Clay Soil Research Articles

Rainfall Patterns and Groundwater Dynamics: Implications for Soil and Water Conservation in Kodihalli Sub-Watershed, Haveri District, Karnataka, India

The Kodihalli sub-watershed (4D4D2f) is lies between 14028’23.68”-14034’20.103” North latitudes and 75026’49.224”-75031’44.208” East longitudes and covers an area of about 4398.83 ha. with an average annual rainfall of 783.0 mm (2014-2021). The maximum rainfall of 439.0 mm is received from June to September, 226.0 mm from October to early December and the remaining 118.0 mm is received during the rest of the year. The number of rainy days (>2.5 mm) varied from 13-24 days per year. On an average, the number of rainy-day events likely to produce runoff (20 to 30 mm) are about 2 to 8 rainy days per year with moderate variation across the years. The Actual Evapotranspiration (AET) over the years 2014 - 2021 in the Kodihalli sub-watershed varied from 383.0 to 770.0 mm. During 2014 - 2021, the average annual AET (621.0 mm) was less than the average rainfall (783.0 mm). The average AET/P ratio between 2014-2021 was about 0.79 which is less than the sustainable limit of about 0.80. The soils of watershed viz., sandy clay loam (IR 10 mm/hr) and sandy clay (IR 14 mm/hr) resulted in more infiltration rate than clay (2 mm/hr) and clay loam soils (7 mm/hr). Soil infiltration during a rainstorm is closely related to a number of factors such as the intensity and kinetic energy of the rainfall, soil surface conditions and soil properties such as those related to aggregate stability. For effective soil and water conservation, maximum area of about 3769 ha (85.7%) requires graded bunding and 267 ha (6.06%) area requires contour bunding.

Clays as Micro-Electrodes in Environmental Detoxification

AbstractIn-situ reduction of contamination in soil and groundwater is an ongoing challenge that often requires a multi-pronged approach for effective and efficient clean-up. Spontaneous or assisted electrochemical reactions that break down certain pollutants held on clay surfaces can render natural clays a unique and powerful ally in environmental mitigation of contaminated soils. Application of a low-level DC electric field (mV/cm) has been shown to facilitate transformation of some compounds and ionic species through redox reactions in addition to transporting them through the pores in wet clay soils. Results from previous tests suggest that the natural electrochemical processes that promote pollutant sloughing or chemical breakdown can be enhanced for targeted treatment by applying low-level electric field to the contaminated soil with clay content. The central idea of this hypothesis is that clay, due to its surface charge and electrostatic interaction with adjacent pore fluid, acts as a “micro-electrode” through the diffused double layer (DDL) interactions when subjected to an external electric field. This hypothesis, proven viable, may unlock potential ability of natural clays to generate beneficial reactions for detoxification of contaminated sub-surfaces. Evidence from past laboratory experiments accompanied by a proposed electrical model of clay behaving as a micro-electrode are presented in this paper. The laboratory experiment results support the proposed electrical model.

Influence of parent rock on soil clay mineralogy and physicochemical properties: a case study from the O’Higgins region, central Chile

Influence of parent rock on soil clay mineralogy and physicochemical properties: a case study from the O’Higgins region, central Chile

Amending clayey and sandy soils with nano - bio phosphorous for regulating tomato growth, biochemical, and physiological characteristics

Phosphorus is a critical nutrient that significantly enhances tomato production, so maintaining an adequate level of phosphorus plays an essential role in enhancing the growth of tomato by being present in the soil. This study assessed the impact of soil texture and phosphorus content on tomato plant properties using a factorial, complete, randomized design with four replications. Treatments included clayey and sandy soils with varying phosphorus sources: non-phosphorus (P0), calcium phosphate (CaP1 and CaP2), and nano-hydroxyapatite (PN1 and PN2), where 1 indicates a concentration of 0.12 g and 2 indicates a concentration of 0.23 g per 5-kilogram pot of fertilizer. Results indicated that treatments significantly influenced yield parameters such as average fruit weight, juice content, antioxidant activity, and fruit volume. In the clayey soil, CaP2 treatment had a superior effect on yield, average fruit weight, and shoot fresh weight. In comparison with sandy conditions, CaP2 produced a 50% increase in fruit number, 29% increase in average fruit weight, and 91% increase in fruit yield. The treatments then impacted the shoot fresh weight and root length, while the phosphorus concentration appeared to be more dependent on soil type than on phosphorus sources. Similar to the CaP1 and CaP2 treatments, the PN1 treatment in clay soil also resulted in the highest fresh and dry weights of tomato shoots when compared with the control group. Generally, the findings from this study suggest that the use of CaP2 can serve as a reliable method to improve the growth, yield, and fruit quality of tomatoes, especially in clayey soil environments. However, nano-based phosphorous sources need to be tested more to see if they can improve tomato performance in a range of soil conditions. Also, further research should look into the long-term effects of phosphorous interventions on soil health and sustainability.

An enhanced electrokinetic system for remediation of Cu-polluted clay soils by integrating purging solutions and intermittent power

This study investigated the effectiveness and underlying mechanisms of purging solutions enhanced by intermittent power in improving electrokinetic (EK) restoration of clay soils even under high levels of heavy metals (HM). In so doing, the artificially contaminated specimens containing a wide range of copper (Cu) were prepared and then subjected to a series of EK tests with various electrolytes and electric regimes. Macro and micro scale examinations revealed that under the unenhanced EK condition (i.e., continuous current without agents), the formation of non-conducting solid phases and/or the clogged fabric in the samples with the high dosages (> 250 mg/kg) of HM could dramatically impede the metal separation from the soil. Hence, increasing the remediation time would not be very effective in facilitating the decontamination process. It was observed that the EDTA-ameliorated treatment accompanied by pentetic acid and acetic acid can mitigate the metal precipitation/encapsulation effects induced by EK actions, resulting in improved rate of HM removal. In this case; however, a high portion of these enhancers would be required to ensure the stable mobility of ions and to achieve successful recovery. Such a limitation has been shown to be overcome by incorporating pulsed power (PP) at an optimal frequency. In fact, as evidenced by SEM-EDX and XRD analyses, the integration of chemical agents with PP could simultaneously retain the solubilized Cu species in the soil mass and modify the matrix tortuosity (i.e., the establishment of well-linked pores), two features that have been found to play essential roles in providing for favorable activity of HM ions during the EK operation. The corresponding refinements in the binary system would cause an almost 8 folds increase in the removal efficiency and a shorter (up to 30 %) time of treatment compared to conventional EK.

Evaluating the Effectiveness of the Biodegradable Superabsorbent Polymer (Fasal Amrit) on Soil Hydrological Properties: A Laboratory Rainfall Simulation Study

Superabsorbent polymers (SAPs) are effective soil amendments that can control soil erosion by improving soil quality. However, many commercial SAPs face challenges including limited biodegradability, high costs, and adverse effects on soil hydrological properties, which can lead to increased water and soil loss. This study examined the potential of lower dosages of biodegradable SAPs to improve the hydrological properties of “Shimajiri-maji” (clay) soil. Three concentrations of biodegradable Fasal Amrit polymer (EFP) (P1: 0, P2: 3 g m−2, and P3: 6 g m−2) were evaluated under three simulated rainfall intensities (I1: 35; I2: 70 and I3: 110 mm h−1) and two gradients (7.5%, and 15%) during consecutive storms. The time to generate runoff, infiltration, runoff, soil loss, and water storage (WS) were quantified over one hour. The results show that runoff generation was delayed in EFP-treated soils compared to the control. Both polymer treatments enhanced infiltration (P2 > P3 > P1) and reduced runoff and soil loss (P2 < P3 < P1). Higher EFP rates improved water storage at surface depths (P3 > P2 > P1). EFP-treated soils exhibited lower interrill erodibility, suggesting greater resistance to soil erosion compared to the control. EFP treatments also significantly improved the soil’s physical properties (bulk density, porosity, organic matter, aggregate stability). EFPs can diminish runoff and soil loss as the EFP-treated plots exhibited greater aggregate stability than the control. It was concluded that low EFP concentrations can improve soil hydrological properties and mitigate soil erosion. Further investigations are needed to optimize the EFP concentrations for different soil types.

Effect of Water Content and Degree of Compaction of Clay Subgrade Soil on the Interface Shear Strength Using Geogrid

Pavement performance in clay soil roads can be enhanced with the help of the geogrid concept by increasing lateral confinement, bearing capacity, and overall rigidity of the pavement. Also, geogrid is useful in minimizing vertical and lateral pavement deformations. In this study, 65 tests are performed without and with two types of geogrid, and the aim behind it is to investigate the effect of the moisture content and degree of compaction of clay soil on the interface shear strength. The number of materials used to conduct this study, included subbase granular (type B), clay subgrade soil, the Biaxial and SS2 geogrid which is used as a reinforcing material. Testing the direct shear is conducted by a large-scale direct shear manufactured device contains an upper box with side lengths of (20×20×10) cm, and a lower box with side lengths of (20×25×10) cm. Results show that for all tests the normal applied stresses are 25, 50, 75 and 100 kPa, the shear stress displacement curves for all cases follow similar trends and they are affected by normal stress, density and water content of subgrade soil and type of geogrid. Also, it is obvious that the shear stress increases by increasing the normal applied stress and degree of compaction of clay subgrade soil reaching its maximum value at 95% degree of compaction while it decreases by increasing the water content of subgrade soil. The maximum value of shear strength is observed when water content is equal to 8% (dry side) and finally, the Biaxial geogrid BX1100 (G1) is more efficient in reinforcing clay-subbase interface as compared with SS2 geogrid (G2).

Impact of Rainfall and Soil Infiltration on Groundwater Dynamics of Yerekoppi-1 Micro-watershed, Haveri District, Karnataka, India

The amount of water infiltrating the soil surface directly affects the quantity of surface runoff and erosion, and the recharge of both soil and groundwater. Groundwater recharge is an informative indicator of the water located beneath the ground surface. It has a direct impact on renewable supplies of groundwater. In the present study on Impact of rainfall and soil infiltration rate was used for effect on the groundwater level of the Yerekoppi-1 micro watershed (Manakur sub-watershed) in Haveri district of Karnataka state. Average annual rainfall is 700.7 mm and mean potential evapotranspiration is 1541.8 mm. An area of about 888 ha (94.32 %) has clay texture at the surface and 53 ha (5.68%) area has contributing settlement. In Yerekoppi-1 micro- watershed, 38 borewells are there in the vicinity of major stream of the micro- watershed. The mean depth of groundwater levels in the micro- watershed were monitored at a monthly frequency during January-2023 to March-2024. It was found that the maximum average depth of bore wells are about 17.6 mbgl and lowest average depth of borewell about 8.8 mbgl. Soil infiltration rate was measured at upper, middle and lower reaches of the watershed area in the year 2023 and 2024. The majority of the area contributed clay soil. In all the areas of micro-watershed, infiltration rate for clay soil is less than 5 mm/hr. Infiltration rates for all the areas was 1.72- 4.78 mm/hr. Soil infiltration during a rainstorm is closely related to a number of factors such as the intensity and kinetic energy of the rainfall, soil surface conditions and soil properties such as those related to aggregate stability. The groundwater recharge may be improved by growing plantation crop for increasing infiltration rate, construction of percolation tanks and farm ponds in the lower most of the agricultural land.

The pivotal role of arbuscular mycorrhizal fungi in enhancing plant biomass and nutrient availability under drought stress conditions: A global meta-analysis

Drought is a serious threat to crop productivity and global food security. About 40 % of the worldwide land is considered arid dryland soil because of a lack of rainfall, high solar radiation, and temperature fluctuations. Though rhizobacteria, particularly mycorrhizal fungi (MF), assist plants in coping with drought stress, an intensive quantitative assessment of their effects on plant growth and nutrient availability is still limited. We systematically carried out a global meta-analysis using 122 peer-reviewed publications comprising 3534 observations to investigate the effects of MF on plant biomass (PB) and nutrient availability (nitrogen: N and phosphorus: P) under drought-stress conditions. The results show that the MF inoculation significantly increased mycorrhizal colonization (MC), N and P uptakes, and plant biomass (PB) at a C:N ratio > 15 by 2171.44 %, 23.74 %, 135.61 %, and 220.91 %, respectively. The MF species Claroideoglomus etunicatum and Glomus significantly influenced the MC, N, and PB concentrations by 2541.68 %, 40.35 %, and 110.85 %, respectively. Moreover, the concentrations of MC, N, and PB were considerably affected by the soil texture categories, with the maximum levels of 4940.04 %, 127.05 %, and 84.04 % found in sandy, clay, and clay loam soils, respectively. In addition, soil pH, crop types, soil textural class, and MF species were identified as vital pedologic factors affecting plant growth and nutrient availability during fungal inoculation. Overall, this meta-analysis addresses gaps in understanding the effects of MF inoculation on plant development and nutrient availability under drought stress.

Differences in Cytokine Expression at Baseline and in Response to Mineral Stimulation by Peripheral Blood Mononuclear Cells from Podoconiosis Cases and Healthy Control Individuals

Epidemiological, histological, and immunogenetic studies suggest that podoconiosis (a non-infectious tropical lymphoedema affecting approximately 4 million people globally) is an HLA class II-associated inflammatory condition that develops in response to an unknown trigger found in volcanic red clay soils. Silicate particles of the kaolinite and aluminum types have been identified in femoral lymph node biopsy samples from endemic area residents, suggesting a possible role in the pathogenesis of podoconiosis. We measured in vitro peripheral blood mononuclear cell cytokine responses (TNF-α, IL-1β, and IFN-γ) to stimulation with the minerals kaolinite, chlorite, and beryllium sulfate (all at 100 µM) using ELISA. Real time PCR was used to measure gene expression of signature cytokines in fresh whole blood, comparing podoconiosis patients and endemic healthy controls. Our results showed that the levels of TNF-α and IL-1β from in vitro cell cultures were significantly higher in unstimulated samples from patients compared to controls (p = 0.04 and p = 0.005, respectively). The minerals kaolinite and chlorite induced two and three-fold higher levels of IL-1β following 24 h of stimulation in healthy controls compared to patients, respectively. We did not find significant differences in mRNA expression of the cytokine genes assayed, though a slight fold increment in IL-1β and TGF-β was observed. In conclusion, our data suggest that the immune system is in a state of persistent activation in vivo in podoconiosis patients, and additional studies of immune regulation and exhaustion are needed to further characterize immune dysfunction in the pathogenesis of the disease. A better understanding of the underlying processes could lead to the development of a ‘biosignature’ detectable in the early reversible stages that could ultimately contribute to the elimination of this preventable, disabling, neglected tropical disease.

Soil liquefaction manifestations at Hatay Airport after the February 2023 Türkiye earthquake sequence

Hatay Airport was shaken by the Mw 7.8 and Mw 7.5 Pazarcık and Ekinözü-Elbistan Kahramanmaraş earthquake sequence on February 6, 2023. Two weeks after these events, Mw 6.3 Yayladağı-Hatay earthquake shook the site again. This paper presents the results of the reconnaissance assessment of soil liquefaction at the site, focusing on mostly three aspects: (a) the seismic response of the Hatay Airport, particularly the surface manifestations of seismic soil liquefaction in the form of soil ejecta; (b) the findings of site investigation studies performed before and after the seismic events, and (c) assessments for soil liquefaction susceptibility. Among the soil ejecta samples collected, three out of five are classified as clayey sand and fall within or near the boundary of the “further studies required” region on the susceptibility charts. The remaining two ejecta samples, composed of low and high-plasticity clay soils with PI values of 31 and 36% fall within the “not susceptible” region. The deviation from the current state of knowledge might be attributed to liquefaction-induced seepage eroding clayey soils to the ground surface or limitations in the current liquefaction susceptibility assessment methods for fine-grained soils, which may not accurately delineate the boundaries between susceptible and not-susceptible zones. Determining the most likely explanation requires additional site investigation studies, including CPT soundings, extending beyond the scope of this reconnaissance study. The documented case history and assessment results are expected to enhance the understanding of seismic soil liquefaction in fine-grained soils and contribute to the development of predictive models based on case histories for assessing liquefaction susceptibility and triggering.

Analisis Daya Dukung Tiang Pancang terhadap Pengaruh Review Design Jembatan Wailola Besar Bula, SBT

In the work to replace the Big Wailola Bridge, several problems were encountered, including changes in the height of the planned and actual abutments. The planned abutment height is 7.20 M high and the realized height is 8.80 M. However, the changes (Design Review) do not change the structure of the pile foundation. And also from the boring results at the location it is known that at a depth of 36 M the SPT only shows the number 32, namely clay soil so that the bearing strength of the pile is determined from the frictional resistance between the pile wall and the surrounding soil (Fraction pile).

Modified Surface Drip Irrigation and Hydraulic Barrier Impacts on Soil Moisture and Water Productivity for Tomatoes in a Greenhouse

Considerable amounts of irrigation water of vegetable crops grown in homogenous sandy soil profiles could be subjected to deep percolation water losses due to inappropriately designed surface or subsurface drip irrigation methods. This study aimed to investigate the combined influence of implementing clay soil layer in homogenous sandy soil profile of low-tech greenhouse ridges and using modified surface drip irrigation (M-DI) on soil moisture distribution and water productivity of tomatoes. In the greenhouse, a 7.5 cm thick clay soil layer was implemented 15 cm from the soil surface of each ridge as a hydraulic barrier. Three irrigation regimes (100%, 70% and 50% of ETo) were imposed with the M-DI on tomato plants and 100%ETo with surface drip irrigation (DI) as control. Regarding economic valuation, viability was preserved for the M-DI and DI methods. The outcome indicated that soil moisture spreads more horizontally than vertically on the sandy soil above the clay soil layer. The combined effect of the homogenous sandy soil profile amendment and full irrigation (100%ETo) with the M-DI irrigation method increased the tomato fruit yield by 64.5%. Furthermore, the combined influence enhanced water productivity by the M-DI to 54.7 kg/m3 compared to 32 kg/m3 by the DI. However, M-DI demonstrated dominance over DI regarding returns, yield, and profit. Economic-wise, the M-DI requires 50% less of the lateral pipelines needed by the DI in low-tech greenhouses. Adopting the M-DI with a hydraulic barrier can improve soil moisture, water productivity, yield, and returns for tomato crops in low-tech greenhouses under sandy soil conditions. Also, the M-DI with the hydraulic clay barriers was an economically viable investment compared to the DI without clay barriers for growing tomatoes in low-tech greenhouses.

Bearing Performance of a Helical Pile for Offshore Photovoltaic under Horizontal Cyclic Loading

For an offshore photovoltaic helical pile foundation, significant horizontal cyclic loading is imposed by wind and waves. To study a fixed offshore PV helical pile’s horizontal cyclic bearing performance, a numerical model of the helical pile under horizontal cyclic loading was established using an elastic–plastic boundary interface constitutive model of the clay soil. This model was compared with a monopile of the same diameter under similar conditions. The study examined the effects of horizontal cyclic loading amplitude, period, and vertical loads on the horizontal cyclic bearing performance. The results show that under horizontal monotonic loading, the bearing capacities of a helical pile and monopile in a serviceability limit state are quite similar. However, as the amplitude of horizontal cyclic loading increases, soil stiffness deteriorates significantly, leading to greater horizontal displacement accumulation for both types of piles. The helical pile’s bearing capacity under horizontal cyclic loadings is approximately 60% of that under monotonic loading. With shorter cyclic loading periods, horizontal displacement accumulates rapidly in the initial stage and stabilizes over a shorter duration. In contrast, longer cyclic loading periods lead to slower initial displacement accumulation, but the total accumulated displacement at stabilization is greater. When vertical loads are applied, the helical pile exhibits more stable horizontal cyclic bearing performance than the monopile.

Geotechnical Study of Oxidative Covering Layers for Sanitary Landfills

Objective: The aim of this study is to investigate the analysis of the geotechnical behavior of pure soil and mixtures of soil with composted product for use in landfill cover layers. Method: The methodology adopted for this research includes laboratory tests for the physical characterization and determination of the properties of the materials used for the oxidative cover layer. To prepare the oxidative layer, it was necessary to mix organic compost with clay soil. The soil was collected from a deposit located near the Muribeca Landfill in Pernambuco. Results and Discussion: The analyses performed allowed a positive assessment of the geotechnical capacity that the mixtures can provide under the condition of landfill cover layers. The mixtures had a small increase in the proportion of coarser granulometry, reducing the plasticity of the material with the addition of the compost, possibly increasing the permeability of the layer. Also, the addition of compost did not cause a great loss in the geotechnical load-bearing capacity of the material. Research Implications: The material studied has shown potential suitability for use in oxidative covering layers for landfills, proving to be a viable alternative for implementation in smaller municipalities with less purchasing power, effectively reducing the need for the use of clayey materials, without compromising the safety of operation and subsequent use of the landfill site. Originality/Value: One of the difficulties encountered by municipalities in the use of landfills is the search for materials suitable for the solution, especially in municipalities with less purchasing power or located in arid regions, where the use of conventional layers presents problems, with drying out and opening of fissures. The relevance and value of this research are evidenced by the viability of the association of clayey soils with organic compost for the preparation of oxidative covering layers, reducing the pollutant load of organic waste.

The influence of volcanic ash (VA) on the mechanical properties and freeze-thaw durability of lime kiln dust (LKD)-stabilized kaolin clayey soil

Improving soft clay soil's mechanical properties and durability has been the subject of intense research. In this context, traditional stabilizers such as cement and lime have been introduced as the most widely used materials. However, the utilization of these conventional additives poses several challenges due to recent global concerns regarding the reduction of greenhouse gas emissions. Therefore, international research is shifting toward using environmentally friendly soil-stabilizing waste materials. This study, for the first time, evaluates the stabilization of kaolin clay soil using lime kiln dust (LKD) as a high CaO content waste pozzolan and volcanic ash (VA) as a natural pozzolan with considerable SiO2 and Al2O3 contents. In general, the research aims to demonstrate the effective performance of these two inexpensive and environmentally friendly additives in improving the mechanical characteristics and durability of kaolin clay soil, thereby providing the essential groundwork for the practical application of this method in stabilizing soft clay soil. This study included preparing samples with LKD at 3%, 5%, 7%, and 10% of the dry weight of clay and replacing LKD with VA at 0%, 25%, 75%, and 100%. The specimens were cured for 3, 7, and 28 days. Following the curing process, the optimal sample was subjected to varying numbers of freeze-thaw (F-T) cycles. The samples were examined by conducting a series of standard compaction, unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) tests at different stages of adding stabilizers, as well as before and after exposure of F-T cycles. The findings revealed that adding LKD and VA increased the UCS by accelerating and improving the pozzolanic and hydration reactions. Also, the combination of LKD and VA in kaolin soil enhanced F-T durability, resulting in less strength deterioration even after 10 cycles, when compared to the untreated control sample. In particular, the optimal mixture containing 5% LKD and 25% VA replacement improved 11 times in UCS compared to untreated kaolin clay and showed a slight reduction of only 7% after 10 F-T cycles. Overall, the incorporation of LKD and VA enhanced the mechanical properties and F-T durability of kaolin clay soil, making it a low-cost, sustainable, and eco-friendly option for soil improvement.

Chemical Composition of Clay Soil Analysis and Potential Health Risks: Experimental Study in Tshwane District, Gauteng Province

The practise of geophagy is common amongst women of childbearing age from different geographic locations, including South Africa, regardless of their social and economic status such as their level of education, race, marital status, income or occupation. This study aimed to examine the women of childbearing age in Tshwane District, Gauteng Province, South Africa. An experimental study was conducted at the laboratory to examine the chemical composition of clay soil ingested by geophagic women of childbearing age. Thirty-nine clay soil samples were collected from study participants attending antenatal care services and family planning at public healthcare facilities of Tshwane District, Gauteng Province, and subjected to geochemical analysis. The concentrations of vanadium, manganese, chromium, and barium were detected in quantities exceeding 100 mg/kg in almost all samples. Cadmium, mercury and silver were detected in low concentrations below 1 mg/kg in all samples. The practice of geophagy amongst women of childbearing age has been reported to be associated with detrimental health outcomes and risks such as iron deficiency anaemia, constipation, shortness of breath, maternal and childhood mortalities and morbidities, neurological and central nervous system disorder, death, appendicitis, cancers, teratogenic risks, and ulcers. The chemical composition of clay soil eaten by geophagic women of childbearing age contains potentially harmful substances, thus the practise of geophagy is toxic and should be discouraged to protect public health.

A Strain-Controlled Finite Strain Model for CRD Consolidation of Saturated Clays Considering Non-Linear Compression and Permeability Relationships

Consolidation is the combined phenomenon of the compression and groundwater seepage of clay. Accurate evaluation of the consolidation characteristic is essential for the design, construction, and long-term stability of geotechnical structures. In this study, a strain-controlled non-linear finite strain model for constant rate-of-deformation (CRD) consolidation was developed for quickly and reliably predicting the consolidation behavior of clay soils. The model can account for any form of non-linear compression and permeability relationships, thus considering variations in the coefficient of consolidation. Being strain-controlled, it overcomes the limitations of stress-controlled models which require complex numerical iteration. The validity and accuracy of this model were verified through rigorous comparisons with both numerical simulations and experimental data. For normally consolidated soils, a non-linear e-lgσ′compression model was used instead of a linear compression model. For overconsolidated soils, the Harris function compression model was determined to be recommended to overcome the discontinuities in total stress and pore pressure caused by the traditional piecewise e-lgσ′ model. It was also found that determining the steady state of consolidation for normally consolidated soils should use the non-linear method, while the linear method is suggested to be adopted for overconsolidated soils.

Identification of plant soil water and soil aeration corequisites: A management tool

AbstractPlant‐available soil‐water and adequate soil aeration within the root zone are essential corequisites for successful plant growth. Characterization of these two requirements for plant growth is generally done by independent measurements of water and air phase properties and functions in soil, with limited emphasis on their combined effect. This study investigated soil‐water characteristic (SWC) measurements in vadose soil profiles (up to 117‐cm depth) in six pasture soils to examine the combined behavior of soil‐water and diffusion‐controlled aeration within the root zone. The soil moisture measurements were made over matric potentials ranging from −1 to −1500 kPa using tension table and pressure plate apparatus. The van Genuchten model was used to parameterize the measured SWC curve, while the Millington–Quick model was used to derive soil‐gas diffusivity from measured soil physical properties. Based on two simple indices, derived to represent plant‐available soil‐water and soil aeration status at a given moisture content, we propose an assessment matrix, which illustrates how a soil satisfies the corequisites for successful plant growth, as it drains to different matric potentials upon irrigation. Results show a pronounced effect of soil texture and, to a lesser extent, soil structure on satisfying these corequisites. With the aid of the assessment matrix, we observed that loam, sandy loam textures exhibited a good overall performance, while sand, clay loam, and clay soils struggled to meet these corequisites during drainage.

Dampak Penggunaan Abu Marmer terhadap Kuat Geser Tanah Lempung

Soil is an important part of the building structure because it has a function as a support for the building. Therefore, soil stability must be considered so that building construction is safe and durable. There are types of clay soils that have high plasticity values and low shear strength. Soils like this require stabilization with the addition of additives such as marble ash. The purpose of this study was to determine whether the addition of marble ash content has an optimal impact on improving the plasticity, density, and shear strength properties. The added material used was marble ash with a content of 3%, 6%, 9%, and 12% by weight of dry soil. The specimens were differentiated based on their curing age before being tested by triaxial. Based on the research results, it was found that the use of marble ash had the maximum impact on improving the plasticity properties and maximum density at an addition of 6%. This was followed by a significant increase in shear strength at the same addition. A good curing age for increasing the angle of internal friction in the soil was obtained at 14 days.