Clay Water Content Research Articles

Prediction of thermal conductivity of frozen soils from basic soil properties using ensemble learning methods

Thermal conductivity is one of the important properties required for understanding the frozen soils behavior. There are several models available in the literature for the prediction of thermal conductivity of frozen soils based on the proportions of unfrozen water, ice, gas, and soil particles. In this study, two ensemble learning methods-based models; namely, the Random Forest (RF) model and the Least Squares Boosting (LSB) model, are extended to estimate the thermal conductivity of frozen soils. These models utilize basic soil properties as input parameters that include water content, dry density, temperature, and fractions of gravel, sand, silt, and clay, can be measured easily, or determined. Additionally, seven widely used thermal conductivity models, referred to as the traditional models for frozen soils, were evaluated. Both the RF and LSB models, as well as the traditional models, were assessed using data of 823 tests derived from 43 soils with different textures that were gathered from the literature. The results highlight that the traditional models have their strengths and limitations in terms of their use for different types of soils. In contrast, the proposed ensemble learning methods-based models provide higher prediction accuracy compared to the traditional models and can be applied to all soil types and temperature ranges. Furthermore, estimation from the ensemble learning methods-based models can be used to provide probability of multi-dimensional analysis of frozen soils.

Study on the effect of ground stratification on heat transfer of vertical ground heat exchangers in lateritic clay areas

The potential effect of ground stratification on the efficiency of ground heat exchangers (GHEs) in lateritic clay regions remains unclear. Model experiments were conducted to investigate the effects of soil dry density, water content, and ground stratification on the heat exchange between GHEs and the surrounding lateritic clay. A 3D numerical model accounting for ground stratification was proposed and validated using experimental data. The model further examined the influence of soil moisture on the dynamic heat exchange process. The findings of the model experiments indicate that the heat from buried pipes increase soil temperature by 12.8 % when the initial water content of lateritic clay (with dry density of 1.1 g/cm3) rises from 5 % to 28 %. Raising the dry density from 1.1 to 1.3 g/cm3 at 28 % water content results in a 7.5 % temperature increase. The initial soil moisture and density have negligible effects on the temperature gradient within 18 cm of the geothermal pipes. The temperature increased faster in the sand layer than in the lateritic clay layer owing to the difference in thermal properties. The impact of heat produced by GHEs on the temperature field in homogeneous soil layers differs considerably from that in stratified soil layers. The 3D numerical model provided a good fit for the measured soil temperature in the stratified soil layer, including the soil temperature variation at the layered interface. The simulation results showed that for dry and saturated strata, the temperature of the lateritic clay around the GHEs increased with increasing initial stratum moisture. For unsaturated lateritic clay strata, because of the possible impacts of moisture and heat coupling migration, the temperature of the stratum around the GHEs first increased and subsequently decreased as the initial stratum moisture was enhanced.

Estimation of shale adsorption gas content based on machine learning algorithms

Shale gas is a clean and low-carbon natural gas resource. It mainly exists in both adsorbed and free states in pores and fractures. To accurately estimate the in-situ adsorption gas content (AGC), which is helpful in resource evaluation and development planning, methane isothermal adsorption data and geological parameters have been collected, such as total organic carbon (TOC) content, thermal maturity (Ro), siliceous mineral content (VQF), total clay content (VTC), water content (VWC), and temperature (T). Using machine learning (ML) methods, the in-situ AGC estimation models were constructed and optimized. Various geological factors affecting methane adsorption were evaluated, and an application was conducted in the Wufeng-Formation shale. The results reveal that the four ML models have higher accuracy in predicting Langmuir volume (VL) and Langmuir pressure (PL) than empirical formulas and linear regression models. Among the four ML models, the Random Forest Regression (RFR) and eXtreme Gradient Boosting Regression (XGBR) models perform the best, with R2 higher than 0.85. TOC and T are the main factors affecting methane adsorption, followed by Ro and VQF, while the importance of VTC and VWC is relatively low. According to different combinations of geological parameters, there are three schemes for ML model construction. Among them, scheme 1 based on all six geological parameters has the highest accuracy and is most beneficial to predicting AGC. Gradually reducing VWC, VTC, and VQF results in a slight decrease in accuracy, with R2 decreasing by at most about 6%, scheme 2 is suitable for rougher estimation of AGC. Further removal of T and Ro results in a significant decrease in accuracy, with R2 decreasing by up to 50% and MRE exceeding 30%, rendering scheme 3 unavailable for AGC prediction. The AGC of Wufeng-Longmaxi shale is successfully predicted based on XGBR model, with AGC mainly in 1.0 m3/ton-4.0 m3/ton. Overall, the ML models based on multiple geological parameters can simulate the real reservoir environment and achieve rapid and accurate estimation of in-situ AGC.

A rapid detection method for diesel content in diesel-contaminated soil based on dielectric measurement and oven-drying tests

Geophysical testing techniques have been successfully applied to identify light non-aqueous phase liquids in soils, but challenges remain in rapidly detecting contaminant content. Detection of contaminants in soil using geophysical testing techniques relies on sensors sensitive to electrical and electromagnetic parameter changes. In this study, the complex permittivity of silty clay contaminated with 0# diesel was measured using an open-ended coaxial probe at frequencies from 200–3000 MHz, and the four-phase dielectric mixing models were evaluated. The measurement results showed that the complex refractive index method (CRIM) model provided a better match with the real permittivity of the four-phase system between 500–3000 MHz with relative errors within an acceptable range of 4%. To eliminate the unknown variable in the CRIM model, an improved equation for the relationship between water content and diesel content of the watery diesel-contaminated silty clay was established by the oven-drying method. Thus, a method for the rapid quantitative detection of the diesel content in contaminated soil has been developed based on dielectric measurement and oven-drying tests. The relative error between the calculated and actual set diesel content for ten manually configured diesel-contaminated soil samples was within 10%, with a maximum error of 15.75%.

Sedimentation kinetics of kaolinitic and illitic clay: Impact of cation valence, ionic concentration, and water content

Investigating the sedimentation of clay in saline water was extensively studied because of its wide applications in engineering. This study investigated the impact of cation valence, ionic concentration, and water content on sedimentation behavior of kaolinitic and illitic clays through batch sedimentation tests for the comprehensive understanding of clay particle association and elapsed time for the transition of settling regimes from initial hindered settling to zone settling. The quantitative representation of observed settling curves was achieved using four fitted parameters in batch sedimentation model, which represented the shape of settling curves and the boundary of the initial hindered, zone, and consolidation settling regimes. In addition, the obtained settling velocity from the settling curves provided the fraction of clay particles and the size of clay flocs. The observed settling curves, trends of fitted parameters, and the estimated size of clay flocs shown in this study implied that the type of clay particle association (face-to-face aggregation or edge-to-face flocculation), settling velocity, final interface height, and boundary between initial hindered and zone settling are function of clay mineralogy, water content, cation valence, and ionic concentration.

Determining Liquid Limit and Plastic Limit of Clay Soils by Electrical Surface Conduction and Diffuse Double Layer Thickness

The aim of this study was to propose a new approach to determine the liquid limit and plastic limit of clay soils by considering electrical conductivity (EC) measurements. The proposed method included incorporating a new parameter, F, which is the ratio of the volumetric water contents of diffuse double layer (DDL) water and free water. In addition, the EC parameter, σ, was considered as the ratio of electrical surface conductivity and electrical conductivity of water. The changes in the thickness of DDL (χ) were also assessed to obtain corresponding equations to establish a connection with clay mineralogy, water content, and specific gravity in the final prediction. Three-dimensional surface analyses were conducted to find a correlation among F, σ, and χ to identify an appropriate method to predict liquid limit and plastic limit. The study was conducted with 39 different types of samples, and the outcomes from the EC approach were validated against the conventional methods. Overall, the coefficient of determination, R2 = 0.90, and Lin’s concordance correlation coefficient, (LCCC) = 0.91, were obtained for liquid limit prediction, whereas R2 = 0.64 and LCCC = 0.80 were obtained for plastic limit determination.

Mechanistic study of the effect of clay hydration swelling on CH4/CO2 competitive adsorption

The study on the hydration swelling mechanism of different types of shale clay minerals and the influence of water content on the adsorption characteristics of CH4/CO2 is of great significance for CO2 storage in shale reservoirs and enhanced shale gas recovery. Molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) were employed to establish different types of shale clay minerals (sodium montmorillonite, calcium montmorillonite, and illite). Hydration swelling simulations were performed at water contents ranging from 0.0 wt% to 20.7 wt%. Additionally, CH4 adsorption and CH4/CO2 competitive adsorption simulations were conducted at varying water densities. The effects of clay mineral type and water content on hydration swelling degree, gas adsorption capacity, and CO2/CH4 adsorption selectivity were analyzed. The simulation results indicate that variations in surface charge enrichment and interlayer cationic ionic radius account for the differences in hydration degree. Under the same water content, the hydration degree of the three clay minerals follows the order: sodium montmorillonite > illite > calcium montmorillonite. The gas adsorption capacity of clay minerals decreases with the increase of water content, and the greater the water content, the smaller the reduction range. With the increase of water content, the adsorption selectivity of CO2/CH4 first decreased and then increased, and the increasing range of different clay minerals was sodium montmorillonite > illite > Calcium montmorillonite. The research results of this paper have a certain reference value for the reasonable development of shale gas and the study of CO2 storage in shale.

Determining parameters of peat soil for finite-element analysis using the Cam Clay model

A practical procedure for determining soil parameters when analysing the deformation of peat by finite-element analysis (FEA) using the Cam Clay model is presented. FEA has not been frequently used to predict the deformation of peat soil, even though it can be a powerful prediction tool. The main reason for this is that a practical method for determining parameters has not been established. In this paper, the remarkable correlation between the soil parameters required for FEA using the Cam Clay model and the natural water content (wn) and ignition loss (Li) of peat and organic clay is presented. Then, based on this correlation, a flow chart for determining the soil parameters of peat and organic clay is proposed. Using this chart, it is possible to determine soil parameters directly from triaxial compression, oedometer and other detailed tests or to estimate them from wn, Li and other physical indexes. A trial embankment on peat soil in Hokkaido, Japan, was also created. FEA was performed on the trial embankment using the proposed procedure for determining the soil parameters. The results of the FEA corresponded to the measured settlement behaviour in the trial embankment with an accuracy in the range −4% to +8%. The FEA results also modelled the measured behaviour of pore water pressure and lateral and vertical displacements in the trial embankment very well.

Dynamic behavior of geopolymer stabilized kaolin clay under long-term cyclic loading

Geopolymer has emerged as an alternate cementitious material with a low carbon footprint, as they improve the engineering properties of soft soil without causing a detrimental effect on the environment. This study focuses on developing a combination of geopolymer materials that can fully replace the utilization of traditional binders to stabilize soft soil foundations in geotechnical engineering. Soft kaolin clay was stabilized using ground-granulated blast furnace slag (S) and dolomite (D) as a precursor (P) with combined content of 20% and NaOH: Na2SiO3 ratio of 25:75 as a liquid alkali activator (L) in the geopolymerization process. A series of Unconfined Compressive Strength (UCS) tests were conducted to analyze the influence of various parameters, such as the ratio of S and D, water content of kaolin clay, curing period, and L/P ratio, to select the optimum mix proportions based on strength improvement. This paper also discusses the behavior of geopolymer-stabilized kaolin clay under long-term cyclic loading in stress-controlled conditions. The effect of the S:D ratio, cyclic stress ratio (CSR), curing time, frequency, and confining pressure (CP) on the dynamic shear modulus (G), damping ratio (λ), and degradation index (G/Gmax) were analyzed. The results indicate that the S:D ratio of 16:4 with an L/P ratio of 1, NaOH: Na2SiO3 ratio of 25:75, and water content of liquid limit (LL) cured for 28 days gives the highest UCS value of 1.47 MPa. The initial dynamic shear modulus (Gmax) increases by 60% as the S:D ratio changes from 20:0 to 16:4. The cyclic performance of geopolymer-stabilized kaolin clay in terms of accumulative strain as a function of the number of loading cycles was also enhanced. The findings of the study provide guidance to a better understanding of the long-term dynamic behavior and application of geopolymer-stabilized kaolin clay as a greener approach to ground improvement.

Variability in soil properties influencing pigeonpea (Cajanus cajana L.) yield: a multivariate statistical analysis

Aims: The aim of the study was to reveal the variability in soil properties influencing pigeonpea (Cajanus cajana L.) seed yield under semi-arid rainfed condition. Methods: Soils were initially classified into series level and further these series were divided into soil-phase units. For two site years viz., 2018-19 and 2019-20, surface soil samples from each soil-phase unit were collected before sowing of pigeonpea and subsequently crop growth parameters at critical stages were recorded. Results: The principal component analysis with varimax rotation resulted in seven components for both the site years, having eigenvalues greater than one, explained more than 80% of the variability. The step wise linear regression analysis showed that the pigeonpea seed yield was linearly correlated with PC3 (p<0.01), PC4 (p<0.01) and PC7 (p<0.05) of soil properties with R2 = 0.679, during 2018-19. Whereas, during 2019-20, the seed yield was linearly correlated with PC1 (p<0.01), PC3 (p<0.01) and PC6 (p<0.05) with R2 = 0.677. In site year 1, the available P2O5, Fe, Zn, S, Cu, number of pods, surface soil moisture determined the yield. In site year 2, the available K2O, P2O5, Fe, Zn, S, clay, CEC and available water content determined the yield. All these variables together explain variability in yield.

Characterizing unfrozen water content of saline silty clay during freezing and thawing based on superposition of freezing point reduction

Soil freezing point and unfrozen water content are essential parameters for the design of an artificial ground freezing (AGF) system. Previous studies on AGF technology mainly focused on soils in non-saline areas and unfrozen water content characteristic of soils in saline areas with different initial water contents was rarely investigated. Through a series of freezing point and nuclear magnetic resonance (NMR) tests, this paper investigated the influences of salt type (i.e. NaCl and Na2SO4), salt content, and initial water content on the freezing point of saline soils during freezing, unfrozen water content and pore size distribution during freezing and thawing. NaCl saline soils showed a salt content-dependent freezing point, deviating from Na2SO4 saline soils. Hysteresis effects were evident in the phase transition point, unfrozen water content, and pore size distribution during the full freeze-thaw cycle. NaCl saline soils exhibited a gradual reduction in dominant pore size with decreasing temperature during freezing and thawing, while Na2SO4 saline soils was associated with wider range of pore size. The Clapeyron equation was adopted and modified to accurately predict the freezing point and unfrozen water content of saline soils with different salt and initial water contents under different temperatures with help of newly introduced correction coefficients (i.e. a, b, k3, k4, and kt). Furthermore, the accuracy of the existing model in predicting cumulative pore size distribution was improved with help of a newly correction coefficient (i.e. β) through an regression analysis.

Ash aggregation processes in a basaltic tuff ring (Songaksan, Jeju Island, Korea): Controls of diatreme conditions and transport processes

Aggregation of ash generated by explosive volcanic eruptions controls the dispersal and residence time of ash in the atmosphere and, therefore, the hazard to aviation. Ash aggregation is particularly common in hydromagmatic volcanoes produced by explosive magma-water interactions. Nevertheless, few studies have been done on this process because of the lower risk of volcanic hazards posed by these volcanoes in comparison to classical stratovolcanoes. Observations of the microscopic textures of the tuff samples from a Holocene tuff ring in Jeju Island, Korea, show that the ash particles occur mainly in the form of coated particles and ash lumps, which are either rich or poor in clay minerals derived from the substrate. The clay-rich aggregates formed in the diatreme by cohesive and capillary bonding of clay-rich and water-undersaturated debris. When the diatreme was filled with clay-poor and water-saturated debris, particles were ejected mainly without ash coats and aggregation. Once emitted from the diatreme, the aggregates and uncoated/solitary particles could be further aggregated together or accreted on larger particles by liquid bonding, producing clay-poor aggregates, multiple-coated particles, and composite ash lumps. The ash aggregation occurred mainly in co-surge ash clouds and ash plumes but not in pyroclastic surges, in which the time available for ash aggregation was too short (a few tens of seconds or less). This study demonstrates that the substrate characteristics and environmental factors that can influence the material properties of the diatreme fill, such as the clay mineral and water contents, are the prime controls of ash aggregation in hydromagmatic volcanoes.

修复多环芳烃污染地块的土壤氧化剂需求量

In order to better guide the dosage of chemical oxidants in the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil, KMnO₄, Na₂S₂O₈ and H₂O₂ were selected to study the kinetics, soil oxidant demand (SOD) and its influencing factors under four different plant areas in Chengdu, China. The results showed that KMnO₄ and H₂O₂ are rapidly consumed within 1 d. The consumption rate decreases rapidly after 1 d of the reaction, while the consumption rate of Na₂S₂O₈ is relatively stable. The reaction laws of the three oxidants are basically consistent with the first order kinetics. When the doses of KMnO₄, Na₂S₂O₈ and H₂O₂ are 1, 2,12 mmol/g, the SOD ranges of KMnO₄, Na₂S₂O₈, and H₂O₂ for each plot are 44.91～96.06, 40.91～52.86, and 371.47～406.25 g/kg, respectively. Statistical analysis show that the maximum demands of KMnO₄ and Na₂S₂O₈ are significantly correlated with soil organic matter content, soil clay and soil water content. Among them, soil organic matter content has the greatest effect on the soil oxidant demand of KMnO₄ and Na₂S₂O₈, with the contribution rates reaching 31.57% and 40.24%, respectively. According to the experimental results and considering the economic factors, the oxidants KMnO₄ and Na₂S₂O₈

Effect of installing columns from different solid waste materials on the soft clay bearing capacity

Soft clay deposits cause many problems due to low bearing capacity and high deformation. This paper presents the results of laboratory model tests for studying the improvement of soft clay-bearing capacity using two kinds of soil columns, the first is slag-cement dust columns and the second is bentonite column. Three columns from SCC (slag-cement dust columns) encased by Woven Geotextile are installed beneath a steel plate representing a footing. Four bentonite Columns (BC) encased with non-woven geotextile are installed around the steel plate at a distance of 1 B, where B is steel plate width. The research aims to assess the increase in the SCC length effect on clay-bearing capacity. A series of 4 experimental tests were performed. The results show that, the clay bearing capacity increased with the increase of column length because slag and bentonite can absorb the clay water content, leading to an increase clay shear strength. Floating columns gives better improvement than the end bearing columns. The slag partially replaced with cement dust is weak enough to transfer the total applied stress to a strong soil layer.

Sedimentary facies and clay mineralogy of the late Pleistocene Landsort Deep sediments, Baltic Sea — Implications for the Baltic Ice Lake development

ABSTRACT The Landsort Deep is the deepest part of the Baltic Sea and contains an excellent high-resolution late Pleistocene sediment record suitable to study the retreat history of the southern margin of the Fennoscandian Ice Sheet and the development of the ice-marginal Baltic Ice Lake (BIL) from ~13.5 to 10.5 ka BP. The studied cores are from the lithostratigraphic Units V and VI of Hole M0063C that were recovered during the Integrated Ocean Drilling Program (IODP) Expedition 347. The subdivision and interpretation of the studied BIL record are based on the identification of seven distinct sedimentary facies, grain size characteristics, detrital clay minerals, water and carbon content, and physical properties. The ice-rafted debris (IRD) in the lowermost part of Unit VI indicates a proximal glaciolacustrine environment. The onset of the Fennoscandian Ice Sheet deglaciation during the warm Bølling/Allerød interstadial caused a rise of the proglacial lake water level and the transition from ice-proximal (IRD-containing sediments) to ice-distal varved sediments (rhythmically laminated silty clays) detected within the middle part of Unit VI. This depositional unit of constant sedimentation was followed by the first drainage event of the BIL, which led to the deposition of a distinct clay-rich interval representing erosion and redeposition of the emerged lake bottom sediments. The reduced grain size of the overlying sediments is associated to the onset of cooler climate conditions and a possible ice sheet readvance during the Younger Dryas that resulted in a decrease of meltwater release and sediment availability. The higher sand content and kaolinite peak are associated to a rapid ice retreat and the release of abundant sediment laden meltwater plumes at the end of the Younger Dryas. The final drainage of the BIL enabled the erosion of coastal clay sediments, and the termination of the ice lake stage led to enhanced clay sedimentation to the Landsort Deep.

Generalized strength prediction equation for cement stabilized clayey soils

The role of clay minerals on the strength development of cement stabilized clays at different cement contents, water contents and curing times was studied in this research. Kaolin and sodium bentonite were used to represent non-swelling and high swelling soils respectively. The soils studied were mixtures of kaolin and bentonite at replacement ratios of 0, 25, 50, 75, and 100% of the dry weight of bentonite to have various swelling potentials. The water content of the soil samples was adjusted to the optimum water content (OWC) and to the liquidity index (LI) of 0.25–1.50, so as to simulate different initial soil phases. The macro- and micro-observation indicated that the clay mineral, water content and cement content were the predominant influence factors controlling the strength development of cement stabilized clays, at a particular curing time. For a particular clay mineral, the total soil water to cement content, s-w/c was found to be the prime parameter reflecting the effect from both water content and cement content on the strength development in cement stabilized clay. The generalized strength model can be represented in the form: qu = A/B(s-w/c) where qu is unconfined compression strength, and A and B are constant. The values of parameters A and B were found to be primarily controlled by the clay mineral, which was found to be described by plasticity index. The generalized strength model was validated using separated test data. This model will facilitate the engineering decision of selecting the water content and cement content to attain the target strengths of clayey soils at required curing time with minimum number of trials.

Gas-Bearing Property in Deep Marine Shale and Its Micro Controlling Factors: Evidence from the Lower Silurian Longmaxi Formation in Southern Sichuan, China

Abstract The gas content in shale reservoirs is often determined by the micro storage and sealing capacities of the reservoir. Deep shale reservoirs are in the high- or over-thermale maturity stage and have complex pore structure and connectivity, which are highly heterogeneous in vertical distribution. Research on the gas-bearing property of deep shale reservoirs is limited by these complex microscopic conditions. To analyze the gas-bearing characteristics of deep shale reservoirs, this work collected and summarized data on total organic carbon content, mineral composition, porosity, water saturation, and gas content measured on-site for the Longmaxi Formation in the Sichuan Basin in southern Sichuan, China. Then, experimental methods, such as X-ray photoelectron spectroscopy, transmission electron microscope, low-pressure N2 adsorption, spontaneous imbibition, and high-pressure methane adsorption, were used to analyze the micro storage and sealing capacities of the deep shale reservoirs. The results show that, different from shallow shale reservoirs (<3500 m), deep shale reservoirs have a higher graphitization degree and water saturation. An abundance of graphite structures often leads to weak resistance of organic matter to compression, deformation, or even collapse of pores in organic matter and severe damage to the gas storage space. However, a higher degree of graphitization can enhance the ability of the shale reservoirs to adsorb gas and self-sealing. The high water saturation in the reservoirs can interact with clay minerals and negatively affect the gas accumulation, storage, and transmission capacities of the shale reservoirs. However, the upper shale reservoirs with higher water saturation can seal the lower shale reservoirs, helping it preserve shale gas. Based on the vertical distribution of graphite structure, clay minerals contents, lithofacies, and water content in deep shale reservoirs, the essential microscopic conditions for deep shale reservoirs to have high gas content were proposed. This paper provides a detailed explanation and evaluation of deep shale’s storage and sealing capacities at the microscopic scale and can serve as a reference for further identifying the patterns for high-yield and rich shale gas reservoirs and improving deep shale gas exploration technologies.

Study of parameters influencing the compressive strength of Compressed Earth Blocks

This work aims to study four parameters that influence the compressive strength of compressed earth blocks (CEB): clay mineralogy, grain size, formatting pressure, and water content. Five soils with different mineralogical composition were used to study the first parameter. 12.5, 25, 40 and 60% of aggregates sized 0/2, 0/4 and 0/6.3 mm were added to the soil to study the second parameter. CEB were compacted at 100, 200 and 300 kN to study the third parameter. 3, 6 and 10% of water were used to study the fourth parameter. Test specimens were produced using a hydraulic press and characterized by compression. The characterization of the specimens shows that the compressive strength increases with the smectite content. Compressive strength does not always increase with changing particle size. Compressive strength increases with increasing formatting pressure, while increasing water content decreases compressive strength. This study also shows that the compressive strength of CEB is improved differently for each soil type.

The Liquid Limit as a Factor in Assessing the Improvement of Stabilized Cement-Based Highwater Content Clayey Sediments.

The purpose of this study was to assess the performance of high water content clayey sediments at different liquid limits as the clays are treated with cement-based solidifying materials. Three clay samples are obtained from different locations in the Kumamoto Reservoir. Two types of cement-based solidifying agents, namely, ordinary Portland cement and a cement–fly ash binder, were used. Using the initial water content of clay and the mixing amount of the solidifying agent as experimental variables, a cone penetration test was performed on the solidifying agent-stabilized clays to obtain the cone index (qc). The results showed that when the water content to cementitious content ratio (w/AW) was used as a parameter for evaluating the improvement of solidifying agent-stabilized clay, different forms of improvements were observed when different water and solidifying agent contents were used. This implied that the parameter w/AW was not suitable for evaluating the improvement of such clay. A new parameter, K, representing the content of solidifying agent, was introduced to account for the water content. For all sampled clays, the correlation coefficients for the K–ln qc relationship exceeded 0.9. Considering the effect of the liquid limit of the samples, the modified content of the solidifying agent (KL) was introduced to evaluate the cone index of the stabilized soils. It was discovered that the proposed equation unified the assessment of the improvement of the three samples of Kumamoto clayey sediments owing to the new parameter, KL.

Study on Crack Development in Red Clay from Guangxi Guilin with Different Clay Grain Content

In order to study the influence of different clay contents on the fractality of red clay, specimens having four different water contents were prepared. The cracking characteristics of the specimens were observed at 20 °C and 60 °C. Image J software was used to measure and calculate the crack area, crack ratio, crack length and width of each sample. The test results showed that the development of cracks in red clay could be divided into three stages: crack generation, crack development and crack stabilization. The clay particle content, temperature and water content have significant effects on crack development, and from the test analyses, it was determined that for construction in the Guilin area, it is necessary to pay attention to drainage protection.