clay Blended With Fine Sand and Fly Ash
Geotechnical and Geological Engineering, 2020Co-Authors: B. R. Phanikumar, Supriya Dembla, A. YatindraAbstract:This paper presents the effects of fine sand and fly ash on the swelling of an Expansive Clay. Fine sand and fly ash were used as additives at varying quantities. Free swell index (FSI), swell potential and swelling pressure were determined for the additive contents of 0%, 5%, 10%, 15%, 20% and 25%. FSI decreased by 29% and 50.32% respectively when fine sand content and fly ash content increased from 0 to 25%. Swell potential decreased by 80.4% and 32.7% respectively when fine sand content and fly ash content increased from 0 to 25%. While swelling pressure decreased by 84.6% when fine sand content increased from 0 to 25%, it did not show any trend with fly ash content.
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Volume change behaviour of an Expansive Clay blended with lime and pond ash – controlling swell
Quarterly Journal of Engineering Geology and Hydrogeology, 2020Co-Authors: B. R. PhanikumarAbstract:This paper presents the influence of lime content on free swell index (FSI) of an Expansive Clay powder passing through a 425 µm sieve and on some significant swell-compressibility characteristics of oven-dry, Expansive Clay with grains of a size
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compaction and strength characteristics of an Expansive Clay stabilised with lime sludge and cement
Soils and Foundations, 2020Co-Authors: B. R. Phanikumar, Ramanjaneya E RajuAbstract:Abstract The chemical stabilization of Expansive soils has been found to be quite successful in controlling detrimental volume changes due to swell-shrink behaviour. Lime, cement, CaCl2, fly ash, pond ash and other chemical reagents have been effective in stabilizing Expansive soils and improving their characteristics. The influence of lime sludge, a by-product of the paper industry, on the index properties of Expansive Clays was investigated. Their LL, PI and FSI, and the engineering characteristics of these Clays were measured after being treated, including their compaction characteristics, stress-strain behaviours at different curing periods and CBRs. The index and engineering properties of the Clay-lime sludge blends were studied for different lime sludge contents. As the compacted density did not show a satisfactory improvement upon addition of lime sludge, 10% cement was added to all the lime sludge-Clay blends to study its influence on the above properties of lime sludge–treated Expansive Clay. The addition of 10% cement resulted in lower LL, PI and FSI and higher densities, strengths and CBRs.
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Improving Expansive Clay beds with granular pile anchors (GPAs) and geogrid-encased GPAs
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2020Co-Authors: B. R. Phanikumar, Ammavajjala Sesha Sai Raghuram, Ajjarapu SriramaraoAbstract:Granular pile anchors (GPAs) are an innovative foundation technique developed for reducing the heave of Expansive Clay beds. Other engineering characteristics of Expansive Clay beds have also been ...
M. Muthukumar - One of the best experts on this subject based on the ideXlab platform.
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Shrinkage Behaviour of GPA-Reinforced Expansive Clay Beds Subjected to Swell–Shrink Cycles
Geotechnical and Geological Engineering, 2015Co-Authors: M. Muthukumar, B. R. PhanikumarAbstract:Expansive soils undergo alternate swelling and shrinkage respectively in rainy seasons when they absorb water and in summers when water evaporates from them. Hence, all types of foundations constructed in Expansive soils are also subjected to alternate swelling and shrinkage in rainy and summer seasons. As a result, super-structure members are also affected, undergoing severe distress. Various tension-resistant and innovative foundation techniques such as belled piers and under-reamed piles have been devised for arresting the problems posed by Expansive soils. Granular pile-anchor (GPA) is a recent innovative technique suggested for Expansive Clay beds. GPA is quite effective in controlling heave or swelling. Useful experimental heave data were obtained on laboratory scale and field scale GPAs. However, it is also necessary to study the behaviour of GPA-reinforced Expansive Clay beds subjected to swelling and shrinkage. This paper presents experimental data on shrinkage of GPA-reinforced Expansive Clay beds. Laboratory scale GPA-reinforced Expansive Clay beds were subjected to alternate swell–shrink cycles, each cycle for a duration of 300 days. Each Clay bed was subjected to three swell–shrink cycles (N = 1, 2 and 3), each cycle monitoring swelling for 10 days and shrinkage for 90 days. The number of GPAs (n) reinforcing the Clay beds was varied as 0, 1, 2 and 3. Shrinkage (mm) of a Clay bed, recorded in a given swell–shrink cycle, decreased with increasing number of GPAs (n). Further, shrinkage of a given Clay bed decreased significantly with increasing number of swell–shrink cycles (N) also. It was also found that shrinkage (mm) of a particular layer in the Clay bed decreased with increasing depth (z) of the layer from the top of the Clay bed.
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Swelling behaviour of GPA-reinforced Expansive Clay beds subjected to swell-shrink cycles
Geomechanics and Geoengineering, 2015Co-Authors: B. R. Phanikumar, M. MuthukumarAbstract:Granular pile-anchor (GPA) technique has been found to be an innovative foundation technique for Expansive Clays posing the dual problem of swelling and shrinkage. Swelling occurs during absorption of water and shrinkage during evaporation of water. Generally, in field Expansive Clay beds, swelling takes place during rainy seasons and shrinkage during summers. GPA is a recent innovative foundation technique devised to ameliorate the dual swell-shrink problem of structures founded on Expansive Clay beds. The other innovative techniques are drilled piers, belled piers and under-reamed piles. Laboratory scale model studies and field scale experiments on GPAs yielded useful results and revealed that swelling of Expansive Clay beds was effectively controlled by GPA technique. Studies on swell-shrink behaviour of GPA-reinforced Clay beds have not been performed so far. This paper presents results obtained from laboratory scale model studies on GPA-reinforced Expansive Clay beds subjected to alternate cycles of ...
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shrinkage behaviour of gpa reinforced Expansive Clay beds subjected to swell shrink cycles
Geotechnical and Geological Engineering, 2015Co-Authors: M. Muthukumar, B. R. PhanikumarAbstract:Expansive soils undergo alternate swelling and shrinkage respectively in rainy seasons when they absorb water and in summers when water evaporates from them. Hence, all types of foundations constructed in Expansive soils are also subjected to alternate swelling and shrinkage in rainy and summer seasons. As a result, super-structure members are also affected, undergoing severe distress. Various tension-resistant and innovative foundation techniques such as belled piers and under-reamed piles have been devised for arresting the problems posed by Expansive soils. Granular pile-anchor (GPA) is a recent innovative technique suggested for Expansive Clay beds. GPA is quite effective in controlling heave or swelling. Useful experimental heave data were obtained on laboratory scale and field scale GPAs. However, it is also necessary to study the behaviour of GPA-reinforced Expansive Clay beds subjected to swelling and shrinkage. This paper presents experimental data on shrinkage of GPA-reinforced Expansive Clay beds. Laboratory scale GPA-reinforced Expansive Clay beds were subjected to alternate swell–shrink cycles, each cycle for a duration of 300 days. Each Clay bed was subjected to three swell–shrink cycles (N = 1, 2 and 3), each cycle monitoring swelling for 10 days and shrinkage for 90 days. The number of GPAs (n) reinforcing the Clay beds was varied as 0, 1, 2 and 3. Shrinkage (mm) of a Clay bed, recorded in a given swell–shrink cycle, decreased with increasing number of GPAs (n). Further, shrinkage of a given Clay bed decreased significantly with increasing number of swell–shrink cycles (N) also. It was also found that shrinkage (mm) of a particular layer in the Clay bed decreased with increasing depth (z) of the layer from the top of the Clay bed.
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reducing heave of Expansive Clay beds through granular pile anchor groups
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2014Co-Authors: B. R. Phanikumar, M. MuthukumarAbstract:The granular pile-anchor (GPA) foundation system, a more recent technique, has also been found to be quite successful in controlling heave of Expansive Clay beds. This paper presents experimental data obtained from laboratory-scale heave tests conducted on an unreinforced Expansive Clay bed (n = 0) and Expansive Clay beds reinforced by a single GPA (n = 1), twin GPAs (n = 2) and a group of GPAs laid in equilateral triangular pattern (n = 3). The thickness of all the test Clay beds was 200 mm. Heave was monitored at different depths of Clay beds as they were inundated. Ground heave (or surface heave) was also monitored at different radial distances (r) from the centre of the test tank. The unreinforced Clay bed and the GPA-reinforced Clay beds were identical with regard to thickness (H), placement water content (w%) and dry density (γd). Heave decreased at all depths of the Clay beds as the number of the GPAs (n) increased. Furthermore, heave decreased with increasing depth (z) from the top of the Clay bed...
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Reducing heave of Expansive Clay beds through granular pile–anchor groups
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2014Co-Authors: B. R. Phanikumar, M. MuthukumarAbstract:The granular pile-anchor (GPA) foundation system, a more recent technique, has also been found to be quite successful in controlling heave of Expansive Clay beds. This paper presents experimental data obtained from laboratory-scale heave tests conducted on an unreinforced Expansive Clay bed (n = 0) and Expansive Clay beds reinforced by a single GPA (n = 1), twin GPAs (n = 2) and a group of GPAs laid in equilateral triangular pattern (n = 3). The thickness of all the test Clay beds was 200 mm. Heave was monitored at different depths of Clay beds as they were inundated. Ground heave (or surface heave) was also monitored at different radial distances (r) from the centre of the test tank. The unreinforced Clay bed and the GPA-reinforced Clay beds were identical with regard to thickness (H), placement water content (w%) and dry density (γd). Heave decreased at all depths of the Clay beds as the number of the GPAs (n) increased. Furthermore, heave decreased with increasing depth (z) from the top of the Clay bed...
Raghuveer P Rao - One of the best experts on this subject based on the ideXlab platform.
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crystalline and osmotic swelling of an Expansive Clay inundated with sodium chloride solutions
Geotechnical and Geological Engineering, 2013Co-Authors: Sudhakar M Rao, T Thyagaraj, Raghuveer P RaoAbstract:Compacted Expansive Clays swell due to crystalline swelling and osmotic/double layer swelling mechanisms. Crystalline swelling is driven by adsorption of water molecules at Clay particle surfaces that occurs at inter-layer separations of 10–22 A. Diffuse double layer swelling occurs at inter-layer separations >22 A. The tendency of compacted Clay to develop osmotic or double layer swelling reduces with increase in solute concentration in bulk solution. This study examines the consequence of increase in solute concentration in bulk solution on the relative magnitudes of the two swelling modes. The objective is achieved by inundating compacted Expansive Clay specimens with distilled water and sodium chloride solutions in free-swell oedometer tests and comparing the experimental swell with predictions from Van’t Hoff equation. The results of the study indicate that swell potential of compacted Expansive Clay specimens wetted with relatively saline (0.4, 1 and 4 M sodium chloride) solutions are satisfied by crystalline swelling alone. Comparatively, compacted Clay specimens inundated with less saline solutions (0.005–0.1 M sodium chloride) require both crystalline and osmotic swelling to satiate the swell potential.
Shahid Azam - One of the best experts on this subject based on the ideXlab platform.
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volume change behavior of a fissured Expansive Clay containing anhydrous calcium sulfate
Fourth International Conference on Unsaturated Soils, 2006Co-Authors: Shahid Azam, Ward G WilsonAbstract:Expansive Clays in eastern Saudi Arabia are generally fissured and contain high quantities of anhydrous calcium sulfate. Similar to Clay minerals, this secondary mineral causes swelling when hydrated and forms gypsum that, in turn, dehydrates and transfers back to anhydrite during compression. The main objective of this paper was to understand the volume change behavior of a local Expansive Clay containing 50 percent anhydrous calcium sulfate. Swelling and consolidation tests were conducted on undisturbed field samples according to the constant volume method. A conventional oedometer sample was used to determine the maximum possible volume change. Likewise, a large-scale oedometer sample was used to capture the influence of fissuring on volume change. The large-scale sample was thoroughly instrumented to determine both the vertical and the lateral swelling pressure. Results indicated a two-fold increase in swelling pressure of the desiccated Clay when corrections were applied to account for sample disturbance. The corrected vertical swelling pressure of the Clay was 320 kPa for the conventional sample and 245 kPa for the large-scale sample. The lateral swelling pressure was 40 percent of the vertical swelling pressure and the swelling index was one-third of the compression index for the investigated soil.
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influence of gypsification on engineering behavior of Expansive Clay
Journal of Geotechnical and Geoenvironmental Engineering, 2000Co-Authors: Sahel N Abduljauwad, Shahid AzamAbstract:Volume change in argillaceous sediments can take place due to either swelling of Expansive Clay or gypsification of anhydrous calcium sulfate. Gypsification offers a variety of serious geotechnical hazards such as high swell pressure, floor heave in tunnels, massive rock uplift in dams, and damages to light structures and pavements. Some of these phenomena have been observed in the Arabian Gulf coastal region, where the behavior of local argillaceous sediments is controlled by severe climatic and environmental conditions. Based on laboratory investigation of natural and synthetic samples, this paper studies the influence of gypsification of anhydrite on the engineering behavior of calcareous Expansive Clay.
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Effects of Calcium Sulfate on Swelling Potential of an Expansive Clay
Geotechnical Testing Journal, 2000Co-Authors: Shahid Azam, Sahel N Abduljauwad, Naser A. Al-shayea, Omar S. Baghabra Al-amoudiAbstract:Due to a reversible hydration-dehydration reaction, calcium sulfate undergoes phase transformations between a hydrated phase, gypsum, and a dehydrated phase, anhydrite. Due to the harsh climatic and environmental conditions in eastern Saudi Arabia, such phase changes add to the potential swelling hazards of local Expansive Clays. The adsorption of water by Expansive soils and the hydration of anhydrite to gypsum create swelling pressure and are the sources of much damage to foundations throughout the world. This paper attempts to assess the swelling caused by the interaction of calcium sulfate phases, especially gypsum and anhydrite, with Expansive Clay. This assessment was primarily based on studying the geotechnical, mineralogical, and volume change characteristics of calcium sulfate-bearing soils. X-ray and thermal analyses were used to estimate the type and amount of minerals present during phase transformation of calcium sulfate. The swelling potential was determined using an improved version of the simple odometer and constant-volume tests. The conventional odometer is the device normally used in these tests. However, the size of soil samples, the complete confinement, and the rigidity of the conventional odometer impose serious limitations on the application of the laboratory results to actual field problems. Therefore, the authors investigated the use of a large-scale odometer with different mold sizes and shapes on the swelling potential of some mixtures of Expansive Clay and calcium sulfate phases. In addition, the soil fabric of these mixtures was investigated using scanning electron microscopy to explain the volume change behavior. The results of this investigation indicated that the swelling potential of Clay-calcium sulfate mixtures decreased as the percentage of calcium sulfate was increased, and this reduction was more pronounced when gypsum was used. Swelling pressure was observed to be the highest in the conventional odometer and lowest in the large-scale square odometer mold.
Ward G Wilson - One of the best experts on this subject based on the ideXlab platform.
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volume change behavior of a fissured Expansive Clay containing anhydrous calcium sulfate
Fourth International Conference on Unsaturated Soils, 2006Co-Authors: Shahid Azam, Ward G WilsonAbstract:Expansive Clays in eastern Saudi Arabia are generally fissured and contain high quantities of anhydrous calcium sulfate. Similar to Clay minerals, this secondary mineral causes swelling when hydrated and forms gypsum that, in turn, dehydrates and transfers back to anhydrite during compression. The main objective of this paper was to understand the volume change behavior of a local Expansive Clay containing 50 percent anhydrous calcium sulfate. Swelling and consolidation tests were conducted on undisturbed field samples according to the constant volume method. A conventional oedometer sample was used to determine the maximum possible volume change. Likewise, a large-scale oedometer sample was used to capture the influence of fissuring on volume change. The large-scale sample was thoroughly instrumented to determine both the vertical and the lateral swelling pressure. Results indicated a two-fold increase in swelling pressure of the desiccated Clay when corrections were applied to account for sample disturbance. The corrected vertical swelling pressure of the Clay was 320 kPa for the conventional sample and 245 kPa for the large-scale sample. The lateral swelling pressure was 40 percent of the vertical swelling pressure and the swelling index was one-third of the compression index for the investigated soil.
