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Onyejekwe S.,Road Sector Development Team | Kang X.,Missouri University of Science and Technology | Ge L.,National Taiwan University
Bulletin of Engineering Geology and the Environment | Year: 2014

The use of correlations and empirical relationships in geotechnical engineering provides a fast, cost-effective means of predicting the value of a parameter based on the values of certain other, possibly more easily determined, parameters. The correlation between two or more soil properties has been found to be dependent in varying degrees on soil type, the testing method used to obtain the numerical value of the parameter itself and the homogeneity of the soil. Many empirical correlations among soil properties have been published. These correlations, based on widely sourced data, may not be appropriate for local situations. Hence, there is a need for correlations that are based on local data. This paper evaluated the validity of published empirical equations for the index of fine-grained soils in Missouri, USA. Four indices were used in the assessment including the root mean square error, the ratio of the estimated to laboratory-determined compression index, the ranking index and the ranking distance. Results reveal the overall best correlations for the Southeast Region and Other Regions of Missouri are given by Azzouz et al. (Soils Found 16:19-29, 1976). © 2014 Springer-Verlag Berlin Heidelberg.


Onyejekwe S.,Road Sector Development Team | Kang X.,Missouri University of Science and Technology | Ge L.,National Taiwan University
Engineering Geology | Year: 2016

The spatial variability of geotechnical parameters is determined in terms of their scale of fluctuation (SOF), θ. There are basically two approaches in analyzing the spatial variability of geotechnical parameters in order to determine their SOF. One uses an autocorrelation function (ACF) from random field theory and time series analysis and the other uses the semivariogram function (SVF) from geostatistics. Most of the published data on the spatial variability of geotechnical parameters were obtained using these methods, other methods include the local average theory and maximum likelihood method were also commonly adopted in the literature. The SOF, however, is not an inherent geotechnical property. Hence the SOF of a geotechnical parameter is dependent on factors such as geological setting, testing, and estimation methods among others. Since SOF is a non-inherent geotechnical property, it is expected that the SOF computed using different methods will give different values. Based on seven CPTu borings on predominantly soft clay in Hayti, Pemiscot County, Missouri, this paper presents an evaluation of the SOF estimated using both the ACF and the SVF with a view to determining the presence of any patterns to the difference and correlations between the two methods. © 2016 Elsevier B.V.


Onyejekwe S.,Road Sector Development Team | Ghataora G.S.,University of Birmingham
Bulletin of Engineering Geology and the Environment | Year: 2015

A selected commercially available sulphonated oil (SO) and a polymer were evaluated for use as soil stabilizers in a laboratory-based investigation. Two naturally occurring soils (Mercia mudstone [MM] and Oxford clay [OC]) and limestone quarry fines (LQF) were treated with the SO, a polymer, and a combination of the SO and the polymer for assessment of changes in their engineering properties. Untreated specimens also were tested to serve as a control condition. Stabilizer performance was evaluated based on the provisions of ASTM D4609-08 (2008). The test results indicated that performance was dependent on both the soil type and the stabilizer dosage. Generally, treatment did not lead to substantial changes in index properties or maximum dry density. However, the optimum moisture content for LQF was substantially reduced (17–35 %) together with improvements in both dry strength (unconfined compressive strength [UCS]: 38 % for MM, 26 % for OC, >500 % for LQF; static flexural strength [SFS]: 60 % for MM and OC, >500 % for LQF) and swell characteristics (20 % for OC, 21–61 % for MM). Applied in the proper context, the stabilizers are suitable for the treatment of soils for low-volume roads. © 2014, Springer-Verlag Berlin Heidelberg.


Onyejekwe S.,Road Sector Development Team | Onyejekwe S.,University of Birmingham | Ghataora G.S.,University of Birmingham
Journal of Materials in Civil Engineering | Year: 2014

The effect of randomly oriented discrete synthetic fiber inclusions on the properties of soils treated with proprietary liquid chemical stabilization additives was evaluated in a laboratory-based investigation. Mercia mudstone, Oxford clay, and limestone quarry fines were stabilized with a proprietary polymer and reinforced with discrete fibers. The findings were compared with untreated and reinforced specimens, which served as the control. Test results showed that the inclusion of randomly oriented discrete synthetic fibers had no significant effect on the compaction characteristics of the soils examined. However, it did result in significant improvements in the toughness of all soils examined and load retention after peak strength for Mercia mudstone and Oxford clay. Polymer/sulphonated oil-stabilized and fiberreinforced Mercia mudstone and Oxford clay specimens were found to be highly susceptible to moisture, while polymer-stabilized and reinforced limestone quarry fines specimens demonstrated good durability when submerged in water and retained 21 to 33% of their air-cured strengths. © 2014 American Society of Civil Engineers.


Onyejekwe S.,Road Sector Development Team | Ghataora G.S.,University of Birmingham
Bulletin of Engineering Geology and the Environment | Year: 2014

A selected commercially available sulphonated oil (SO) and a polymer were evaluated for use as soil stabilizers in a laboratory-based investigation. Two naturally occurring soils (Mercia mudstone [MM] and Oxford clay [OC]) and limestone quarry fines (LQF) were treated with the SO, a polymer, and a combination of the SO and the polymer for assessment of changes in their engineering properties. Untreated specimens also were tested to serve as a control condition. Stabilizer performance was evaluated based on the provisions of ASTM D4609-08 (2008). The test results indicated that performance was dependent on both the soil type and the stabilizer dosage. Generally, treatment did not lead to substantial changes in index properties or maximum dry density. However, the optimum moisture content for LQF was substantially reduced (17–35 %) together with improvements in both dry strength (unconfined compressive strength [UCS]: 38 % for MM, 26 % for OC, >500 % for LQF; static flexural strength [SFS]: 60 % for MM and OC, >500 % for LQF) and swell characteristics (20 % for OC, 21–61 % for MM). Applied in the proper context, the stabilizers are suitable for the treatment of soils for low-volume roads. © 2014 Springer-Verlag Berlin Heidelberg.


Onyejekwe S.,Road Sector Development Team | Ghataora G.S.,University of Birmingham
Journal of Materials in Civil Engineering | Year: 2016

The effect of treating limestone quarry fines (LQFs) with a commercially available liquid polymeric soil stabilizer, and a combination of the polymeric soil stabilizer and a small quantity (4%) of portland cement was evaluated. The research reported in this paper, which consisted of tests on both treated and untreated mixes, with the aim of evaluating the use of LQF in pavement construction was comprised of the following tests: (1) compaction, (2) unconfined compressive strength, (3) static flexural strength, and (4) durability. Test results showed marked improvements in the optimum moisture content, unconfined compressive strength, and static flexural strength, and no improvement in maximum dry density when polymer or both polymer and cement were added. Improvements in unconfined compressive strength were above the U.S. national requirements for admixtures for soil stabilization. Polymer-treated specimens were more susceptible to moisture than specimens treated with portland cement (PC) alone, and polymer plus PC. The latter showed the best durability when submerged in water. The LQF can be treated for low-volume road pavement applications with the stabilizers. © 2015 American Society of Civil Engineers.


Wang S.,Central South University | Luna R.,Saint Louis University | Onyejekwe S.,Road Sector Development Team
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2016

The postcyclic undrained monotonic shear behavior of Mississippi River Valley (MRV) silt is investigated by carrying out triaxial tests under various initial consolidation conditions. Results show that the variation of cyclic shear strength of MRV silt against initial overconsolidation ratio (OCR) and mean effective consolidation pressure (σc') was consistent with previous studies, i.e., it increased with both increase in OCR and decrease in σc'. The cyclic stress ratio (CSR) had no apparent effect on postcyclic shear behavior for MRV silt. At higher OCRs, the postcyclic reconsolidation behavior was more similar to recompression. Unlike the specimens not previously subjected to cyclic loading, the initial OCR did not influence effective stress path of the postcyclic reconsolidated specimens at the early stages of shearing. The normalized undrained shear strength (Su,OC/Su,NC) of MRV silt reconsolidated after cyclic loading increased with OCR. Stress-strain curves of MRV silt reconsolidated after cyclic loading can be normalized by σc' as those of the specimens not previously subjected to cyclic loading. Without reconsolidation, the liquefied specimens tend to dilate at the early stage of postcyclic undrained monotonic shearing phase. The undrained shear strength of the specimens not reconsolidated after cyclic loading did not approach to zero, and it increased with an increase in OCR. The undrained shear strength of postcyclic MRV silt can be predicted based on the equation Su = M/2 × P0' × 10-ψ/λ. However, cyclic loading changes the critical state line (CSL) of MRV silt, and the prediction will be better if the state parameter is computed based on the postcyclic CSL. © 2015 American Society of Civil Engineers.


Wang S.,Central South University | Luna R.,Saint Louis University | Onyejekwe S.,Road Sector Development Team
Soil Dynamics and Earthquake Engineering | Year: 2015

During earthquake events, low-plasticity silt undergoes a reduction in shear strength and stiffness due to development of excess pore pressure induced by cyclic loading. With reconsolidation, during which process excess pore pressure is dissipated, the shear strength and stiffness can be regained. However, due to the low permeability of silts (compared to sands), the dissipation of excess pore pressure and the reconsolidation of low-plasticity silt takes much more time. This paper investigates the postliquefaction shear behavior of Mississippi River Valley (MRV) silt at various degrees of reconsolidation using triaxial tests. Test results indicate that there was a steady increase, in shear strength and stiffness, at both large and small deformations, with increase in the degree of reconsolidation. The postliquefaction silt showed the effect of the apparent OCR, which had a close effect on postcyclic shear behavior as did the OCR on the static behavior. The critical state lines of MRV silt were different for pre- and post-liquefaction conditions. © 2015 Elsevier Ltd.

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