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Background: Hyptis suaveolens (L.) Poit., native to the American tropics, is a pantropical annual plant and a major invasive species throughout India. It was anticipated that the availability of sunlight, coupled with its superior reproductive potential, persistent propagule bank, and dispersal ability, could lead to an increase in the growth and spread of this invader, thus potentially impeding herbaceous growth and diversity in non-native areas. Clarifying its ecological fitness and competitive performance will be useful to manage the spread of H. suaveolens in natural ecosystems that are facing a wide range of anthropogenic pressures. Methods: The present study is a three-tier experiment. In the first tier, a field study was conducted to assess the patterns of H. suaveolens abundance and herbaceous species diversity in response to light availability (sun, 842–1072 µmol m–2 s−1 and shade 253–341 µmol m–2 s−1) in the tropical dry deciduous ecosystems in the Vindhyan highlands, India. Furthermore, the impact of H. suaveolens abundance on the resident native and non-native species abundance and diversity was also studied. In the second tier, a randomized common garden experiment was conducted to understand the trait fitness of H. suaveolens in sun (940 µmol m–2 s−1) and shade (300 µmol m–2 s−1) conditions. In the third tier, a plant growth chamber experiment with high-light (940 µmol m–2 s−1) and low-light (300 µmol m–2 s−1) treatments was done to learn how H. suaveolens partitions its biomass between aboveground and belowground plant parts. Results: The field study indicated that the sunlit areas had a higher abundance of H. suaveolens and a lower diversity of resident herbaceous species than the shaded areas. The common garden experiment showed that sun-dwelling H. suaveolens individuals performed better in germinative, vegetative, eco-physiological, and reproductive traits than the shade-dwelling individuals. The growth chamber experiment exhibited that plants grown in high-light environment had greater seed germination, seedling recruitment, and aboveground biomass than those grown in low-light environment, whereas plants grown in low-light environment exhibited a higher root mass ratio than the high-light individuals. These results suggest that H. suaveolens individuals mask the understory vegetation owing to higher seedling recruitment, relative growth rate, photosynthetic performance, resource acquisition-allocation, and reproductive output in response to high-light conditions. Conclusions: The study concludes that light significantly controls the invasive population dynamics of H. suaveolens in dry deciduous forests. In high-light areas, H. suaveolens populations dominate the forest understory with suboptimal shade tolerance. In shade environment, H. suaveolens maintains a persistent soil seed bank along with 'Oskar individuals' that become active in response to high-light availability. The modus operandi is a 'sit and wait' strategy. The current study provides insights on prioritizing areas for H. suaveolens management that will potentially reduce the risk of biological invasions on the native species diversity of tropical regions. [ABSTRACT FROM AUTHOR]

This study delves into the necessity of surface treatment for pure nickel, with a primary focus on applying abrasive jet machining (AJM) in conjunction with a microcontact wear model to investigate the contact interface mechanisms involved in AJM. Experimental findings indicate that SiC particles primarily employ a cutting mechanism to remove asperity peaks on the workpiece surface. While this effectively removes these peaks, it may induce phenomena reminiscent of peen hardening and embedded hardening. Conversely, Al2O3 particles predominantly engage in a rolling extrusion mechanism, leading to noticeable hardening effects akin to peen hardening. The study utilizing microcontact theory derived a 90° erosion wear formula. The study demonstrates that SiC particles outperform Al2O3 particles. SiC particles significantly increase the curvature radius of surface peaks (ρ) and the real contact area (At) during equivalent grinding durations, substantially enhancing workpiece surface quality and service life. Furthermore, post-grinding, an expansion in the elastic deformation region at the particle-workpiece interface, attributed to workpiece surface hardening, mitigates wear, and stabilizes surface roughness. This comprehensive research thoroughly assesses the interfacial effects of different abrasives and grinding parameters, providing valuable insights for related fields. [ABSTRACT FROM AUTHOR]

Weak soils in marine environments present unique challenges for engineering endeavours due to its inherent characteristics and the dynamic nature of aquatic systems. In recent times, the use of nanomaterials has emerged as an effective method for strengthening such soft soils. The present study highlights the effect of nano-titanium dioxide on the strength, plasticity, and compressibility characteristics of marine soil treated with the optimal amount of lime (5%). The potential of nanoparticle in modifying the geotechnical behaviour was examined by adding 0.5%, 0.7%, 1%, and 1.2% of N-TiO2 per unit weight of dry soil. The unconfined compressive strength values of untreated, optimally lime-treated and optimally nano-treated soil specimens were 47 kPa, 467 kPa and 164 kPa, respectively. After 28 days curing period, the unconfined compressive strength of optimally lime-treated marine soil samples mixed with the optimal amount of 0.7% N-TiO2 showed a nine-fold increase to 491 kPa with respect to untreated soil. After the nanotreatment, the liquid limit reduced by 51% and the plasticity index lowered by 74%. This resulted in the improvement of the coefficient of consolidation from 0.001 to 0.004 cm2/s and a reduction in compression index value from 0.39 to 0.17. The microstructure of soil samples was examined using various techniques such as X-ray powder diffraction analysis, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis. The experimental observations indicate that marine soil treatment using N-TiO2 is a promising technique to improve the geotechnical behaviour of marine soil. [ABSTRACT FROM AUTHOR]

With global concerns on carbon emissions, there is increased need for various eco-friendly alternatives to conventional (cement and lime) additives used in ground improvement applications. This paper investigates the effect of three biopolymers—chitin, chitosan, and sodium carboxymethyl cellulose (NaCMC)—on the consistency limits of low plasticity organic silt soil. The theory of soil mechanics suggests that understanding the soil's plasticity nature is helpful in predicting strength and compressibility characteristics. The variation in the Casagrande liquid limit (LL), plastic limit (PL), plasticity index, and flow index of the soil are presented for 0.5–4% chitin and chitosan dosages, and 0.25–1% NaCMC dosage. For all three biopolymers, the consistency limits (more-so for LL than PL) increased with increasing dosage, with NaCMC addition producing a more dramatic effect compared to chitin and chitosan additions. The biopolymer additives formed 'bridge' connections between the soil particles, helping to improve strength properties. This bridging effect explains the significant increases in LL (being essentially a strength-based parameter) for biopolymer addition. A greater LL increase was observed for NaCMC addition since it is a gellable biopolymer with moisture retaining property. [ABSTRACT FROM AUTHOR]

The creep index plays an important role in calculating the long-term settlement of natural soft clays, so it is vital to determine the creep index quickly and accurately. However, the prediction accuracy of the existing creep index models is low. This study presents seven gene expression programming (GEP) models by using different combinations of the liquid limit wL, plasticity index Ip, void ratio e and clay content CI as input variables for the prediction of creep index. A total of 151 datasets were collected from the available literature for building and testing the GEP models. The proposed GEP models were compared with two machine learning (ML) models (i.e., back propagation neural network and random forest) and five conventional empirical models in terms of three statistical indicators. The research results showed that the prediction performances of the two proposed GEP models (i.e., with combinations C I - w L - e and C I - I p - w L - e as input, respectively) surpass those of the five conventional empirical models and two ML-based models, recommended for predicting the creep index of natural soft clays in engineering practice. [ABSTRACT FROM AUTHOR]

Bruguiera sexangula (Lour.) Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh. It grows well in moderate saline zones with full sunlight. This study presents leaf morphological plasticity in B. sexangula to saline zones. Leaves were sampled from different saline zones and various morphological traits were measured. The results exposed a wide deviations of leaf size parameters: leaf length varied 6.6–17.3 cm; width 2.7–7.8 cm; upper quarter width 2.2–6.5 cm; down quarter width 2.5–7.3 cm; and petiole length 0.17–1.43 cm. Leaf length was significantly larger in fresh water than in other salinity zones, whereas, leaf width, upper and lower leaf quarters were significantly larger in medium saline zone. Leaf shape parameters showed a large variation among saline zones. Leaf base angle was significantly larger in both medium and strong salinity zones. Tip angle was significantly greater in medium salinity zone. Leaf perimeter was significantly larger in fresh water but leaf area was significantly bigger in medium saline zone. Leaf index and specific leaf area were maximum in moderate saline zone. Plasticity index was the highest in moderate saline for almost all the parameters presented. The ordination (PCA) showed clusters of leaf samples although there were some overlap among them which suggested a salt-stress relationship among salinity zones. The results indicate that B. sexangula had a plasticity strategy on leaf morphological parameters to salinity in the Sundarbans. This study will provide basic information of leaf plasticity of this species among saline zones which will help for site selection of coastal planting and will also provide information for policy makers to take necessary steps for its conservation. [ABSTRACT FROM AUTHOR]

Withania somnifera (L.) Dunal. is a bushy evergreen plant that naturalizes dry and arid soils of subtropical regions across the world. It is widely recognized for therapeutic benefits and cultivated in rainfed areas for its drought tolerance. However, the purpose of the study is to investigate how W. somnifera adapts to different ecological conditions and the effects of these adaptations on the physio-biochemical properties of the plant. In this context, twelve populations of W. somnifera were collected from four diverse ecological ranges such as Cholistan desert (dryness ratio = 43.00–29.23, P = 101.4–149.2 mm), Thal desert (dryness ratio = 23.46–20.37, P = 185.9–213.1 mm), Rajanpur desert (Dryness ratio = 31.64–20.61, P = 137.8–211.6 mm) and Potohar Plateau (dryness ratio = 7.13–5.11, P = 611.5–850.4 mm) to explore the key anatomical and physiological modifications involved in ecological success of this species across heterogenic environmental conditions. Results showed that ionic contents, organic osmolytes, root and stem cellular area and trichome area substantially increased in Cholistan desert populations. We observed specific variations in Thal desert populations, including a higher shoot biomass and increased photosynthetic pigments, enlarged vascular bundles in stems and enlarged metaxylem and phloem areas in roots and leaves. Rajanpur desert populations were highly xeromorphic, with increased root biomass production, more leaves, thicker midribs and laminae, thicker epidermis and cortical region, sparse hairiness on leaf surfaces and deeply crypted stomata. Populations inhabiting the Potohar Plateau exhibited maximum plant height and shoot growth, large cortical cells in roots and leaves and numerous trichomes. Overall, these adaptive traits display W. somnifera resilience against environmental challenges, promising innovative applications in medicine and agriculture. [ABSTRACT FROM AUTHOR]

The influence of stress anisotropy (K) (i.e. the ratio between effective horizontal and vertical stresses) on the shear behaviour of soils has received significant attention in past studies, but how its influence depends on different values of the plasticity index (PI) has not been properly quantified. In this study, the results of a series of undrained triaxial tests on anisotropically consolidated soil at different values of K are reported, and together with past experimental data, the interactive roles of K and PI on the shear behaviour of soil are rigorously interpreted. The findings indicate that the peak shear strength increases with higher brittleness, whereas the peak excess pore pressure diminishes when the value of K decreases. Moreover, increasing the value of PI up to 35 tends to increase the peak shear strength, but beyond that the influence of PI seems marginal. Based on the findings of this study, empirical equations incorporating PI and K to estimate the undrained shear strength are proposed with acceptable accuracy. [ABSTRACT FROM AUTHOR]

The current article discusses the integrated geotechnical properties of Buraydah City's foundation beds for the purpose of determining their suitability for development projects, identify the engineering problems impacting the foundation beds as a consequence of the geotechnical behavior of the region under study, and recommend an appropriate solution. Furthermore, the stabilization of sand dunes with palm leaf powder (PLP) is suitable for development projects. Basic laboratory tests such as grain size, Atterberg's limits, free swelling test, chemical analysis, direct shear test, and unconfined compressive strength (UCS) was applied to thirty-nine bore holes (189 samples). X-ray diffraction (XRD) and microscopic analysis were also carried out. The ultimate soil bearing capacity (Qu) values of the examined samples range from 888 to 1412 kN/m2, and elastic settlement extends from 5.40 to 7.96 cm. The investigation results of fine-grained soil at foundation levels reveal that the liquid limit (LL) values range from 25.3 to 54.0%, plastic limit (PL) ranges from 19.2 to 28.0%, plasticity index (PI) ranges from 4.4 to 26.0%, and free swelling ranges from 35.0 to 58.0%. Also, the geotechnical properties of soil and rocks are integrated with Geographic Information System (GIS) to produce the geotechnical model. This model is utilized to recognize the geospatial distribution and categorize the geotechnical hazard in Buraydah City. The produced model illustrated that the geotechnical hazard area observed near from King Abdulaziz road south of the study area. Adding palm leaf powder induces the desired geotechnical properties in the soil of sand dunes. [ABSTRACT FROM AUTHOR]

An effort has been made to perform a detailed characterization of fine-grained soils considering the relative significance of plasticity index for liquefaction risk assessment of the alluvial soil along Indo-Gangetic River banks. To establish this, the author emphasizes the application of computational models in comparison to statistical or empirical approaches for investigation. The novel approach for evaluating the liquefaction risk of fine-grained deposits is performed using different computational models which were satisfactorily validated in the present study. These models consider SPT N-value and peak ground acceleration due to earthquakes along with the consideration of basic geotechnical properties of fine-grained soil. The comparative study suggests that the artificial neural network (ANN) model has achieved the best predictive accuracy as compared to the other four models and it can be used to facilitate the liquefaction risk assessment of fine-grained soil deposits. In addition, liquefaction hazard mapping for the concerned study area is presented based on the ANN model. The artificial intelligence (AI)-based liquefaction mapping technique has high potential as it radically advances risk prediction and preparedness against such seismic events. Also, the influence of some of the significant input parameters on liquefaction susceptibility has been elaborately discussed, in terms of the correlation matrix and relative significance plots. Liquid limit and plasticity index have achieved a relative weightage of 14% and 16%, respectively, for predicting factor of safety (FL), whereas the SPT N-value has the highest impact of 21%. It is also observed that when the magnitude of the earthquake (Mw) is increased substantially from 6 to 7, a severe reduction in FL of 27.04% was noted, whereas for increment in Mw from 7 to 8, 30.5% average reduction in FL was observed. The finding of this study makes a substantial contribution in the field of liquefaction studies using AI models for fine-grained soil with medium to high plasticity. [ABSTRACT FROM AUTHOR]

The shear modulus of a soil, G, shows a hyperbolic degradation curve relationship with increasing shear strain, γ. G is usually normalized against the small-strain modulus (Gmax) as G/Gmax vs γ (log). Factors that significantly influence G are shear strain amplitude, γ, soil plasticity index (PI) and effective pressure, σ′. Design curve charts of G/Gmax vs γ have been produced for seismic engineering purposes. Mathematical models have also been developed, using statistically analysed parameters to reflect the influence of γ, PI and σ′. Soil overconsolidation ratio (OCR) has a significantly lesser impact than the three mentioned factors. In this paper, mathematical fitting and shaping functions for PI and σ′ are developed to extend the shear modulus reduction model further. The requirement to calculate reference strain, γref, is removed, and only soil PI and σ′ are required. Cyclic triaxial experiments are conducted with reconstituted kaolin and bentonite in different mix proportions (to achieve varying PI) and at different effective stresses. The model equation matches well against both the established curves and experimental results and can facilitate preliminary prediction of shear stress–strain behaviour and Gmax with different cohesive soil types and at different depths below ground. [ABSTRACT FROM AUTHOR]

The creep behavior of cohesive soils is highly related to the plasticity index. To study the relationship between the creep and the plasticity index of soils, a creep model is proposed to apply to the creep behavior of several soils with different plasticity indexes, especially covering the very long 80 year monitoring data on-site and 3.5 year test data in the lab. For the same type of soil, the creep exponent does increase with the plasticity index; however, for different types of soils, there is not a clear trend between them. Besides, because the risk of creep failure depends on the creep exponent and the (normalized) stress–strain curve, it is not certain that the creep failure of one type of soil with a larger creep exponent will be quicker than another type of soil with a lower creep exponent. [ABSTRACT FROM AUTHOR]

Intrinsic soil properties, such as the Atterberg limits, are essential factors influencing the mechanical behaviour of the fine-grained soils. In this study, a series of long-term multiple-stage loading oedometer tests were performed on alluvial organic soils to investigate the creep behaviour. The plasticity ratios ranged from 0.4 to 0.63. The smaller value of the plasticity ratio Rp indicated higher soil plasticity. The results showed that the coefficient of secondary compression Cαe of alluvial organic soils was stress- and strain-rate-dependent. The coefficient of secondary compression change index m was derived using a double-logarithmic approach for a creep degradation and was related to the plasticity and clay percentage to fines. Based on the results, it was found that high plasticity soils exhibit slow creep degradation rate during one-dimensional straining under normally consolidated state. The results show that the higher soil plasticity expressed by the plasticity index, plasticity ratio and clay percentage to fines, smaller the coefficient of secondary compression change index. Moreover, the correlations among a soil plasticity properties and creep parameters for the alluvial soils have also been proposed. [ABSTRACT FROM AUTHOR]

This research paper is concerned with studying and evaluating the geoengineering characteristics and potential risks of the area under study with a view to safe urban expansion using GIS techniques. Different geotechnical laboratory tests such Atterberg limits, free swelling test, swell potential and pressure tests, chemical analysis, unconfined compressive strength (UCS) and rock quality designation (RQD) were performed on 28 boreholes (95 samples). Furthermore, X-ray diffraction was used to examine clay minerals. The results indicate that the UCS values range from 47 to 72.2 kg/cm2 and RQD from 21 to 45%. The free swell ratio ranges from 110 to 120%, and the plasticity index from 34 to 37%. In addition, GIS techniques have been utilized to produce the distribution layers of different geotechnical characteristics, then integrated to produce a geospatial urban model for delineating and defining safe and dangerous urban zones. This model is classified into four classes: low, moderate, high and very high hazard. Low and moderate hazards were detected in the major portion of the survey area. These portions are suitable for foundations at shallow depths. However, high to very high hazards were detected in the southeast portion of the study area. The reason for these areas is caused by the existence of heavily fractured limestone and highly swelling clay layers. This model would aid in the creation and discovery of the best areas of shallow base in the region under consideration. [ABSTRACT FROM AUTHOR]

This article presents a discussion of the paper by Akbay Arama et al. (2021) published in the Arabian Journal of Geosciences, Vol. 14, No. 7, Article 534. Using simple and multiple regression analyses, as well as soft computing artificial neural network (ANN) methods, Akbay Arama et al. (2021) investigated a large database comprising of 1253 Atterberg limits test results for high and very high plasticity clay (CH) soils that are dominant on the European side of Istanbul Province, Turkey. Stated objectives included querying the attainment of the plasticity index (PI) for these soils directly from only liquid limit (LL) test results. Based on regression analyses results, Akbay Arama et al. (2021) produced various correlations relating the PI to LL. Then, employing the Noe (2005) experimental PI–LL dataset, Akbay Arama et al. (2021) reported that their proposed correlations have superior predictive performance compared to those of eight previously reported PI–LL correlations selected (by them). The authors of the present discussion article are of the views that (i) the produced PI–LL correlations for the Istanbul CH soils may not be sufficiently reliable, (ii) it does not seem intuitive to compare the predictive capabilities of these proposed correlations against those previously reported in the literature and deduced for diverse groups of fine-grained soils sourced from geographically different regions, and (iii) since PI–LL correlations cannot definitively and consistently establish the water content corresponding to the experimental plastic–brittle transition point, the thread-rolling test for plastic limit (PL) determination (and hence by association for PI calculation) needs to be retained. Each of these views is elaborated in this article. [ABSTRACT FROM AUTHOR]

This article presents a discussion of the Arabian Journal of Geosciences, 394, Vol. 13, No. 11, which (among other things) proposed a new empirical correlation for the prediction of the plasticity index magnitude (and hence by association the plastic limit value) of fine-grained soils sampled from different depths in the Bakırköy District of Istanbul City. As inputs, the proposed correlation employs the activity index, along with defining parameters of the semi-logarithmic flow curve obtained from the Casagrande (percussion-cup) liquid limit test. This article presents the following: (i) a discussion of the relevant literature that was not covered in the original paper; (ii) clarifications on, and observations regarding, the general approach adopted in the original investigation; (iii) concerns over whether the proposed new empirical correlation can be meaningfully recalibrated for particular clay soil types specific to other regions around the world; and (iv) suggestions for improvement of the new empirical correlation by adopting a different set of input parameters. [ABSTRACT FROM AUTHOR]

Background: Geologic and geotechnical conditions of soils where Nanka and Ajali Formations outcropped in Anambra Basin, Southeastern Nigeria were investigated and accessed. This was done using detailed mapping and mechanical soil laboratory tests to unravel the genesis and continued expansion of gully erosion in the study areas. Results: Field study revealed that gully erosions are more pronounced in the study area with poor vegetation cover and a high degree of slope steepness. Grain size analysis revealed that the soils of the Nanka Formation have an average sand content value of 90.90% (sandy) and silt content value of 3.0% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 5.29%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.67 × 10–3 cm/s. The compaction test further revealed that the soils are loosely compacted. The soils for the Ajali Formation have an average sand content value of 95.10% (sandy) and silt content value of 1.43% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 2.70%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.70 × 10–3 cm/s. The compaction test revealed that the soils are loosely compacted. Conclusion: After field surveys and laboratory analyses, it was found that the gully erosions have been developing respectively on steep slopes and non-vegetated areas, and their genesis facilitated by the cohesionless and very permeable nature of the sandy formations. Following those key findings, it was proposed many practices (agronomic and engineering mainly) that can help mitigate the formations as well as the expansion of this very damaging hazard type. The potential implications of these gully erosion include damaging of buildings, residential houses, bridges, and roads, loss of farmland and vegetation, isolation of villages and towns, increased migration of inhabitants as well as degradation of agricultural fertile land. [ABSTRACT FROM AUTHOR]

The present paper presents different approaches which includes plasticity based criteria that helps in distinguish between liquefiable and non-liquefiable soils deposits having fine content. A brief review of the previous work has been mentioned to emphasise on the need of new parameters for liquefaction susceptibility of clayey soils. Clay content, liquid limit and water content are considered as key parameters that helps in liquefaction assessment. Several recommendations proposed by prominent researchers are described here to present wide range of plasticity index, liquid limit and other parameters that affects liquefaction behaviour of clayey soil significantly. But the differences in the range of plasticity index leads to confusion and misperception in determination of liquefaction susceptibility of fine grained soil. One of the high seismic zone site is analyzed using different approach which consider fine content of soil mass. It is found that for a better and proper segregation of the layers Bray and Sancio criteria may be adopted which uses plasticity as one of its input parameter and clearly differentiate site in between liquefiable, non-liquefiable and sites that may liquefy i.e. moderately liquefiable. This summarizes that plasticity is one of the significant criteria which draws a clear differentiating line between liquefiable and non-liquefiable soil deposits. [ABSTRACT FROM AUTHOR]

Samples of clay deposits in Obudu and its environs, southeastern Nigeria were evaluated to establish their potential for industrial use. Geochemical, mineralogical and geotechnical properties were employed in assessing the suitability of the clay deposits for potential industrial uses. Mineralogical analyses reveal kaolinite as the dominant clay mineral with quartz as the dominant non-clay mineral. The physical and geotechnical properties indicate that the hydrous and marginal expansive clays are fine-grained (75 μm > 2%), have low to medium plasticity (plasticity index 12.8–40.8%), low density (1.69 to 2.60 g/cm3) and low linear shrinkage (4–6%) on drying and firing. Geochemical analysis shows significant amounts (> 1.0 wt%) of SiO2, Al2O3, Fe2O3, MgO, CaO, and Na2O, and relatively low values (< 1.0 wt%) of K2O, FeO and TiO2. The clays meet the requirements for production of building bricks, roofing tiles, local pottery products and domestic ceramic wares other than ceramic white wares. However, these low grade clays will require a high degree of refining or beneficiation to remove the undesirable minerals to qualify for use in rubber, paper, paint and cosmetic industries. [ABSTRACT FROM AUTHOR]

In landfills, due to their low hydraulic conductivity, compacted clays (CC) are commonly used in multilayered structures as base liners and cover systems. Nevertheless, the hydraulic performances of the CC layer can be affected by temperature alterations. The CC barrier of cover systems is exposed to heating caused by waste degradation processes as well as by the air temperature fluctuations, including freezing and thawing and high temperatures. Exposition occurs especially during transitory configurations when the final cap is not completed with the protective soil layers. In the present work, four clayey soils of varying plasticity all suitable for landfill barriers according to the international standard requirements are tested with respect to their sensitivity to thermal stresses in terms of hydraulic conductivity changes. For each material, experimental tests are performed on compacted specimens comparing the values obtained soon after compaction with the ones obtained after exposition to freezing–thawing or drying processes, the latter caused by heating up to 60 °C. The results show that freezing–thawing is more detrimental than heating, since the first can increase the hydraulic conductivity by up to about 20 times, while the second by less than 10 times. The soils of medium plasticity are the most affected, while the ones with high plasticity show the ability to partially withstand the effects of the investigated thermal alterations. This behavior seems related to the water absorption capacity of the material. The results suggest that the optimum water content acquired from the Proctor Standard curve seems to be a suitable indicator of this partial recovery potential. [ABSTRACT FROM AUTHOR]

Consistency limits and soil plasticity are the basic parameters that represent the physical properties of fine-grained soils and provide important information about their engineering properties, such as the compressibility and shear strength. These parameters are the standard input for all soil investigation programs, so their correct definition and usage in the design have great importance. The liquid limit value, which is one of the parameters that determine the consistency properties of the soils, can be obtained by standardized mechanized experiments that minimize operator effects. Meanwhile, the plastic limit is calculated by an experiment that is not standardized and can be affected by the operator's experience. In this case, the important parameters that affect the soil behavior are obtained in a wide range of values, and the reliability of the results is debatable. Thus, this paper aims to develop a new correlation, where the plasticity index can be directly calculated based on the liquid limit obtained from standardized experiments. Thus, the effect of the operator on the plastic limit test is eliminated. The effect of mineralogy is also considered in the newly developed correlation in addition to previous studies in the literature. A comprehensive experimental program was applied to 301 high-plastic clay samples, which were taken from the Bakırköy region of Istanbul city (Turkey), and the results were used to obtain liquid limit values using the Casagrande cup method. [ABSTRACT FROM AUTHOR]

This study presents the effect of high plasticity on swell potential, swelling pressure and micro-structural characteristics of kaolinite-bentonite mixed clays. Five different mix ratios of kaolinite bentonite mixture of 100:0, 90:10, 75:25, 50:50 and 25:75 in % by weight of dry kaolinite were used. All five synthesised soils were then mixed with 0%, 5% and 8% of cement by weight of dry soil, cured for 28 days and subjected to the Atterberg limit, one-dimensional oedometer and scanning electron microscope test. The inclusion of 5% and 8% cement reduces the plasticity index of the treated soils as the percentage of bentonite increases. The effects on plasticity of treatment with 5% and 8% cement after a 28-day curing period was evaluated, and the results show that reduction in plasticity index resulted in decreased swell potential and swelling pressure of the kaolinite-bentonite mixed clays. The results of microstructural analysis of 5% cement-treated soils show formation of flocculated fabric and cementation of soil particles, and filling with cementitious compounds of the voids of flocculated fabric in the soil. The reduction in swell can be attributed to the resulting compacted and dense mass of treated soils due to cementation of soil particles and cation exchange. The complex swell behaviour of high-plasticity kaolinite-bentonite mix is explained using the one-dimensional oedometer test, by further experimental study and examination of the microstructure of treated soils. [ABSTRACT FROM AUTHOR]

Structural failure of buildings, roads, and other infrastructures has led to the loss of lives and monumental damage to the economy. In developing countries such as Nigeria, the failures are always attributed to the nature/type of soils in the area without considering other factors. With the increase in civil engineering constructions and the scramble for a limited portion of competent soils for such constructions, land, therefore, is becoming man's most priced commodity for agriculture, residential and industrial purposes. No works of such have been done in the area, it is, therefore, imperative to study the cause(s) to prevent further loss of lives and the negative effects of such on the economy. The study was carried out at Panyam and some surrounding localities on latitudes N9021′ and N9026′ and longitudes 9011′E and 9016′E an area of 72 km2. A total of forty samples were collected out of which twenty were selected for swelling potentials determination due to their cohesive nature within the 1.5 m depth. To characterize the swelling of the soils, inferential testing methods; direct method comprising Liquid Limit and Plasticity Index with values ranging from 30% – 70% and 10% – 27% respectively, and the indirect method (Free Swell Index, FSI) whose values range from 9.1% – 90% were used. Most of the soils analyzed based on the geotechnical standards were categorized relatively safe for civil infrastructure. Structural studies employed the direct measurements of surface structures to get the orientations of structures measured. Landsat image and Total Magnetic Intensity (TMI) map of the area was acquired from the Nigerian Geological Survey Agency (NGSA) for subsurface structural analysis. The RTP-TMI (reduce to pole) grid data of the area were processed to improve magnetic anomalies associated with edges of surface/near-surface geological structures using the MAGMAP two-dimensional fast fourier transform (2D-FFT) filters package in Oasis Montaj v7.2 software. Geophysical studies using aeromagnetic data at a near-surface depth of 40 m and fractures measured on the surface both revealed a major trend in the NNE – SSW. It was observed that structures constructed across the major trend suffered little to moderate damage while those constructed along the major fractures trend suffered severe damage. It was concluded that both soils and fractures played individual roles in the collapse of infrastructure in the area. [ABSTRACT FROM AUTHOR]

This study has been prepared as a reply to the discussion written by O'Kelly and Soltani (2021). [ABSTRACT FROM AUTHOR]

In this study, we utilize acceleration time histories data at eight KiK-net vertical arrays in Japan, recorded between January 2009 to June 2014, to analyze nonlinear seismic site response. Ground motion records provided by seismic vertical arrays allow estimation of in situ soil dynamic parameters. First, the shear modulus is computed from the shear wave velocity using seismic interferometry by deconvolution. Considering each record as an in situ cyclic test under seismic loading, the shear strain is computed as the velocity ratio between two sensors and the shear stress is assumed as a spatial function of accelerations. Using classic hyperbolic regression models, we quantitatively assess the relationships between the in situ soil dynamic parameters and the level of ground motion. We found nonlinearity starts at a quite low level of shear strain of 5 × 10−6–5 × 10−5, and becomes much more significant beyond a relatively high level of strain of 1 × 10−4. The threshold strains from ground motion observations are well consistent with those from previous laboratory tests. Finally, a parametric analysis is presented to discuss the influence of plasticity index on nonlinear soil behavior evaluations. It is concluded that the threshold acceleration of soil nonlinear behavior (generally ranging from 20 to 100 cm/s2) is mainly controlled by the stiffness and plasticity index, and the degree of soil nonlinear behavior is mainly controlled by the stiffness, plasticity index and the level of ground motion. [ABSTRACT FROM AUTHOR]

The estimated undrained shear strength (su) is often not a unique value because it can be evaluated by various test types and/or procedures, such as different failure modes, shear strain rates, and boundary conditions. This study explores (1) the relationship between reference undrained shear strength and in situ shear wave velocity in terms of the effective overburden stress, and (2) the independent relationships to evaluate the undrained shear strength with special consideration of different directional and polarization modes (VH, HV, HH shear waves), which has not been reported. This evaluation is done via a worldwide database compiled from 43 well-documented geotechnical test sites associated with soft ground. Finally, new correlation models are proposed to estimate the undrained shear strength based on the in situ shear wave velocity as well as the plasticity index or the overconsolidation ratio. The application of the shear wave velocity-undrained shear strength relation is illustrated through two independent case studies. The proposed relationships are expected to contribute to reasonable estimates of undrained shear strength as well as offer practical guidance on even extrapolation beyond the data that is available to geotechnical engineers. [ABSTRACT FROM AUTHOR]

Precipitation is a primary environmental factor in the semiarid grasslands of northern China. With increased concentrations of atmospheric greenhouse gases, precipitation regimes will change, and high-impact weather events may be more common. Currently, many ecophysiological indicators are known to reflect drought conditions, but these indicators vary greatly among species, and few studies focus on the applicability of these drought indicators under high CO conditions. In this study, five precipitation levels (− 30%, − 15%, control, + 15%, and + 30%) were used to simulate the effects of precipitation change on 18 ecophysiological characteristics in Stipa bungeana, including leaf area, plant height, leaf nitrogen (N), and chlorophyll content, among others. Two levels of CO concentration (ambient, 390 ppm; 550 ppm) were used to simulate the effects of elevated CO on these drought indicators. Using gray relational analysis and phenotypic plasticity analysis, we found that total leaf area or leaf number (morphology), leaf water potential or leaf water content (physiology), and aboveground biomass better reflected the water status of S. bungeana under ambient and elevated CO than the 13 other analyzed variables. The sensitivity of drought indicators changed under the elevated CO condition. By quantifying the relationship between precipitation and the five most sensitive indicators, we found that the thresholds of precipitation decreased under elevated CO concentration. These results will be useful for objective monitoring and assessment of the occurrence and development of drought events in S. bungeana grasslands. [ABSTRACT FROM AUTHOR]

Key message: We analyzed the shade tolerance of a tropical tree species based on the plasticity of 22 photosynthetic traits. Carpotroche brasiliensis leaves have characteristics of a shade-tolerant species, with low photosynthetic plasticity.Abstract: The objective of this study was to evaluate the photosynthetic plasticity of young Carpotroche brasiliensis plants in response to different light environments. This tropical tree species has some shade-tolerant traits, such as large and fleshy fruits, seeds with a high water content, and the ability for natural regeneration in the forest understory. In this way, we tested the hypothesis that, at the leaf scale, young C. brasiliensis plants have photosynthetic characteristics of shade-tolerant species, with low photosynthetic plasticity when grown under different light environments. For this, seedlings were subjected to four light treatments (60, 35, 25, and 15% full sunlight, corresponding to about 20.9, 11.9, 9.1, and 5.4 mol photons m−2 day−1, respectively) for 5 months. We evaluated the photosynthetic plasticity at the leaf scale through morphological and anatomical variables, as well as variables associated with the diffusive, photochemical, and biochemistry phases of photosynthesis. All key photosynthetic variables measured exhibited values of typical shaded leaves. The highest simplified relative distance plasticity index (RDPI) for light treatments was found for light compensation point (0.32), performance index (0.30), photochemical reflectance index (0.30), mesophyll conductance (0.27), dark respiration rate (0.27), and leaf area (0.19). The lowest RDPI for light treatments was found for the leaf anatomical variables (< 0.1). From the 22 photosynthesis-related variables analyzed, we conclude that, on a leaf scale, young C. brasiliensis plants exhibit characteristics of a typical shade-tolerant species. Based on our results, we can recommend the plantation of C. brasiliensis seedlings in forest enrichment programs or agroforestry systems, in which other tree species are present providing light environments below 35% full sunlight or about 10 mol photons m−2 day−1. [ABSTRACT FROM AUTHOR]

The quantity of water that might be attracted by soil particles (aggregates) depends on the physico-chemical properties of minerals comprising those particles (aggregates). The intensity of electro-magnetic fields surrounding fine particles controls the thickness of water films which are adsorbed by them. The new formula describing a nonlinear relationship between liquid limit and plasticity index values is presented in this paper. The correctness of the proposed formula was verified using laboratory data where liquid limit values were determined using only percussion (dynamic) or falling cone (static) methods. [ABSTRACT FROM AUTHOR]

Dynamic properties namely shear modulus (G) and damping (h) are input parameters for predicting the ground response of natural soil deposits. The dynamic properties of sands and clays are dependent on many factors such as void ratio, confining pressure, strain amplitude, morphology, and plasticity characteristics. Considerable research has been reported in the recent past by Seed and Idriss (Soil moduli and damping factors for dynamic response analysis, 1970), Hardin and Drnevich (J Soil Mech Found Div ASCE 98(7):667-692, 1972); Seed and Idriss (Ground motions and soil liquefaction during earthquakes. Earthquake Engineering Research Institute, Berkeley 1982), Vucetic and Dobry (J Geotech Eng Div ASCE 117(1):89-107, 1991) and many others on dynamic properties of sands and clays. The factors affecting the dynamic properties of sands and clays are well documented, but soils generally, occur as mixtures of sand, silt and clay in various proportions. There is very little effort made in understanding the dynamic behavior of sand-fines mixtures and therefore there is a need to investigate the dynamic properties of sand-fines mixtures. In the present paper, the results of the behavior of sand-fines mixtures under cyclic loads are discussed. The experimental program consisted of a series of cyclic triaxial shear tests conducted as per ASTM D 3999 (Standard Test Methods for Determination of the Modulus and Damping properties of soils Using the cyclic Triaxial Apparatus. American Society for Testing and Materials 1991) to investigate the strain dependent shear modulus and damping of sand-fines mixtures of different plasticity. Sand was obtained from the Sabarmati river and three types of locally available fines i.e. low-plastic, medium- plastic and bentonite fines were used. Fines content was varied from 15 to 60%. The effect of fines content, plasticity, and relative density on shear modulus and damping is reported. Shear modulus at 0.005% strain level correlates well with the plasticity index for sand-fines mixtures of low to medium plasticity i.e. 0 < IP < 40. [ABSTRACT FROM AUTHOR]

An estimation method for earthquake-induced pore water pressure and the post-earthquake settlement of soft clay was developed by focusing on its Atterberg's limits and the direction of cyclic shearing. To clarify the fundamental characteristics of clays with different Atterberg's limits under multi-directional cyclic shear, normally consolidated specimens of Kaolinite clay, Tokyo bay clay and Kitakyushu clay were subjected to cyclic simple shear under the undrained condition with various cyclic shear directions and shear strain amplitudes, followed by the dissipation of cyclic shear-induced pore water pressure. The effects of undrained cyclic shear on the pore water pressure accumulation and post-cyclic settlement were observed, and relationships with Atterberg's limits were then investigated. In conclusion, the pore water pressure accumulation and post-cyclic settlement induced by multi-directional cyclic shear increase considerably to a higher level compared with those generated by the uni-directional one and such a tendency is evident for clays with a wide range of Atterberg's limits. Comparisons of the results indicate that the soil with higher plasticity index shows the lower pore water pressure accumulation and post-cyclic settlement, irrespective of number of strain cycles and shear strain amplitude. Based on these results, a model for earthquake-induced pore water pressure and post-earthquake settlement was developed by incorporating the Atterberg's limits as a function of experimental constants and the practical applicability was confirmed. [ABSTRACT FROM AUTHOR]

The paper summarizes a compilation of existing cyclic experimental data on reconstituted and undisturbed specimens of low-plasticity fine-grained soils to assess liquefaction resistance. The authors normalized the data to reduce the effect of other relevant factors such as shear mode, density, effective confining stress and cyclic loading frequency. It is indicated that liquefaction resistance of the specimens reconstituted using slurry consolidation approach is lower than that of the undisturbed specimens. The liquefaction resistance for undisturbed specimens decreases with an increase in the plasticity index up to 4-5 and then increases with a further increase in plasticity index. A new correction factor K to estimate the effect of plasticity index on cyclic resistance ratio is proposed for design purposes and added into the framework of liquefaction evaluation of claylike fine-grained soils with PI of 7-18 (change to 5-18, if ML-CL) on the base of the approach of Boulanger and Idriss. Because the effect of plasticity index on liquefaction resistance is slight when the plasticity index is <7, it is suggested that the liquefaction evaluation of sandlike fine-grained soils with PI of 0-7 (changed to 0-5, if ML-CL) follows the framework of simplified procedures using SPT and CPT data. [ABSTRACT FROM AUTHOR]

Evaluation of laboratory compaction parameters, i.e., maximum dry unit weight $${(\gamma_{{\rm d}{\rm max}})}$$ and optimum moisture content (OMC) of a soil, is an essential task in controlling field compaction for all earthworks construction. Laboratory determination of compaction parameters requires considerable time and effort which can be saved through the use of empirical correlations during early stages of a project. In this paper, correlations between consistency limits, compactive effort (CE) and compaction parameters, i.e., $${\gamma_{{\rm d}{\rm max}}}$$ and OMC, for fine-grained soils have been proposed. In order to develop the correlations, 105 soil samples of fine-grained soils representing various classification groups were collected from different areas of Punjab province of Pakistan. Besides classification tests, standard and modified proctor compaction tests were performed on the selected samples. Based on the classification test results, the selected samples are classified as CH, CL, CL-ML, ML with gravel fraction in the range of 0-12 %, sand fraction from 2 to 48 % and silt clay fraction from 50 to 95 %. The laboratory standard and modified compaction tests on the selected samples indicate the $${\gamma_{{\rm d}{\rm max}}}$$ in the range of 15.8-19.7 kN/m with OMC varying from 9 to 19.5 %. Multiple regression analyses were performed on the experimental data, and correlations have been proposed to predict the compaction parameters ( $${\gamma_{{\rm d}{\rm max}}}$$ and OMC) in terms of LL, PI and CE. In order to validate the proposed equations, an independent data set of 37 samples was used for the validation purpose. The comparative results showed that the variation between experimental and predicted values of $${\gamma_{{\rm d}{\rm max}}}$$ is within ±2.5 % and that of the OMC (%) is within ±9.5 % at 95 % confidence interval. Based on the correlations developed, predictive curves corresponding to standard and modified proctor energy are proposed for quick estimation of $${\gamma_{{\rm d}{\rm max}}}$$ and OMC based on LL and PI without performing the laboratory compaction tests. [ABSTRACT FROM AUTHOR]

It is a well-known fact that water content has a significant effect on the engineering properties of fine-grained soils. There is a close relationship between consistency limits and geotechnical parameters of fine-grained soils. This experimental study was performed to investigate the effect of randomly distributed polypropylene fibers (PP) and some additive materials [e.g., Borogypsum (BG), Fly Ash (FA) and Cement (C)] on consistency limits and plasticity index of a fine-grained soil. The Taguchi method was applied to the experiments and standard L9 Orthogonal Array (OA) with four factors and three levels were chosen. A series of consistency limits were conducted on each specimen. 0-20% BG, 0-20% FA, 0-0.25% PP and 0-3% of C by total dry weight of mixture were used in the preparation of specimens. In the tests, distilled water (DW), DW + 0.05% Air-Entrainer (AE) and DW + 0.15% AE were used as mixture liquid. Experimental results showed that the most effective material for decreasing the liquid limit and plasticity index of the samples were fly ash, polypropylene fiber respectively. The plasticity index decreased with increasing of AE. The values of plasticity index for distilled water, distilled water + 0.05% air-entrainer and distilled water + 0.15% air-entrainer in optimum conditions were 16%, 14% and 8%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the results of permeability tests performed using different organic fluids and soil types in order to derive a model to predict soil permeability based on the soil water permeability values. The equation proposed by Nutting (Am Assoc Petrol Geol Bull 14:1337-1349, ), which uses the concept of intrinsic permeability, was extended in order to take into account the fluid and solid particle interactions. The properties of soil (plasticity index, $$I_\mathrm{P}$$ , water permeability, $$k_\mathrm{w}$$ and water saturation, $$S_\mathrm{rw}$$ ) and fluid (density, $$\rho $$ , viscosity, $$\mu $$ , and relative dielectric constant, $$\varepsilon _\mathrm{r}$$ ) were used in the model. The model results demonstrated good adherence to experimental values ( $$R^{2}= 0.914$$ ). An error of about 6.4 times for the predicted soil permeability values was obtained, considering a confidence interval of 90 %. Experimental results extracted from technical literature were used to validate the model, using the same fitting constants as the experimental dataset of the authors. The model was able to capture the variation in the experimental results, although more than 10 % of the experimental results are located outside the confidence interval. [ABSTRACT FROM AUTHOR]

The definition of active porosity given by B.N. Gumenskii is revised. The active porosity is taken to mean the bulk porosity less the pore space volume occupied by adsorbed water. The methods of calculating the active porosity discussed in the paper are based on finding the adsorbed-water volume at the maximal airdry moisture of soil and subtracting this value from the bulk porosity. The active porosity is shown to be important for assessing the reservoir and infiltration soil properties and a number of other characteristics used in soil mechanics. [ABSTRACT FROM AUTHOR]

The influence of hydrocyclone construction parameters on nonlinear viscoplastic fluid hydrodynamics was analyzed using numerical modeling. The influence of the cone angle of the hydrocyclone case conical part and a dimensionless flow-rate parameter on axial damping of the tangential velocity component and the fluid film thickness was established. The influence of the construction parameters on the separating capability of the hydrocyclone was analyzed preliminarily. A physical justification of the results was presented. [ABSTRACT FROM AUTHOR]

Phenotypic plasticity is often considered important for invasive plant success, yet relatively few studies have assessed plasticity in both native and invasive populations of the same species. We examined the plastic response to temperature for Bromus tectorum populations collected from similar shrub-steppe environments in the Republics of Armenia and Georgia, where it is native, and along an invasive front in California and Nevada. Plants were grown in growth chambers in either 'warm' (30/20 °C, day/night) or 'cold' (10/5 °C) conditions. Invasive populations exhibited greater adaptive plasticity than natives for freezing tolerance (as measured by chlorophyll a fluorescence), such that invasive populations grown in the cold treatment exhibited the highest tolerance. Invasive populations also exhibited more rapid seedling emergence in response to warm temperatures compared to native populations. The climatic conditions of population source locations were related to emergence timing for invasive populations and to freezing tolerance across all populations combined. Plasticity in growth-related traits such as biomass, allocation, leaf length, and photosynthesis did not differ between native and invasive populations. Rather, some growth-related traits were very plastic across all populations, which may help to dampen differences in biomass in contrasting environments. Thus, invasive populations were found to be particularly plastic for some important traits such as seedling emergence and freezing tolerance, but plasticity at the species level may also be an important factor in the invasive ability of B. tectorum. [ABSTRACT FROM AUTHOR]

Improvement and stabilization of soils are widely used as an alternative to substitute the lacking of suitable material on site. Soils may be stabilized to increase strength and durability or to prevent erosion and dust generation. The use of nontraditional chemical stabilizers in soil improvement is growing daily. A new stabilizing agent was developed to improve the mechanical performance and applicability of clayey soils. In this study a laboratory experiment is conducted to evaluate the effects of plasticity index and waterborne polymer on the Unconfined Compression Strength (UCS) of clayey soils. The laboratory tests include sieve analysis, hydrometer, Atterberg limits, modified compaction and unconfined compression tests. Three clayey soils with different plasticity indexes were mixed with various amounts of polymer (2, 3, 4 and 5%) and compacted at the optimum water content and maximum dry density. The unstabilized and stabilized samples were subjected to unconfined compression tests to determine their strength at different curing times. The results of the tests indicated that the waterborne polymer significantly improved the strength behavior of unsaturated clayey soils. Also, an increase in plasticity index causes a reduction in unconfined compression strength. [ABSTRACT FROM AUTHOR]

Under natural conditions the overlapping of multiple stressors may initiate coordinated ecophysiological responses in Mediterranean species. Seasonal plasticity may enable plants to better cope with adverse environmental conditions and/or resource variability. In this article, we study the seasonal responses of 12 woody species in two sites of differing water availability, in a Mediterranean-type climate. Plants were measured for water potential, photochemical efficiency, photosynthetic pigments and leaf proline content throughout the year. The results revealed that species presented different ecophysiological strategies, even when sharing the same area. In the xerophytic site, some species suffered severe water stress (−12 MPa and F/ F lower than 0.3), while others exhibited optimal values of F/ F and only moderate water stress. All the plants recovered after the first autumn rains. In the hygrophytic site, some sclerophyll species did not exhibit signs of water stress, but did suffer photoinhibition in clear winter days. A plasticity index was calculated to provide an integrated value of species plasticity. In summer, plasticity was higher in the xerophytic site, while in winter it was higher in the hygrophytic site. Ordination analysis of the physiological traits supports the traditional gradient of Mediterranean strategies from drought semideciduous to evergreen sclerophyll species, although spiny legume species formed an independent functional group. The functional responses of species clearly differ among plant communities according to the prevailing site stressors, but no unique pattern emerges. Species combine traits in broader strategies according to previous evolutionary story exhibiting a certain amount of trade among traits, each contributing to alleviate a part of the plant stress. [ABSTRACT FROM AUTHOR]

The effect of material properties and surface roughness on the contribution of asperities and sphere bulk displacements to the total displacement of a rough spherical contact is investigated. A dimensionless transition load, above which the contribution of the bulk displacement exceeds the contribution of the asperities displacement, is found as a function of the plasticity index and dimensionless critical interference of the sphere bulk. A criterion is proposed for evaluating the importance of surface roughness in calculating the displacement of a rough spherical contact. Some experimental results with a spherical micro-contact are presented to verify the model. [ABSTRACT FROM AUTHOR]

Shallow landslides occur frequently on the Aso volcanic mountains. The soil materials on the Aso volcanic mountains consist of tephra layers formed by volcanic activities. This study is aimed to specify the physical properties of soil that correlate with the sliding layer of a shallow landslide on the volcanic mountain area. Tephra layers consist of kuroboku and scoria layers and the differences between these layers were specified using the physical properties of soil methods. Results showed that the plasticity index and the fine fraction content can be used for estimating the sliding layer in the Aso volcanic area. [ABSTRACT FROM AUTHOR]