Soil Swelling Research Articles

The Use of Machine Learning Models and SHAP Interaction Values to Predict the Soil Swelling Index

Predicting the soil swelling index (CS) is crucial for geotechnical engineer to ensure the stability of civil engineering conceptions. Recently, ML models has sparked great interest from researchers in predicting the soil swelling index. However, due to the black-box nature of ML models, their prediction capabilities are still uninterpretable. This study aims to predict the soil swelling index using ML algorithms and interpret predictions. First, it employs the prediction capability of the Gaussian process regression (GPR) algorithm and compares it to the artificial neural network (ANN) for prediction the soil swelling index. Second, the SHAP algorithm as one recent explainable artificial intelligence (XAI) models is applied to interpret the predictions of the complex GPR and ANN models. The compiled experimental database covers 362 clayey samples gathered from different sites located in Northern Algeria. The modeling involved six input features, including the liquid limit (LL), plastic limit (PL), plasticity index (PI), water content (ωn), dry density (γd), and void ratio (e) to predict the soil swelling index. The findings based on statistical metrics showed a good performance of GPR with R2 = 0.78 and of ANN with R2 = 0.79. Comparative study based on Wilcoxon signed- rank test and sign test indicated that the ANN outperform better than GPR. Based on the interpretations obtained by SHAP algorithm, it is observed that the liquid limit (LL) and plastic limit (PL) are the two main input features that influence the CS, indicating, the higher content of LL and PL increase the model's output.

Evaluating the feasibility of inverted T foundation on expansive soils

This paper presents a comprehensive design study conducted in Saudi Arabia, focusing on the performance evaluation of an inverted T foundation system in a building constructed on expansive soils. The study aimed to investigate the causes of damage and evaluate the performance of a proposed inverted T foundation. A single story market building in a semi-arid region with expansive soil was constructed utilizing a 40 cm-thick mat foundation as a precautionary measure against soil swelling. However, the building experienced instability and damage shortly after completion. This study explored the replacement of the existing mat foundation with an inverted T foundation. The research involved assessing the ability of the inverted T foundation to withstand swelling pressures and its impact on the structural members of the building. Design guidelines and tools were developed to support the design and analysis of the inverted T foundation. Economic feasibility was also evaluated. The study compared the effects of swelling pressure on two types of foundations: a mat foundation and a rigid strip foundation. The results showed that the inverted T foundation demonstrated less upward movement and was found more effective in mitigating the detrimental effects of soil expansion compared to the mat foundation. Design guidelines and tools, including schedules, and charts were developed to support the design and analysis of the inverted T foundation. The findings have significant implications for the design and construction of buildings on expansive soils, offering insights into the effectiveness of the inverted T foundation as an alternative solution. The research contributes to the knowledge of foundation design on expansive soils in general and provides practical guidance for engineers and practitioners in similar geological contexts.

Improving Shear Strength and Microstructural Behavior of Black Cotton Soil Treated with Construction Demolished Waste

With its expansive character and low bearing capacity, black cotton soil presents considerable obstacles to construction projects. These challenges can be difficult to overcome. There is a tendency for it to rise and compress in response to variations in the amount of moisture present, and it also has weak strength properties, which makes construction activities more difficult. This study explores the possibility of stabilizing black cotton soil with recycled construction and demolition (C&D) waste in order to address these issues. Various C&D waste materials, like concrete, bricks, mortar, and other debris, are examined for their potential to enhance the shear strength of black cotton soil. The paper assesses the effectiveness of incorporating C&D waste blends ranging from 5% to 25% to mitigate soil swelling and shrinkage with improve shear strength. Previous to determining the soil's shear strength, index properties were assessed. Unconfined compression strength tests (UCS) are carried out on compacted specimens handled with C&D waste blends, with curing periods of 1 day, 7 days, and 28 days at room temperature. A comparison investigation showed that there was a comparable increase in UCS and a decrease in axial strain at failure as the amount of C&D waste in the soil rose. Micro-analyses displayed that the main factors prompting the interacting behavior of soil amended with C&D waste include changes in the gradation, cohesiveness, and the interplay between the particles, the mineralogical makeup, and the elemental, chemical, and microstructural components. The research aims to offer insights into sustainable methods for strengthening the performance of black cotton soil while reducing waste generation in construction activities.

A New Model for Evaluating the Behaviour of Swelling Soils

In many areas around the world, there are clayey soils that have the potential to change their volume caused by the variation in their water content. Increasing or decreasing the water content caused the clayey soils to swell or shrink, respectively. This phenomenon may cause the uplifting and settlement of structures, which may lead to considerable financial damages. The estimation of swelling displacement without addressing the swelling rate have been published by several research works. This drawback leads to the development of a new model that takes into account the swelling behavior of soils with time. The model, which consists of two hyperbolic curves, was compared with swelling test results performed on soil samples taken from several locations in Israel. Data test results were used to compare the newly introduced model with other existing mathematical models found in the literature. This analysis shows that the new model represents more accurately the behavior with time of the swelling clayey soils measured in laboratory test results than the existing hyperbolic models.

Experimental Study on the Properties of Basalt Fiber–Cement-Stabilized Expansive Soil

Expansive soil is prone to rapid strength degradation caused by repeated volume swelling and shrinkage under alternating dry–wet conditions. Basalt fiber (BF) and cement are utilized to stabilize expansive soil, aiming to curb its swelling and shrinkage, enhance its strength, and ensure its durability in dry–wet cycles. This study examines the impact of varying content (0–1%) of BF on the physical and mechanical characteristics of expansive soil stabilized with a 6% cement content. We investigated these effects through a series of experiments including compaction, swelling and shrinkage, unconfined compressive strength (UCS), undrained and consolidation shear, dry–wet cycles, and scanning electron microscope (SEM) analyses. The experiments yielded the following conclusions: Combining cement and BF to stabilize expansive soil leverages cement’s chemical curing ability and BF’s reinforcing effect. Incorporating 0.4% BFs significantly improves the swelling and shrinkage characteristics of cement-stabilized expansive soils, reducing expansion by 36.17% and contraction by 28.4%. Furthermore, it enhances both the initial strength and durability of these soils under dry–wet cycles. Without dry–wet cycles, the addition of 0.4% BFs increased UCS by 24.8% and shear strength by 24.6% to 40%. After 16 dry–wet cycles, the UCS improved by 38.87% compared to cement-stabilized expansive soil alone. Both the content of BF and the number of dry–wet cycles significantly influenced the UCS of cement-stabilized expansive soils. Multivariate nonlinear equations were used to model the UCS, offering a predictive framework for assessing the strength of these soils under varying BF contents and dry–wet cycles. The cement hydrate adheres to the fiber surface, increasing adhesion and friction between the fibers and soil particles. Additionally, the fibers form a network structure within the soil. These factors collectively enhance the strength, deformation resistance, and durability of cement-stabilized expansive soils. These findings offer valuable insights into combining traditional cementitious materials with basalt fiber to manage expansive soil hazards, reduce resource consumption, and mitigate environmental impacts, thereby contributing to sustainable development.

Effects of calcium amendments on hydraulic conductivity and sodium content of brine‐impacted soils

AbstractHigh concentrations of sodium chloride dominate oilfield produced waters (brine) of the Williston Basin. When accidental spills of produced waters occur, there is an immediate need to reduce concentrations of chloride, to protect surface and groundwater systems and to reduce concentrations of sodium (Na) in soil to prevent any unwanted swelling and dispersion in soil. Swelling and dispersion of soils will likely occur if sodium adsorption ratio values are too high and the electrical conductivity drops below a certain threshold that is required to maintain flocculation. To prevent this, a calcium (Ca) amendment can be applied to replace Na with Ca on soil exchange sites. Historically, gypsum has been the most common Ca amendment used for improving brine impacted soils. Flue gas desulfurization gypsum is available in North Dakota but is still a sparingly soluble amendment. The purpose of this research was to investigate the use of calcium acetate (Ca‐Ac) as an amendment for brine‐impacted soils as compared to gypsum. Ca‐Ac has a similar concentration of Ca compared to gypsum but is over 100 times more soluble than gypsum. This laboratory experiment will compare how varying levels of gypsum and Ca‐Ac can influence soil hydraulic conductivity, and chemical and physical properties when mixed with oilfield brine‐impacted soils.

Enhancing Dynamic Shear Resistance and Efficient Micro-Void Reduction of Expansive Soil Using Activated Nano-Desilicated Fly Ash

Excessive swelling and high compressibility of soil have posed countless challenges such as poor dynamic shear strength for engineers dealing with cyclic loading in pavement structure. To address this challenge, the durability and mechanical properties of the investigated subgrade were treated with 10%, 20%, and 30% of activated nano-disilicate fly ash (NDFA) to the dry mass of the subgrade soil. A series of swelling pressure tests, One-dimensional compression tests, and dynamic triaxial (DT) tests were conducted on the samples fabricated using altered moisture content. The findings demonstrated that the swelling pressure and compressibility of the NDFA-treated specimens significantly decreased to an average of 15.3% and 18.4% respectively upon 20% inclusion of NDFA beyond which the swelling stress and compressibility values further decreased signifying the impact of NDFA on the expansive subgrade. The consolidation results also revealed that the treated soil’s consolidation parameters greatly decreased compared to the untreated soil with a high void ratio and compression index (Cc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{c}$$\\end{document}). The dynamic shear resistance of the subgrade soil increased by 36% upon the addition of 10% NDFA content compared to the untreated soil which portrayed a very low resistance against dynamic shear modulus (Gmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${G}_{max}$$\\end{document}) with a corresponding high damping ratio. The investigation revealed a strong correlation between Cc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{c}$$\\end{document} and dynamic shear modulus which is closely correlated to a coefficient determination of 0.99 due to the parameter’s dependency on porosity, particle shape, and stiffness.

Micronized PET as a green additive for lime stabilization of swelling soil

The use of Polyethylene Terephthalate (PET) as an additive in the stabilization of swelling soils is a sustainable option considering the increasing environmental pollution caused by improper disposal of plastic waste. Given the limited capacity of recycling programs, incorporating these materials in construction can be a viable solution. In the conducted study, compacted mixtures of soil-lime-PET were prepared at different dry unit weights (14, 15 and 16 kN/m³). Micronized PET was used with percentages of 5% and 10%, while hydrated lime was added at 0%, 2%, 4%, and 6%, both by dry mass. These mixtures were subjected to one-dimensional swelling tests. The results showed that the PET content, lime content, and porosity are significant factors influencing the behavior of compacted mixtures. The index porosity/volumetric lime content adjusted by an exponent (ƞ/(Liv)-0,26) can link the one-dimensional swelling behavior. The combination of both materials creates a sustainable solution for controlling soil swelling.

ANN-based swarm intelligence for predicting expansive soil swell pressure and compression strength

This research suggests a robust integration of artificial neural networks (ANN) for predicting swell pressure and the unconfined compression strength of expansive soils (PsUCS-ES). Four novel ANN-based models, namely ANN-PSO (i.e., particle swarm optimization), ANN-GWO (i.e., grey wolf optimization), ANN-SMA (i.e., slime mould algorithm) alongside ANN-MPA (i.e., marine predators’ algorithm) were deployed to assess the PsUCS-ES. The models were trained using the nine most influential parameters affecting PsUCS-ES, collected from a broader range of 145 published papers. The observed results were compared with the predictions made by the ANN-based metaheuristics models. The efficacy of all these formulated models was evaluated by utilizing mean absolute error (MAE), Nash–Sutcliffe (NS) efficiency, performance index ρ, regression coefficient (R2), root mean square error (RMSE), ratio of RMSE to standard deviation of actual observations (RSR), variance account for (VAF), Willmott’s index of agreement (WI), and weighted mean absolute percentage error (WMAPE). All the developed models for Ps-ES had an R significantly > 0.8 for the overall dataset. However, ANN-MPA excelled in yielding high R values for training dataset (TrD), testing dataset (TsD), and validation dataset (VdD). This model also exhibited the lowest MAE of 5.63%, 5.68%, and 5.48% for TrD, TsD, and VdD, respectively. The results of the UCS model’s performance revealed that R exceeded 0.9 in the TrD. However, R decreased for TsD and VdD. Also, the ANN-MPA model yielded higher R values (0.89, 0.93, and 0.94) and comparatively low MAE values (5.11%, 5.67, and 3.61%) in the case of PSO, GWO, and SMA, respectively. The UCS models witnessed an overfitting problem because the aforementioned R values of the metaheuristics were 0.62, 0.56, and 0.58 (TsD), respectively. On the contrary, no significant observation was recorded in the VdD of UCS models. All the ANN-base models were also tested using the a-20 index. For all the formulated models, maximum points were recorded to lie within ± 20% error. The results of sensitivity as well as monotonicity analyses depicted trending results that corroborate the existing literature. Therefore, it can be inferred that the recently built swarm-based ANN models, particularly ANN-MPA, can solve the complexities of tuning the hyperparameters of the ANN-predicted PsUCS-ES that can be replicated in practical scenarios of geoenvironmental engineering.

Analysis of Damage to Residential Buildings Due to Ground Movement Resulting from Man-Made Excavation in Soil Swelling Potential Zone

Analysis of Damage to Residential Buildings Due to Ground Movement Resulting from Man-Made Excavation in Soil Swelling Potential Zone

Effectiveness of lime kiln dust on swelling of subgrade expansive soil

BackgroundThe structure of flexible or rigid pavement built on expansive subgrade soil that has a volumetric change is vulnerable to many problems that might cause failure. Pavement and construction became more durable and economical by enhancing the quality of subgrade expansive soil. Solid waste recycling has become very popular recently as a means of attaining sustainable waste management, so using lime kiln dust (LKD), which is a by-product of quick lime production, to treat expansive soil in pavement subgrades. This research describes the effect of LKD on the chemical composition, strength, and swelling of high and low-plastic clay that were extracted from two sites. The minimum LKD required for treating expansive soils was determined by using the Eades and Grim pH test. From tests, it was found that the addition of LKD increased the shrinkage limit by a range (250–500)% and decreased the plasticity and swelling potential by between (50 and 100)% of expansive subgrade soils. The strength according to CBR, increased approximately by 150% for CL soil and 800% for CH soil.ResultsThe optimal percentage of LKD for CH soil is 6%, and for CL soil, it is 2%. The plastic limit increased by 50% for CH soil at 6% LKD. On the other hand, CL soil became non-plastic at 4% LKD. With an increase in the percentage of LKD, it led an the increase in the shrinkage limit by 500% in CH soil and 250% in CL soil. The free swell decreased by 50% in CH soil and 100% in CL soil. The swelling pressure decreased by 50% for two expansive soils. CBR increased by 800% in CH soil and by 150% in CL soil.ConclusionThis work found that the addition of LKD improves the physical, chemical, and mechanical properties of expansive subgrade soil.

Enhanced resistance to desiccation cracking of polymer–bentonite mixtures: an experimental investigation of underlying mechanisms

Polymers have been shown to enhance the resistance of swelling clay soils to desiccation cracking, a critical property in engineering applications, particularly in waste containment facilities. However, the microscopic and macroscopic mechanisms driving this improvement remain poorly understood. Additionally, the influence of different mixing methods on these mechanisms is not well-established. While dry mixing (DM) is more convenient for onsite implementation, wet mixing (WM) offers intercalation between clay and polymer, resulting in potentially more durable stabilization outcomes. In this paper, key properties related to desiccation cracking of a polymer–clay mixture were measured. The mixture was synthesized by amending Na-bentonite with sodium carboxymethyl cellulose (Na-CMC) using DM and WM. Soil water-retention characteristics curves (SWCC), swelling and shrinkage potential, tensile strength, and pore-size distribution by mercury intrusion porosimetry (MIP) were measured for both mixtures and untreated bentonite. Compared to pure bentonite, mixtures were found to have slightly reduced air-entry values, significantly lower swelling and shrinkage potentials, and higher tensile strengths. In all experiments, DM exhibited superior performance compared to WM. MIP analysis of the amended mixtures revealed a more porous structure compared to untreated bentonite.

Impact of Vetiver Plantation on Unsaturated Soil Behavior and Stability of Highway Slope

Due to cyclic wetting and drying, the hydro-mechanical behavior of unsaturated soil is impacted significantly. In order to assess the soil strength parameters, knowing the unsaturated behavior is important. Soil moisture content is an important parameter that can define the shear strength of the soil. Most of the highway slopes of Mississippi are built on highly expansive clay. During summer, the evaporation of moisture in the soil leads to shrinkage and the formation of desiccation cracks, while during rainfall, the soil swells due to the infiltration of water. In addition to this, the rainwater gets trapped in these cracks and creates perched conditions, leading to the increased moisture content and reduced shear strength of slope soil. The increased precipitation due to climate change is causing failure conditions on many highway slopes of Mississippi. Vetiver, a perennial grass, can be a transformative solution to reduce the highway slope failure challenges of highly plastic clay. The grass has deep and fibrous roots, which provide additional shear strength to the soil. The root can uptake a significant amount of water from the soil, keeping the moisture balance of the slope. The objective of the current study is to assess the changes in moisture contents of a highway slope in Mississippi after the Vetiver plantation. Monitoring equipment, such as rain gauges and moisture sensors, were installed to monitor the rainfall of the area and the moisture content of the soil. The data showed that the moisture content conditions were improved with the aging of the grass. The light detection and ranging (LiDAR) analysis was performed to validate the field data obtained from different sensors, and it was found that there was no significant slope movement after the Vetiver plantation. The study proves the performance of the Vetiver grass in improving the unsaturated soil behavior and stability of highway slopes built on highly expansive clay.

Assessing changes in geotechnical properties of soil caused by oil contaminants

Soil pollution seriously threatens the integrity of geotechnical soil properties, considerably altering physical and mechanical characteristics. Therefore, the geotechnical characteristics of contaminated soils should be studied. Samples used in this study were obtained from Peshawar, Khyber Pakhtunkhwa Province, Pakistan. Tests such as Atterberg limits, direct shear strength, sieving analysis, consolidation, and unconfined compression were conducted. The internal friction angle, cohesiveness, and shear strength of the soil decreased when oil pollution was introduced, probably owing to the lubricating effect of oil, which also causes a decrease in the dielectric constant. Surprisingly, in certain cases, bioremediation could reduce soil swelling, relieve pressure from swelling, and prevent soil settlement. Oil contamination resulted in decreased permeability and mechanical strength in the analyzed soil samples. Importantly, the effect of oil contamination on the shear strength parameters is not uniform and depends on the soil type. A thorough study is required because of the long-term consequences of oil contamination, particularly the long-term aging effects on geotechnical soil properties and behavior. Therefore, these results must be compared with those of the most recent tests. Furthermore, future research should consider the complex interplay between the functional groups inherent in soil solids and the injected contaminated oil.

Comparative analysis of swelling mitigation in marl and clay soils: natural plant fibers (Alfa, jute, sisal) vs. polypropylene fiber with lime-pozzolana cement utilizing proctor compaction

This study offers a comparative assessment of two methodologies for mitigating soil swelling in marl and clay soils. The methods under investigation include the use of natural plant fibers (Alfa, jute, sisal) and polypropylene fibers in combination with lime-pozzolana cement. Laboratory tests, including Proctor compaction tests, and swell potential assessments, were conducted to assess the effectiveness of each method. The findings reveal that both natural plant fibers and polypropylene fibers, when combined with lime-pozzolana cement, effectively reduce soil swelling. The study underscores the promise of eco-friendly natural plant fibers and the durability of polypropylene fibers as viable solutions for soil stabilization. Furthermore, incorporating lime-pozzolana cement enhances both methods performance, providing an additional layer of soil stability. This research contributes valuable insights to geotechnical engineering projects dealing with marl and clay soils. It aids in the selection of suitable soil stabilization techniques, considering project-specific needs and sustainability concerns. Ultimately, this study advances the field of geotechnical engineering by promoting environmentally conscious and resilient solutions to address soil swelling in clay and marl soils.

Computational Analysis of Hydro-Mechanical Interaction in Sponge City Infrastructure

Sponge cities are urban areas that absorb and use rainfall like a sponge, thereby reducing flood risk and replenishing groundwater. However, the water-mechanical interactions in these systems are still poorly understood. In this study, the computer simulation fluid dynamics (CFD) method and Fluent software were used to evaluate the influence of soil leakage on pavement structure under the background of sponge city, focusing on two different soil layers. The fluid-structure coupling was analyzed by computer, and the pore water pressure changed significantly when the coupling effect was considered by computer software. When the penetration rate is 0.01 cm/s, the growth of plastic zone of soil is the smallest. Due to the upward seepage force caused by soil swelling and lateral water barrier, the strain index of road displacement is increased by 15%. The corresponding conclusion is drawn, which has practical significance.

Evaluation of Locally Available Calcined Clay-Based Geopolymer for the Stabilization of Expansive Soils

Geopolymers (GPs) have been effectively used as an alternative to traditional calcium-based stabilizers for treating problematic expansive soils over the last decade. However, the high cost of precursors and limited availability of traditionally manufactured GPs pose significant challenges for commercial implementation. Utilizing locally available sources to manufacture GPs could address such limitations and promote sustainable development. A research study was designed and implemented to evaluate the efficacy of locally available calcined clay-based GP stabilizers to improve the performance of expansive soils and the results were compared with lime-treated and untreated soils. An array of laboratory studies was conducted using two natural clayey soils and two types of GPs to assess improvements in several engineering properties, including unconfined compressive strength before and after capillary soaking, resilient moduli, and moisture-induced strains. Supplemental microstructural studies using X-ray diffraction, optical microscopy, and scanning electron microscope imaging were conducted to identify the mineralogical changes and detect the precipitation of new reaction products. The engineering studies demonstrated that the application of GP significantly enhanced the strength, durability, and stiffness while reducing the swelling and shrinkage strains in the GP-treated soils. Microstructural analysis revealed that the precipitated GP gels effectively coated the soil particles and provided a uniformly bonded GP–soil matrix that enhanced the engineering performance. Overall, this study provides a comprehensive understanding with respect to the potential of using locally available calcined clay-based GPs as a sustainable and durable alternative in enhancing the engineering properties of expansive soils for the long-term performance of transportation infrastructures.

The Effect of Bacillus Pumilus on the Free Swell and Atterberg Limits of Black Cotton Soil for use in Road Subgrades

The study evaluated the potential utilisation of Bacillus pumilus (B. pumilus) induced calcite precipitate for the improvement of the engineering properties of black cotton soil in road construction which is an eco-friendly technique and forms part of what is referred to as green engineering. The effect of B. pumilus on the free swell and Atterberg limits of black cotton soil for use in road subgrades was studied using microbial induced calcite precipitation (MICP) method. Five stepped B. pumilus suspension density of 0, 1.5 x 108, 6.0 x 108, 1.2 x 109, 1.8 x 109 and 2.4 x 109 cells/ml, respectively, were utilized for the treated specimens, while only cementitious reagent acted as the control specimen. Three (3) mix ratios of % Bacteria suspension (B) - %Cementitious reagent (C) (i.e., 25B - 75C, 50B - 50C and 75B - 25C) were adopted. It was observed that free swell treated with 25B - 75C decreased from 70 % and 50 % for the natural and control specimens, respectively, to minimum value of 46 %, with increasing B. pumilus suspension density at 2.4 × 109 cells/ml. Atterberg limits results showed liquid limit values decreased from 53 % and 62 % for the natural and control samples, respectively, to 43 % for samples treated with 25B - 75C at B. pumilus suspension density of 2.4 x 109 cells/ml, while the plastic limit increased from 28.2 % for the control soil sample to 30 % for the 75B - 25C mix ratio at B. pumilus suspension density of 2.4 x 109 cells/ml. Tests results indicated a considerable improvement with 25B - 75C mix ratio at B. pumilus suspension density of 2.4 × 109 cells/ml which significantly reduced the free swell, while the Atterberg limits fell below Nigerian General Specifications requirements of not greater than 35% Liquid limit, 12% Plasticity index and 35% passing No.200 sieve for utilization as road subgrades. However, it could be used as a subgrade material in low-volume roads.

Evaluation of Post Tension Runway Plate as Retrofitting Simulated with Compression In-Plane Force in Numerical Approach

The swelling of soil can result from fluctuations in its moisture content, causing it to expand and contract. To mitigate this, structures in direct contact with the soil may require retrofitting. Post-tensioning is one such method that can enhance the stiffness of the structure without altering its properties, thereby helping to prevent damage from expansive soil. This research presents a novel methodology for the design of retrofitting runway pavements using post-tension plates, employing a numerical approach that considers various influencing factors. The methodology integrates the use of differential and Kerr foundation equations, employing the Levy method to ascertain the deflection of the plate structure. Soil parameters are derived from soil sampling and laboratory tests, while loads are determined based on prior research findings and governmental regulations. The findings of the study indicate that the thickness of the plate structure influences its deflection, as greater thickness results in increased stiffness within the structure. Increasing the thickness of the plate enhances stiffness and diminishes deflection. Regarding the direction of post-tensioning, employing tension in both directions proves most effective, resulting in a reduction of deflection by 22.11%. However, this model demands higher costs compared to others due to the increased requirement for tendon post-tensioning. As an alternative, aligning the direction of post-tensioning with the direction of load movement can lead to a reduction of 15.14% in plate deflection, while incurring lower costs compared to applying post-tensioning in both directions.

Effects of Potassium Solutions on Swell Potential of Mae Moh Expansive Soil

This paper presents a field experiment of using potassium solutions to reduce swelling of expansive soil in the area of Mae Moh District, Lampang Province, Thailand. Based on the fact that the difference between montmorillonite in expansive soil and illite in non-expansive soil is the silica-gibbcite structure of the former was bonded by water molecules but those structures of illite was bonded by potassium ions. Therefore, an assumption of this research was if the expansive soil were soaked in potassium solution, monmorillonite may change to illite, and the soil should no longer swell. The field experiment was conducted by drilling holes of approximately 2 meters depth. Then, released potassium hydroxide in the forms of solution and flakes as well as potassium chloride solution and potassium nitrate solution into the holes. Kept the holes fill with the solutions at all time. After 30 days and 90 days, drilled other holes nearby the solution-fill holes to collect soil samples for laboratory tests. The investigation revealed that only the 20% potassium hydroxide can reduce the swelling of Mae Moh expansive soil. The X-ray diffraction test discovered that after 30 days of applying KOH solution to the expansive soil stratum, only illite and muscovite but montmorillonite was found, then after 90 days only muscovite was found. Based on academic articles in chemistry and geology, the transformation of montmorillonite to illite, and transformation of illite to muscovite are possible. The study of using potassium hydroxide solution should be studied extensively because it will be useful for existing buildings.