• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • No language data
  • Tagged with
  • 26
  • 26
  • 26
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

PREDICTION TOOLS FOR SUBGRADE RESILIENT MODULUS

Kanika Gupta (20292747) 20 November 2024 (has links)
<p dir="ltr">Resilient Modulus (M<sub>R</sub>) is a fundamental parameter in the Mechanistic-Empirical Pavement Design Guide (MEPDG) that characterizes the stiffness of subgrade soils under repeated traffic loads. Traditionally, M<sub>R</sub> determination involves direct laboratory testing, which can be labor-intensive, costly, and impractical for large-scale pavement projects or rehabilitation efforts. To address these challenges, the current research has explored non-destructive testing methods, such as Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR), as well as the use of predictive models to estimate M<sub>R</sub> based on soil properties. This study aimed to enhance the understanding of M<sub>R</sub> testing and improve predictive models, contributing to more reliable and efficient M<sub>R</sub> estimation techniques.</p><p dir="ltr">The research involved an extensive experimental program, which began with the collection of subgrade soil samples from various road construction projects across Indiana. The collected soils were characterized through standard geotechnical tests, including gradation analysis, Atterberg limits, and compaction tests. Resilient modulus testing followed the AASHTO T 307 protocol, performed on both untreated and treated soil samples to simulate field conditions. Post-construction, the test sites were revisited to conduct FWD and GPR tests, ensuring a comprehensive dataset for correlating M<sub>R</sub> with field test results. The use of GPR for pavement thickness estimation proved effective in identifying discrepancies between as-built and design thicknesses in both flexible and rigid pavements. For flexible pavements, a strong correlation was observed between laboratory M<sub>R</sub> values and FWD backcalculated moduli, indicating that FWD testing can reliably estimate M<sub>R</sub> for untreated subgrade soils.</p><p dir="ltr">The study also explored the use of machine learning algorithms, such as random forest and gradient boosting, to predict M<sub>R</sub> based on soil properties, offering an alternative to traditional regression analysis. The research found that stress-independent models failed to yield statistically significant correlations between M<sub>R</sub> and basic soil properties such as moisture content, dry density, and Atterberg limits. In contrast, stress-dependent models, particularly the Uzan and octahedral models, revealed weak dependencies on confinement and deviatoric stresses, leading to significant variability in M<sub>R</sub> values across tested samples. The results highlight the limitations of current soil- and stress-based models, suggesting that while they may work well for specific cases, they cannot be generalized across a wide range of conditions.</p><p dir="ltr">An effort to compare soil performance during the different stages of resilient modulus testing and a numerical method that included a stress-dependent soil model confirmed the empirical finding of a weak dependency between M<sub>R </sub>and confinement and deviatoric stress. This was the case not only for the standard AASHTO T 307 protocol, but also for other protocols where the loading sequence was reversed compared to the standard test.</p><p dir="ltr">The research demonstrated the potential of machine learning for M<sub>R</sub> prediction and the complexity of the soil behavior during resilient modulus testing. Thus, models to accurately predict M<sub>R</sub> results should be able to follow the stress path that the soil is subjected to during the test.</p>
2

Study of cone penetration in silica sands using digital image correlation (DIC) analysis and x-ray computed tomography (XCT)

Eshan Ganju (11104863) 09 July 2021 (has links)
Cone penetration in sands is a complex process: it contains several challenges that geomechanicians face, such as large displacements, large strains, strain localization, and microscale phenomena such as particle crushing and sand fabric evolution. In order to gain a deeper understanding of the penetration process and the mechanisms controlling penetration resistance, capturing these displacement and strain fields and microscale phenomena is necessary. Furthermore, as more sophisticated theoretical models become available for the simulation of the cone penetration problem, the experimental validation of those methods becomes vital.<br><div><br></div><div>This dissertation presents a multiscale study of the cone penetration process in silica sands. The penetration problem is investigated using a combinational approach consisting of calibration chamber experiments, digital image correlation (DIC) analysis, and X-ray computed Tomography (XCT) scans. Three silica sands with different particle characteristics are used in the experimental program. These three sands have similar particle size distributions; however, they differ in particle morphologies and particle strengths. These differences allow a study of the effect of microscale sand properties on the macroscale response of the sands to the cone penetration process. The three silica sands used in this research are fully characterized using laboratory experiments to obtain particle size distributions, particle morphologies, particle crushing strengths, minimum and maximum packing densities, and critical-state friction angles. Subsequently, both dense and medium-dense samples of the three sands are compressed in a uniaxial loading device placed inside an X-ray microscope (XRM) and scanned at multiple stress levels during uniaxial compression. Results from uniaxial compression experiments indicate that: (1) the compressibility of the sands is closely tied to particle morphology and strength, and (2) the anisotropy in the orientations of interparticle contact normals generally increases with axial stress; however, this increase is limited by the occurrence of particle crushing in the sample.<br></div><div><br></div><div>Subsequently, cone penetration experiments are performed under different confinement levels on dense samples of the three sands in aspecial half-cylindrical calibration chamber equipped with DIC capabilities. For each penetration experiment, incremental displacement fields around the cone penetrometer are obtained using DIC analysis, and these incremental displacement fields are further analyzed to compute the incremental strain fields. A novel methodology is developed to obtain the shear-band patterns that develop around the penetrometer automatically. Furthermore, differences in the shear-band patterns in deep and shallow penetration environments are also investigated. Results show that strain fields tend to localize intensely near the penetrometer tip, and the shear bands tend to develop along the inclined face and near the shoulder of the penetrometer. Significant differences in the shear band patterns in deep and shallow penetration environments are also observed.<br></div><div><br></div><div>After each cone penetration experiment, a specially developed agar-impregnation technique is used to collect minimally disturbedsand samples from around the penetrometertip. These agar-impregnated sand samples are scanned in the XRM to obtain 3D tomography data, which are further analyzed to quantify particle crushing around the penetrometer tip. The results show that: (1) for a given sample density, the amount of crushing around the cone penetrometer depends on the confinement and the sand particle characteristics, (2) the level of crushing is not uniform around the penetrometer tip, with more severe crushing observed near the shoulder of the penetrometer, and (3) the regions with more severe particle crushing around the penetrometer approximately overlap with regions of high shear strain and volumetric contraction. A framework is also proposed to obtain the ratio of penetration resistance in more crushable sands to penetration resistance in less crushable sands. Furthermore, a novel resin-impregnation technique is also developed to collect undisturbedsand samples from around the penetrometer tip. The resin-impregnated sand sample collected after one of the penetration experiments is scanned in the XRM to obtain the 3D tomography data, which is then analyzed to obtain the distribution of interparticle contact normal orientations at multiple locations around the penetrometer tip. These analyses indicate that the interparticle contact normals tend to orient themselves with the incremental principal strains around the penetrometer: below the penetrometer tip, the interparticle contact normals orient vertically upwards, while closer to the shoulder of the penetrometer, the interparticle contact normals become more radially inclined.<br></div><div><br></div><div>Data presented in this dissertation on penetration resistance, incremental displacement fields, incremental strain fields, particle crushing, and interparticle contact normal orientations around the cone penetrometer are aimed to be useful to researchers working on the multiscale modeling of penetration processes in granular materials and aid in the further development of our understanding of penetration processes in sands.<br></div>
3

STUDY OF BEARING CAPACITY AND SETTLEMENT OF FOOTINGS IN SILICA SANDS USING DIGITAL IMAGE CORRELATION (DIC)

Firas H Janabi (12471888) 28 April 2022 (has links)
<p>  </p> <p>Knowledge of the displacement and deformation fields beneath foundation elements obtained from carefully executed experiments is required to validate state-of-the-art numerical simulations, which in turn enable the development of better foundation design methods. This dissertation presents the results of an experimental program in which load tests were performed on model footings in a half-cylindrical calibration chamber with a transparent viewing window across its diameter. The digital image correlation (DIC) method was used to obtain the strain and displacement fields in the soil from digital images taken during the tests. Tests performed on both smooth and rough footings show a significant dependence of resistance on footing base roughness, with the DIC results providing insight into the reasons for that dependence. The experimental bearing capacity results are used to validate a previously proposed method in which an equivalent friction angle is used for calculation of the bearing capacity of footings in sand.</p> <p>Schmertmann's method is one of the traditional methods for estimating the settlement of axially loaded footings in sand using cone penetration test (CPT) data. The method was developed for footings placed on the surface of a single, uniform sand layer; it assumes a depth of influence below the footing base within which most of the soil deformations take place and an influence diagram to quantify the influence factor as a function of depth. However, the literature contains limited information on the strain influence diagrams for footings on layered sands, and, as a result, there is no way to accurately account for the effect of sand layering on footing settlement. In this study, Schmertmann's approach for calculating the strain influence factor is modified to account for the effect of two sand layers with varying thickness and relative density. Penetration experiments were performed using a half-square model footing (width <em>B</em> = 90 mm) placed on the surface of both single and two-layered (dense over medium-dense and medium-dense over dense), air-pluviated, silica sand samples prepared inside a half-cylindrical calibration chamber designed for digital image correlation (DIC) analysis. The test results indicate that both the thickness and relative density of the top sand layer (the layer in contact with the footing base) affect the parameters of the strain influence diagram. For dense sand over medium-dense sand, the depth to the peak strain influence factor varies with the thickness of the dense layer; however, when the thickness of the dense layer is 1.5<em>B</em> or greater, the strain influence diagram is similar to that obtained for a single, uniform sand layer. In contrast, for medium-dense sand over dense sand, the peak value of the strain influence factor varies with the thickness of the medium-dense layer up to a value of 1<em>B</em>. Based on the results obtained in this study, new strain influence diagrams are proposed for settlement calculation of square footings on two-layered sand profiles. The proposed method for estimation of footing settlement in layered sand is validated against measured data obtained from a full-scale, instrumented footing load test reported in the literature. </p> <p>The expressions for the shape and depth factors available in the literature for bearing capacity calculation are mostly empirical and are based on results obtained using limit analysis or the method of characteristics assuming a soil that is perfectly plastic following an associated flow rule. This study presents the results of an experimental program in which load tests were performed on model strip and square footings in silica sand prepared inside a half-cylindrical calibration chamber with a transparent visualization window. The results obtained from the model footing load tests show a significant dependence of footing penetration resistance on embedment depth. The load test results were subsequently used to determine experimentally the shape and depth factors for model strip and square footings in sand. To obtain the displacement and strain fields in the sand domain, the digital image correlation (DIC) technique was used to analyze the digital images collected at different stages during loading of the model footing. The DIC results provide insights into the magnitude and extent of the vertical and horizontal displacement and maximum shear strain contours below and around the footing base during penetration.</p> <p>The loading of a footing in sand generates substantial shear bands as a mechanism for failure develops with the formation of slip surfaces. The interaction of sand particles in the shear band governs its constitutive response to loading. This study provides the results of loading experiments performed under different conditions on half-square model footings (width <em>B</em> = 90 mm) in dense air-pluviated silica sand samples prepared in a half-cylindrical calibration chamber equipped with an observation window that allows collection of images of the sand domain during testing. Two sands (Ottawa sand and Ohio Gold Frac sand) with different roundness (angularity) were used to perform these experiments. The digital image correlation (DIC) technique was used to obtain the incremental strain fields in the sand domain. The zero-extension line (ZEL) concept was then used to study the shear strain localization process and to obtain the orientation of the shear bands from analysis of the incremental strain fields. The results show that sand particle morphology, footing surface roughness, load eccentricity, and depth of embedment of the model footing have an impact on the dominant shear band patterns that develop below the model footings, and, as a result, all of these factors affect the unit bearing capacity of footings. The estimated thickness <em>t</em>s of the shear band from the experiments is approximately 6<em>D</em>50 for Ottawa sand and approximately 8<em>D</em>50 for Ohio Gold Frac sand. </p>
4

Effect of Climatic Changes on Subgrade Stiffness

Andrea Ardila Quiroga (7332803) 16 October 2019 (has links)
<p>There is consistent research evidence that shows improvement of the engineering properties of subgrade soils treated with lime or cement. However, limited information is available on the effect of climatic changes on the subgrade stiffness. The thesis studies the effects of changes in soil moisture content and temperature on the resilient modulus of treated and untreated subgrades in Indiana. Two types of soils were tested: A-6 and A-7-6, from two locations in Indiana: Hartford City and Bloomington, respectively. When existing standards ASTM D559/559-15 and ASTM D560/560-16 for wetting/drying (WD) and freezing/thawing (FT) processes, respectively, were followed, the treated and untreated samples failed through the process of preparation due to the stringent procedures in the standards. Appropriate test conditions were investigated, as part of the research, to develop new protocols more appropriate to the field conditions in Indiana. Two new test protocols were developed and successfully applied to the treated soils. A total of 26 resilient modulus, M<sub>R</sub>, tests were conducted following the standard AASHTO T307-99. The M<sub>R</sub> results showed that the repeated action of WD and FT cycles reduced the stiffness of the chemically-treated soils down to values similar to or lower than those of the untreated soils. However, when the amount of chemical was doubled, with respect to the optimum, the M<sub>R</sub> of the treated soils improved over that of the untreated soils, even after the wetting-drying cycles.</p>
5

FINITE ELEMENT MODELING OF BURIED ARCHED PIPES FOR THE ESTIMATION OF MAXIMUM FILL COVERS

Luz Maria Agudelo Urrego (7046339) 16 October 2019 (has links)
<div>The Indiana Department of Transportation implements maximum soil fill covers to ensure the safe installation and operation of buried pipes. Historically, fill cover tables are provided by INDOT, but the methodology for calculating these covers is not well documented. The finite element method enables a comprehensive analysis of the soil-pipe system taking into account soil conditions, pipe type and geometry, and conditions on the pipe-soil interface. </div><div><br></div><div>This thesis discusses the calculation of maximum fill covers for corrugated and structural plate pipe-arches using the finite element software CANDE and compares the results with previous estimates provided by INDOT. The CANDE software uses the Finite Element Method, and the Load and Resistance Factored design based on a two-dimensional culvert installation in a soil-pipe model. The model is set up under plain strain conditions and is subjected to factored dead and live load, and provides an analysis of the structure based on safety measures against all factored failure modes associated with the structural material.</div><div><br></div><div>Significant issues were encountered when calculating the maximum fill covers for pipe-arches in CANDE, including the inability of standard CANDE (Level 2 mesh) to model pipe-arches, lack of convergence for nonlinear analysis, and fill cover results higher than expected. To solve these issues, the pipe-arches were modeled using Level 3 solution in CANDE. The CANDE analyses were run using small-deformation analysis after buckling was eliminated as a governing failure mode using parallel simulations in Abaqus. Numerical results were compared to analytical solutions following ASTM standards.</div><div><br></div><div>The results showed that CANDE and INDOT calculations differ significantly, with the CANDE results yielding higher fill covers than those provided in INDOT specifications. These differences are attributed to the assumed loading pattern at failure. While the CANDE results assume that the maximum fill cover height is defined by the failure of the pipe considering the radial pressure (Pv), the INDOT results are consistent with results obtained by limiting the bearing capacity of the soil around the corner radius (Pc).</div>
6

Particle-Scale Effects on Pile Response During Installation and Loading

Ruben Dario Tovar-Valencia (6028821) 04 January 2019 (has links)
<p>In the last two decades, there has been significant improvements in pile design methods. These methods include variables that have been studied using laboratory and full-scale experiments. Refined understanding of the underlying mechanisms controlling pile response to loading enables introduction of variables in the design equations that reflect observations made in high-quality experimental data.</p><p>The mechanisms involved in the mobilization of the pile resistance (both base and shaft resistance) are studied in this thesis using a large-scale model pile testing facility consisting of a half-cylindrical calibration chamber with image analysis capabilities, instrumented model piles, and data and digital image acquisition systems. The thesis focuses on the effect of the pile surface roughness on the mobilization of tensile shaft resistance, the effect of the pile base geometry on the mobilization of base resistance, the analysis of possible mechanisms responsible for time-dependent increases in pile axial capacity, and particle crushing produced by pile installation. </p><p>A set of model pile tests were performed to study the effects of three different surface roughnesses on the shaft resistance of model piles jacked in the half-cylindrical calibration chamber. Digital images of the model piles and surrounding sand captured during tensile static loading were analyzed using the digital image correlation (DIC) technique. The base and shaft resistance measured for the instrumented model piles and the displacement and strain fields obtained with the DIC technique show that an increase in the roughness of the pile shaft results in an increase in the average unit shaft resistance and in the displacements and strains in the sand next to the shaft of the pile. Guidance is provided for consideration of pile shaft surface roughness in the calculation of the tensile limit unit shaft resistance of jacked piles in sand.</p><p>Base geometry effects were studied using jacked and pre-installed model piles with flat and conical bases tested in the DIC calibration chamber. The results show that the mobilized base resistance of a model pile with a conical tip was less than that of an equal pile with a flat base, all other things being equal, by a factor ranging from 0.64 to 0.84. The displacement and strain fields obtained with DIC also show that the slip pattern below the pile with a conical base differs from that of a pile with a flat base. </p><p>Finally, the degree of crushing of silica sand particles below the base of model piles jacked in sand samples is studied. The particle size distribution curves are obtained before and after pile installation. Relationships between the load mobilized at the base of the model piles and two well-known breakage parameters are proposed. This work also provides detailed measurements of the trajectories followed by crushed and uncrushed particles during pile installation, and characterizes the typical particle crushing modes produced by piles jacked in silica sand.</p><div><br></div>
7

Use of geosynthetics on subgrade and on low and variable fill foundation

Eirini Christoforidou (11819009) 19 December 2021 (has links)
<p>There are significant problems during construction to establish an adequate foundation for fills and/or subgrade for pavements when the natural ground has low-bearing soils. Geosynthetics such as geogrids, geotextiles and/or geocells could provide an alternative, less costly in time and money, to establish an adequate foundation for the fill and/or subgrade. There is extensive evidence in the literature and on DOTs practices about the suitability of using geotextiles in pavements as separators. Previous studies have also shown that the use of geogrids in flexible pavements as a reinforcing mechanism could decrease the thickness of the base layer and/or increase the life of the pavement. In this study, analyses of selected pavement designs using Pavement ME, while considering geogrid-enhanced base or subgrade resilient modulus values, showed that geogrid-reinforcement, when placed at the interface between subgrade and base, did not produce significant benefits, as only a modest increase in pavement life was predicted. In addition, parametric finite element analyses were carried out to investigate the potential benefits of placing a geogrid at the base of a fill over a localized weak foundation zone. The analyses showed that the use of geogrids is beneficial only when: (a) the stiffness of the weak foundation soil is about an order of magnitude smaller than the rest of the foundation soil; and (b) the horizontal extent of the weak foundation soil is at least 30% of the base of the embankment foundation. The largest decrease in differential settlements at the surface of the fill, resulting from geogrid-reinforcement, was less than 20% and, therefore, it is unlikely that the sole use of geogrids would be sufficient to mitigate differential settlements. Based on previous studies, a geocell mattress, which is a three-dimensional geosynthetic filled with different types of materials, could act as a stiff platform at the base of an embankment and bridge over weak zones in the foundation. However, given the limited experience on the use of geocells, further research is required to demonstrate that geocells can be effectively used instead of other reinforcement methods.</p>
8

CRACK INTERACTION WITH A FRICTIONAL INTERFACE IN A ROCK-MODEL MATERIAL: AN EXPERIMENTAL AND NUMERICAL INVESTIGATION

Danielli De melo moura (10277900) 06 April 2021 (has links)
Different rock formations may appear within the same mass, or even within the same formation there may exist layers of different materials, creating interfaces between layers (an interface may be defined, in more general terms, as a frictional contact that separates two similar or dissimilar materials). Currently, there is no well-established experimental work that investigates the influence of frictional interfaces, interface orientation and flaw geometries on crack behavior (i.e. initiation, propagation and coalescence) in brittle specimens under compressive loading. A series of experiments on homogeneous gypsum specimens, used as a rock-model material, containing two pre-existing open flaws and a frictional interface has been performed under uniaxial compression. The experiments investigate how cracks interact with interfaces and how different variables (i.e. flaw geometry, interface inclination angle and interface roughness) affect crack behavior in homogeneous materials separated by an interface. The specimens are 203.2mm high, 101.6mm wide, and 25.4mm thick. The two flaws, with 0.1mm aperture and 12.7mm length (2a), are created through the thickness of the specimen. The spacing (S) between flaws, continuity (C), and inclination angle, measured from the horizontal, (β) define the geometry of the flaws. Three flaw geometries are tested: S=0, C= -2a= -12.7mm, β= 30° (i.e. a left-stepping geometry); S= 2a= 12.7 mm, C=a=6.35 mm, β= 30° (i.e. an overlapping geometry) and S= 3a= 19.05mm, C=0, β= 30° (i.e. a right-stepping geometry). Smooth and rough unbonded interfaces are created by casting the specimen in two parts. The first half of the specimen is cast against a PVC block with an inclined face (i.e. 90°, 80° or 70°) with respect to the vertical axis of the specimen. The second half is then cast against the first one. Sandpaper may be attached to the PVC block to provide different roughness to the interface; a debonding agent applied to the interface ensures a cohesionless contact. In the experiments, digital image correlation (DIC) is used to monitor crack propagation on the specimen surface. The experiments indicate that the interface itself is an important contributor to new cracks and its presence in the specimens reduce crack initiation stress. Furthermore, the increase in roughness and inclination of the interface (i.e. from horizontal to 70° from the vertical) causes crack initiation stress to decrease. It was also observed that the angle between the incident crack plane and the interface affects whether an incident crack will penetrate an interface or be arrested: Tensile cracks that meet the interface at 30° to 60° angle get arrested, while those at or above 70° cross the interface with an offset of 0 – 1.2 mm. While shear cracks that meet the interface at 20° to 63° angles get arrested at the interface, while those at or above 70° cross the interface with an offset in the range of 0 – 1.76 mm. Another relevant finding is the fact that changes in interface roughness or inclination angle did not affect the angles at which cracks initiate or reinitiate at the interface.<div>A numerical study was conducted using the Extended Finite Element Method (XFEM) capability in ABAQUS, to further investigate the fracture behavior observed in the experiments and, more specifically, the influence of the different types of interfaces. An extensive investigation of the stress fields around the tips of the flaws and of the new cracks, as well as along the interface in the specimens, was conducted to determine the relationship between stresses and crack initiation and propagation (i.e. type and direction of cracks). The stress-based approach yields predictions of tensile and shear cracks location and initiation direction that are in good agreement with experimental results. The numerical investigation indicated that rougher horizontal interfaces induced slightly higher tensile stresses around the interior and exterior flaw tips than smoother interfaces, which may explain why tensile cracks at these locations initiated earlier in specimens with a rough interface. Moreover, inclined interfaces induced higher tensile stresses around the interior and exterior flaw tips than horizontal interfaces, which may justify that, in the experiments, inclined interfaces promoted crack initiation earlier than horizontal interfaces.</div>
9

Development of an Educational Tool for Deterministic and Probabilistic Slope Stability Analysis

Thiago Fernandes Leao (8098877) 10 December 2019 (has links)
<div>This research consists of the development of a new educational tool for calculations of 2D slope stability problems, named PNW-SLOPE. Slope stability has been considered one of the most important topics in geotechnical engineering for many years, so this is a subject which students should build a good background in the university. This program was created in Microsoft Excel with the aid of VBA (Visual Basic for Applications). The use of VBA allowed the creation of a good user interface, therefore those who are using the program can easily follow the instructions to create, analyze the model and check the results. Even though there are many commercial programs with the same application, this research presents a new alternative, more focused on educational purposes. PNW-SLOPE is divided in several modules.The first consists of the geometry definition of the slope. The second module consists of a deterministic slope stability analysis considering limit equilibrium method and the method of slices. The third module consists of a probability analysis considering Monte Carlo simulation. With these two options, users can compare both analysis and understand how important is the consideration of probability analysis in Geotechnical Engineering. This is a pertinent topic nowadays, since reliability analysis is increasingly being incorporated in standards and design codes throughout the world. An additional module was created for rock slope stability problems in which the failure results from sliding on a single planar surface dipping into the excavation. Several examples are presented to demonstrate some of the features of PNW-SLOPE and results are verified with commercial programs such as Geostudio Slope/w and Rocscience Slide 2018.</div>
10

STRENGTH-STIFFNESS CORRELATIONS FOR CHEMICALLY TREATED SOILS

Pranavkumar Shivakumar (12535903) 01 June 2022 (has links)
<p> The central theme of the study is to identify strength-stiffness correlations for chemically treated subgrade soils in Indiana. This was done by conducting Unconfined Compression (UC) tests and resilient modulus tests for soils collected at three different sites, namely : US 31, SR 37 and I-65. At each site, soil samples were obtained from 11 locations at 30 ft spacing. The soils were treated in the laboratory with cement, using the same proportions used for construction, and cured for 7 and 28 days before testing. Results from the UC tests were compared with the resilient modulus results that were available. No direct correlation was found between resilient modulus and UCS parameters for the soils investigated in this study. A brief statistical analysis of the results was conducted, and a simple linear regression model involving the soil characteristics (plasticity index, optimum moisture content and maximum dry density) along with UCS and resilient modulus parameters was proposed.  </p>

Page generated in 0.115 seconds