Elizabeth Theron
56871265300
Publications - 7
Relationships between Shear Strength Parameters with Mineralogy and Index Properties of Compacted, Unsaturated Soils
Publication Name: Studia Geotechnica Et Mechanica
Publication Date: 2025-03-01
Volume: 47
Issue: 1
Page Range: 65-88
Description:
The objective of this study is to assess the influences of soil index properties, swelling parameters, and soil mineralogy on unsaturated shear strength parameters (φ', φb, c') of compacted expansive soils. The laboratory tests include the grain size distribution, specific gravity (Gs), Atterberg limits, swelling potential, X-ray diffraction, modified Proctor compaction, soil suction, and triaxial testing. MINITAB 19 statistical analysis software generates the tri-dimensional surface graphs. The values φ', φb, and c"are majorly influenced by water (%), Gs, and clay (%). φ"shows a strong correlation with free swell ratio (FSR), free swell index (FSI), and void ratio. φb demonstrates a strong relationship with liquid limit, plasticity index, and γd (dry unit weight). φ"and c"portray a moderate relationship with liquid limit, plasticity limit, and γd. φ"exhibits a moderate correlation with smectite (%) and plagioclase (%). φb describes a strong relationship with smectite (%) and a moderate correlation with plagioclase and K-feldspar (%). c"depicts a moderate correlation with smectite (%), K-feldspar (%), and plagioclase (%). The matric suction controls the behaviour of unsaturated soils. Nonetheless, the influences of soil index properties, swelling potential, and mineralogy on shear strength are not marginal. These findings provide a good insight into the behaviour of unsaturated expansive soils and contribute to enhancing geotechnical modelling.
Open Access: Yes
Evaluation of the Unsaturated Shear Strength Parameters of Compacted, Heaving Soil Using Geotechnical Properties
Publication Name: E3s Web of Conferences
Publication Date: 2023-04-24
Volume: 382
Issue: Unknown
Page Range: Unknown
Description:
The shear strength is a fundamental property of soil material under structural loads. The determination of shear strength properties of unsaturated soils is challenging and time-consuming. Geotechnical predictive models can be utilized to assess the unsaturated shear strength of heaving soil. This study attempts to propose predictive models to evaluate the unsaturated shear strength parameters of compacted heaving soil. These parameters include the angle of internal friction associated with the net normal stress (φ), angle indicating the rate of increase in shear strength with respect to a change in matric suction (φb), and effective cohesion (c'). The geotechnical properties of soils were assessed through laboratory tests such as particle size distribution, consistency limits, specific gravity, modified Proctor compaction test, swelling test, suction test, and advanced triaxial testing. Multivariate analysis was conducted using NCSS 12 software to design the models. The validation of models includes the determination coefficient, probability value, comparing experimental values with predicted values, and comparing the developed models with other model found in recent literature. The models engineered in this study can estimate the unsaturated shear strength parameters of compacted heaving soil with acceptable precision.
Open Access: Yes
Estimation of optimum moisture content and maximum dry unit weight of fine-grained soils using numerical methods
Publication Name: Walailak Journal of Science and Technology
Publication Date: 2021-08-15
Volume: 18
Issue: 16
Page Range: Unknown
Description:
Soil compaction is one of the basic engineering techniques, which is carried out to guarantee the stability of soils dependent on specified strength. Nonetheless, in large-scale construction projects, the estimation of compaction features required tremendous effort and time that can be saved utilizing empirical relationships at the initial phases. It becomes critical to develop models to predict the compaction features, namely the maximum dry unit weight (γdmax ) and optimum water content (WOP ). This article attempts to develop models to predict the γdmax and WOP of fine-grained clay soils. Geotechnical tests such as grain size distribution, Atterberg limits, specific gravity, and proctor compaction tests are performed to assess soil samples' physical and hyro-mechanical characteristics. Multivariate analysis is conducted using MINITAB 18 software to develop the predictive models. The validation process of developed models includes the determination coefficient, probability value (p-value), comparison of the predicted values with experimental values, comparison of the models proposed in this study with other existing models found in the recent literature, and employing a different soil data set. The predicted values obtained from the models proposed in this research project are more accurate than other models developed recently. The proposed models estimate the compaction features of fine-grained clay soils with acceptable precision.
Open Access: Yes
Stabilization of Expansive Soils Using Mechanical and Chemical Methods: A Comprehensive Review
Publication Name: Civil Engineering and Architecture
Publication Date: 2021-08-01
Volume: 9
Issue: 5
Page Range: 1289-1294
Description:
The presence of expansive soils on construction sites is problematic in geotechnical engineering. The swell-shrink behaviour makes these soils not suitable to be used in their natural state. The expansive soil damages cause financial loss yearly more than floods, hurricanes, tornadoes, and earthquakes combined. Moreover, the cost of cut to spoil of expansive soils during construction projects has continued to rise because of the high cost of earthworks, haulage, and the increasing scarcity of spoil areas because of the built environment. Nonetheless, a proper stabilization technique can significantly enhance the expansive soil's properties. The research project attempts to review, report the limits and merits of mechanical and chemical methods utilized to stabilize expansive soils in line with their efficiency, environmental concerns, and cost-effectiveness. A review of mechanical and chemical treatment techniques is conducted in this regard. Ultimately, each stabilization method exhibits its merits and limitations. The lack of standards for the treatment of swelling soils is a significant problem in engineering practice. Specialists in the domain of soil treatment must work together to obtain an optimized stabilization approach and protocol. Moreover, engineers should perform a geoenvironmental assessment appropriate for chemical stabilization methods and additives utilized. This research work contributes as a guideline in the selection and application of chemical and mechanical stabilization methods.
Open Access: Yes
Models for predicting the suction of heaving compacted soils using geotechnical properties
Publication Name: Iop Conference Series Earth and Environmental Science
Publication Date: 2021-04-20
Volume: 727
Issue: 1
Page Range: Unknown
Description:
Soil suction is the major property that controls the behaviour of unsaturated soils. Suction estimation is challenging both in the lab and the field. Various instruments to measure the suction have been developed with the recent technological advancements. Nonetheless, there are still limitations in regards to the reliability, cost, suction range, accessibility, scope of activity, and appropriateness for use either within the field or lab settings. The filter paper method is probably the simplest procedure to measure the suction for the entire range both in the field and the lab. Nevertheless, the procedure takes time. To alleviate the requirement for conducting this test, it becomes imperative to develop mathematical predictive models for soil suction. In this study, a detailed survey was carried out across the Free State province, South Africa, and sampling points identified. Samples were tested for their geotechnical properties. The influence of the geotechnical properties on soil suction was studied. Multivariate regression analysis was carried out utilizing MINITAB 18 program to develop the mathematical predictive models.
Open Access: Yes
Investigation of the influencing soil parameters on the air entry values in soil-water characteristic curve of compacted heaving soils
Publication Name: Civil Engineering and Architecture
Publication Date: 2021-01-01
Volume: 9
Issue: 1
Page Range: 91-114
Description:
The air-entry value (AEV) is a fundamental parameter of the soil-water characteristic curve (SWCC). AEV is the minimum matric suction value required for entry of air into soil voids. The primary objective of this research work is to assess the impact of geotechnical index properties, swelling properties, mineral composition on AEV of compacted heaving soils, and discuss how they affect AEV. Soil properties were investigated through lab tests such as grain size distribution (GSD), specific gravity, Atterberg limits, linear shrinkage, free swell index, free swell ratio, X-ray diffraction, compaction test, and soil suction measurement. SWRC Fit program was used to perform non-linear fitting of the SWCC based on models VG, DB, FX, LN, and BL. Surface plot of data was used to characterize the impact of soil properties on AEV. It was observed that AEV is ranging from 10 kPa to 20.20 kPa, models DB and BL gives the best fitting SWCC. The percent of smectite mineral exhibits a significant impact on AEV. Swelling properties such as free swell index and free swell ratio influence the AEV with a respective determination coefficient of 85.72%, 88.68%. The plasticity index, linear shrinkage, specific gravity, and dry unit weight impact the AEV with a respective determination coefficient of 95%, 95.45%, 90.43%, 94.29%. The fine-grained content, clay fraction, void ratio, and water content influence the AEV with a respective determination coefficient of 97.95%, 84.89%, 80%, 94.31%. The finer the soil, the higher the AEV. The activity of clay and percent of illite mineral exhibit a marginal effect on the AEV.
Open Access: Yes
Semi-empirical model for predicting the swelling stress of compacted, unsaturated expansive soils
Publication Name: Civil Engineering and Architecture
Publication Date: 2021-01-01
Volume: 9
Issue: 1
Page Range: 225-239
Description:
Heaving soils are the most problematic worldwide. These soils develop swelling stress that produces uplift forces detrimental to the foundations. In engineering practice, swelling stress is not considered in general. Considering the swelling stress in foundation design enhances the service life of construction. The oedometer swelling test is the technique ordinarily used to assess the swelling stress. Nonetheless, the oedometer swelling test is cumbersome, time-consuming, making the test unattractive, and not cost-effective for the low-cost housing project. The objective of this research work is to propose a model to predict swelling stress as an alternative to oedometer testing. Geotechnical studies such as Atterberg limits, particle size distribution, free swell ratio, specific gravity, linear shrinkage, suction measurement, Proctor compaction test, and zero-swell test are performed to estimate the soil properties. Multivariate regression analysis is performed using NCSS.11 Program to develop the predictive model. The model is assessed base on the following: determining coefficient value, comparing predicted values with experimental values, comparing the proposed model with other existing models found in the literature. Besides, the Box-cox transformation function is used to improve the accuracy of the model. The developed model can be utilized to assess the swelling stress of compacted heaving soils, and it is much more accurate than other existing models.
Open Access: Yes
