Search Results (643)

This study focused on exploring the utilization of a one-part geopolymer (OPG) as a sustainable alternative binder to ordinary Portland cement (OPC) in soil stabilization, offering significant environmental advantages. The unconfined compressive strength (UCS) was the key index for evaluating the efficacy of OPG in soil stabilization, traditionally demanding substantial resources in terms of cost and time. In this research, four distinct deep learning (DL) models (Artificial Neural Network [ANN], Backpropagation Neural Network [BPNN], Convolutional Neural Network [CNN], and Long Short-Term Memory [LSTM]) were employed to predict the UCS of OPG-stabilized soft clay, providing a more efficient and precise methodology. Among these models, CNN exhibited the highest performance (MAE = 0.022, R² = 0.9938), followed by LSTM (MAE = 0.0274, R² = 0.9924) and BPNN (MAE = 0.0272, R² = 0.9921). The Wasserstein Generative Adversarial Network (WGAN) was further utilized to generate additional synthetic samples for expanding the training dataset. The incorporation of the synthetic samples generated by WGAN models into the training set for the DL models led to improved performance. When the number of synthetic samples achieved 200, the WGAN-CNN model provided the most accurate results, with an R² value of 0.9978 and MAE value of 0.9978. Furthermore, to assess the reliability of the DL models and gain insights into the influence of input variables on the predicted outcomes, interpretable Machine Learning techniques, including a sensitivity analysis, Shapley Additive Explanation (SHAP), and 1D Partial Dependence Plot (PDP) were employed for analyzing and interpreting the CNN and WGAN-CNN models. This research illuminates new aspects of the application of DL models with training on real and synthetic data in evaluating the strength properties of the OPG-stabilized soil, contributing to saving time and cost. Full article

Although soil stabilization with cement and lime is widely used to overcome the low shear strength of soft clay, which can cause severe damage to the infrastructures founded on such soils, such binders have severe impacts on the environment in terms of increasing emissions of carbon dioxide and the consumption of energy. Therefore, it is necessary to investigate soil improvement using sustainable materials such as byproducts or natural resources as alternatives to conventional binders—cement and lime. In this study, the combination of cement kiln dust as a byproduct and zeolite was used to produce an alkali-activated matrix. The results showed that the strength increased from 124 kPa for the untreated clay to 572 kPa for clay treated with 30% activated stabilizer agent (activated cement kiln dust). Moreover, incorporating zeolite as a partial replacement of the activated cement kiln dust increased the strength drastically to 960 and 2530 kPa for zeolite ratios of 0.1 and 0.6, respectively, which then decreased sharply to 1167 and 800 kPa with further increasing zeolite/pr to 0.8 and 1.0, respectively. The soil that was improved with the activated stabilizer agents was tested under footings subjected to eccentric loading. The results of large-scale loading tests showed clear improvements in terms of increasing the bearing capacity and decreasing the tilt of the footings. Also, a reduction occurred due to the eccentricity decreasing as a result of increasing the thickness of the treated soil layer beneath the footing. Full article

In the context of efforts aimed at reducing carbon emissions, the utilization of recycled aggregate soil mixes for soil stabilization has garnered considerable interest. This study examines the mechanical properties of mixed soil samples, varying by dosage of a soft soil curing agent C, recycled aggregate R content, and curing duration. Mechanical evaluations were conducted using unconfined compressive strength tests (UCS), field emission scanning electron microscopy (FESEM), and laser diffraction particle size meter tests (PSD). The results indicate that the strength of the mixed soil samples first increases and then decreases with higher dosages of recycled aggregate, reaching optimal strength at a 20% dosage. Similarly, an increase in curing agent dosage enhances the strength, peaking at 20%. The maximum strength of the mixed soils is achieved at 28 days under various proportions. The introduction of the curing agent leads to the formation of a flocculent structure, as observed in FESEM, which contributes to the enhanced strength of the soil mixes. Specimens prepared with a combination of 20% R and 20% C, maintained at a constant moisture content of 20%, and cured for 28 days exhibit a balance between economic, environmental, and engineering performance. Full article

This study was conducted to verify the usefulness of the laser diffractometer method for determining the particle size distribution of selected organic soils from the Podkarpacie region in Poland. The soil selected for this research represented three main classification groups, namely, low-organic, medium-organic and high-organic soil, in accordance with the standard criterion. Particle size distribution was determined using two types of laser diffractometers: the Helos laser diffractometer manufactured by Sympatec GmbH (Clausthal-Zellerfeld, Germany) and the laser particle size analyzer Analysette 22 MicroTech plus manufactured by Fritsch GmbH (Idar-Oberstein, Germany). The standard mechanical and sedimentation methods, which are perfect for testing mineral soils, are not applicable to organic soils; therefore, a serious problem was found and examined. A reference method that could verify the test results obtained using the laser diffractometer methods was required. After analyzing the literature, the hydrometric (sedimentation) method was adopted as the reference method. Currently, there are no reliable and fully verified methods for testing soils with such a complex skeleton structure, and the resources, standards and guidelines concerning the issues discussed are extremely limited; therefore, new research methods are being sought to fill this gap, and this work is a step in this direction. The results of the conducted studies and analyses have shown that laser diffractometry methods can be useful for determining the particle size distribution of organic soils, but to a limited extent, depending mainly on the quantity of organic substances. The highest agreement was obtained by comparing the results of the sedimentation method with those obtained using the diffractometer analyzer Analysette 22 in the group of highly organic soils. Full article

Peat soil exhibits significant creep deformation, and its consolidation law differs from that of soft soil. This study examines the strain characteristics of peat soils during three stages of consolidation using indoor one-dimensional creep consolidation tests. The results showed that the rebound deformation after the primary consolidation stage and the secondary consolidation stage is equivalent to the deformation seen during the primary consolidation stage, about 1.003 times. However, once the deformation stabilizes, the rebound deformation decreases to 0.32–0.85 times that of the deformation observed during the primary consolidation stage. The elastic and time-independent plastic strains of the peat soil showed two-stage linear changes with ${\ln \mathsf{\sigma }}_{\mathrm{z}}^{\prime }$. When the load was greater than the pre-consolidation pressure, the deformation modulus increases by approximately 2.10 and 1.56 times, respectively. On this basis, this study, for the first time, defines the creep rate according to the strain rate in the tertiary consolidation stage in the strain versus the time curve (${\epsilon }_z~t$). Based on the timeline, a one-dimensional creep consolidation model is established that can accurately predict the strain during the consolidation of the peat soil foundation. The results reveal distinct strain behaviors during each stage and improve the theoretical basis for the study of creep. Full article

Marine soft clay is widely distributed in coastal areas. Aiming at the characteristics of low strength and stress level of marine soft clay, the effects of normal stress, water content, and resting time on the pile–soil interface shear characteristics of marine soft clay–jacked piles were investigated using improved direct shear test equipment. On this basis, a practical interface shear strength prediction model considering the above factors is proposed. The test results show that the relationship between shear stress and shear displacement at the pile–soil interface can be divided into three stages—initial, transitional, and stable—and the relationship is in accordance with the hyperbolic model. Under the same water content and resting time, the interface peak shear stress increases linearly with the increase in normal stress. The interface peak shear displacement decreased with the increase in normal stress. Under different water content conditions, the peak shear stress decreases with increasing water content, while the corresponding peak shear displacement increases. The internal friction angle and adhesion at the pile–soil interface decreased rapidly and exponentially with increasing water content of the soil around the pile. The interfacial adhesion varies in the range of 1.07–13.76 kPa and the internal friction angle in the range of 1.8–6.1°. The change in water content when the water content of marine soft clay is less than the liquid limit has a great influence on the interface shear strength. The peak shear stress increases with increasing resting time, while the corresponding peak shear displacement decreases for different resting times. The Internal friction angle and adhesion at the pile–soil interface increases exponentially with the resting time. Interfacial adhesion changes in the range of 1.8–4.9 kP, and the internal friction angle is 2.8–4.7°. The strength of the pile–soil interface grows with the advancement of the resting time, and the bearing performance of the jacked pile is improved, with the most significant effect in 14 days. Based on multiple linear regression analyses, the effects of normal stress and water content on interfacial shear strength are comparable and the effect of normal stress on the shear strength is more significant compared with the resting time. The test results provide valuable reference for the design and construction of jacked piles in marine soft ground. Full article

The general lack of knowledge on the conditions of Western Siberia (Omsk region) and the taxonomic diversity of zonal soils determines the relevance of these studies. The research was carried out in order to study the effect of complex biologics on the taxonomic diversity of the fungal component of the microbiome of the rhizosphere of cereals and the phytosanitary condition of crops in the southern forest-steppe (meadow-chernozem soil) and subtaiga (gray forest soil) zones of the Omsk Irtysh region (Western Siberia). This work was carried out in 2022–2023, using laboratory studies in combination with field experiments and metagenomic and statistical analyses. The objects of research were varieties of cereals and grain forage crops of Omsk selection: soil microorganisms. The scheme of the experiment involved the study of the following options: varieties of cereals (factor A): spring soft wheat—Omsk 42, Omsk 44, Tarskaya 12; durum wheat—Omsk coral; barley—Omsk 101; oats—Siberian hercules; bacterial preparation for seed inoculation (factor B) without the drug—Mizorin and Flavobacterin. The sampling of the plant rhizosphere for metagenomic analysis was carried out during the earing phase (July). For the first time, the taxonomic composition of the fungal community was determined based on the analysis of amplicon libraries of fragments of ribosomal operons of ITS2 fungi during colonization of crop roots by nitrogen-fixing bacteria in various soil and climatic zones of the Omsk region. The fungal component of the microbiome was analyzed in two zones of the Omsk region (southern forest-steppe and subtaiga). The five dominant phyla of soil fungi were located in the following decreasing series: Ascomycota (about 70%) > Mortierellomycota (about 7%) > Basidiomycota (about 5%) > Mucoromycota (3%) > Chytridiomycota (1%). The five main genera of fungi inhabiting the rhizosphere of cereals are located in a decreasing row: Giberella (6.9%) > Mortierella (6.6%) > Chaetomium (4.8%) > Cladosporium (3.8%) > Rhizopus (3.3%). The predominantly positive effect of biologics of associative nitrogen fixation on the fungal community of the soil (rhizosphere) of experimental sites located in different soil and climatic zones has been established. During seed bacterization, the growth of saprotrophic fungal genera was noted in relation to the control variants Pseudogymnoascus, Chloridium, Clonostachys, Trihoderma, etc., and the fungicidal properties of bacterial strains introduced into the soil were actively manifested relative to phytopathogenic fungi of the genera Alternaria, Blumeria, Fusarium, etc. According to the results of determining the number of infectious structures of Rhizoctonia solani, it was found that the population of the soil with viable cells of this pathogen was 1–3 pcs/g (below the threshold of harmfulness, PV 20 pcs/g of soil), which indicates a favorable phytosanitary situation with respect to the pathogen. The fungicidal effect of the applied bacterial fertilizers on Rhizoctonia solani could not be detected. The number of Bipolaris sorokiniana varied depending on the drug used. In the conditions of the southern forest-steppe zone of the Omsk region (meadow-chernozem soil), the greatest fungicidal effect was noted in Flavobacterin application variants on wheat of the Omsk 42 variety, durum wheat of the Omsk coral variety, and barley; the decrease in conidia relative to the control was 73, 35, and 29%, respectively. In the subtaiga zone of the Omsk Irtysh region (gray forest soil), as in the southern forest-steppe zone, pre-sowing bacterization of seeds with Flavobacterin led to a decrease in Bipolaris sorokiniana in the rhizosphere of wheat of the Omsk 42 variety by 18%, and oats by 27%, to control. The use of the drug Mizorin in some variants of the experiment led to an insignificant decrease in the harmful fungus or had no effect at all. Full article

This study investigated the geotechnical and geophysical properties of the soil layers at the Missan combined-cycle power plant in Iraq. The data from 69 boreholes, including physical and chemical soil properties, were analyzed. The soil is primarily classified as silty clay with moderate to high plasticity, with some sandy layers. Since the Missan governorate is located in a seismically active region represented by the Iraq–Iran border, a study on the seismic properties of the site is also performed. Seismic downhole tests were conducted to determine wave velocities and dynamic moduli. The site was classified as soft clay soil according to FEMA and Eurocode 8 standards. Correlations for the physical and dynamic soil properties were evaluated. The correlations were executed via regression statistical analysis via Microsoft Excel software (2013). The results of the correlation equations and the coefficient of correlation R² show that the physical correlations were considered medium to good correlations, whereas the dynamic soil correlations were perfectly correlated such that the R² values were close to 1. This paper provides comprehensive data and soil property correlations, which can be valuable for future construction projects in the Missan area and similar geological formations. Full article

As an effective technology for the rapid treatment of soft-soil foundations, geosynthetic encased stone column (GESC) composite foundations are commonly used in various embankment engineerings, including those situated on sloped soft foundations. Nevertheless, there is still a scarcity of stability studies for sloped GESC composite foundations. Several 3D numerical models for sloped GESC composite foundations were established using an equivalent method. The influences of the area replacement ratio and the tensile strength of geosynthetic encasement on the stability were investigated. The results showed that the stability increased nonlinearly with the area replacement ratio, and there existed an optimal area replacement ratio (e.g., 24.56% in this study) to balance the safety and economic requirements. The stability increased linearly with the tensile strength of geosynthetic encasement at low tensile strength levels (lower than 105 kN/m in this study), and the impact was relatively limited compared with that of the area replacement ratio. In addition, the stability generally decreased nonlinearly as the foundation slope decreased, and high-angle (foundation slope close to 30°) sloped GESC composite foundations are recommended to be treated with multiple reinforcement techniques. The relationship between the minimum area replacement ratio and the foundation slope was further quantified by an exponential function, allowing for the determination of the area replacement ratio of various sloped GESC composite foundations and providing theoretical guidance for engineering practice. Full article

Jet grouted piles are widely used to reduce post-construction settlement of soft clay roadbeds. Nevertheless, it is easy to cause ground heave due to the jet grouted pile. According to the analytical method and numerical method, a sensitivity analysis of the factors affecting ground heave caused by a single jet grouted pile was performed. It is found that the influence of each parameter on ground heave is in the following order: grout pump pressure > embankment load > soil type (including the cohesion, friction angle, and Young’s modulus) > pile diameter > pile length. Considering the effect of the pump pressure on the ground heave is more significant, based on the analytical method of ground heave caused by a single jet grouted pile combined with the solution of small-deflection bending of a circular thin plate, the calculation method for the suggested limit grout pressure for construction under different embankment heights was established. Suggested values of theoretical grout pump pressure were given to prevent ground heave from harming the pavement of operating highways. This study provides some theoretical basis for the subsequent research on the jet grouted pile. Full article

Tick infestation poses an important challenge to livestock in Pakistan. Farm management practices and environmental variables can influence tick infestation prevalence in animals. To this end, a cross-sectional survey of 96 farms in four different geographical districts (24 farms from each district) was conducted in Punjab, Pakistan, between October 2021 and January 2022. An epidemiological questionnaire was designed focusing on farm management practices and their impact on tick infestations at these farms. Data were collected via in-person interviews. Regional and farm-specific variables’ associations were evaluated using Pearson’s chi-square test and Fischer’s exact test, respectively. A multivariable logistic regression model was used to identify significant risk factors. This study identified that using soft bedding materials, e.g., wheat straw, leaf litter or plain soil posed a significant risk of tick infestation. Additionally, the absence of quarantine measures, open sheds and inadequate drainage were found as contributing factors in univariable analysis. Higher tick prevalence in the hotter seasons highlighted the influence of Punjab’s extreme weather on tick infestation. Despite regular veterinary visits and the use of acaricidal drugs, the prevalence of tick infestation at these farms suggested potential drug resistance in the ticks. The study recommended establishing quarantine practices, improving farms’ drainage systems and bedding and using a combination of chemical and traditional remedies to tackle drug resistance in ticks. Education and awareness programs on tick-borne diseases and control measures are advocated to reduce the tick infestation burden on animals. Further research on longitudinal studies to better understand tick population dynamics and develop effective acaricides is encouraged. This called for collaborative control efforts among farmers, veterinarians and research institutions. Full article

In this paper, a multi-transmitting formula (MTF) was integrated into ANSYS software through secondary development, enabling dynamic finite element simulation of wave propagation in infinite domains. The numerical reliability and accuracy of the MTF were verified through a plane wave problem involving a homogeneous elastic half-space, as well as 3D scattering and source problems in a three-layered soil site. Additionally, a comparative analysis of various artificial boundaries was conducted to highlight the advantages of the MTF. Field observations of environmental vibrations caused by high-speed railway operations revealed localized amplification of vibrations along the depth direction at the Kunshan segment of the Beijing–Shanghai high-speed railway. Based on these observations, a series of numerical analyses were conducted using the customized ANSYS integrated with the MTF to investigate the underlying causes and mechanisms of this phenomenon, as well as the spatial variation characteristics of foundation vibrations induced by bridge vibrations during high-speed train operations. This study reveals the mechanism by which the combined effect of bridge piles and soft soil layers influences the depth variation in peak ground accelerations during site vibrations. It also demonstrates that the presence of bridge piers and pile foundations effectively reduces vibration intensity in the vicinity of the railway, playing a crucial role in mitigating vibrations induced by high-speed train operations. Full article

Ground settlement resulting from consolidation may lead to tilted buildings, cracks in the pavement, damage to underground utilities, etc. Therefore, it is crucial to understand the consolidation behaviors (including primary consolidation and secondary compression) of the soil of the subgrade. There is a large amount of soft clay deposited in Nanjing, located in the Yangtze River Basin. The consolidation behavior of Nanjing soft clay can significantly affect foundation design and the cost of construction. In this study, experimental measurements of the consolidation behavior of Nanjing soft clay were conducted, and parameters (such as pre-consolidation pressure, secondary consolidation index and secondary consolidation ratio) related to consolidation were assessed. The concept of simulated over-consolidation ratio (OCR_s) was proposed, and the close relationship between primary consolidation and secondary compression settlement and the OCR_s of Nanjing clay was investigated. Full article

In the past few decades, due to rising temperatures and changes in precipitation, the degree of drought in semi-arid areas has increased, leading to a large number of tree deaths and threatening the natural forests distributed in the semi-arid areas of North China. This article takes the forest ecosystem of Saihanwula Nature Reserve in the southern section of Greater Khingan Mountains in China’s semi-arid region as a research area and studies the distribution of downed dead wood and its impact on forest renewal in the area. We used the sample plot survey method, investigated the number of downed dead wood, decay class, dumping direction, existence form, and the number of regenerated seedlings in the sample plot, and calculated the density of regenerated seedlings in different plots. The renewal density is 4050 ± 824, 2950 ± 265, plants/ha, and 2625 ± 237 plants/ha, respectively, in the sample plots for Later-death plot, Mid-death plot, and Early-death plot. The average storage of downed dead wood in Saihanwula Nature Reserve is 58.51 ± 16.56 m³/ha. The distribution densities of downed dead wood are 50 ± 21, 806 ± 198, 189 ± 76, and 22 ± 5 plants/ha for decay classes II, III, IV, and V respectively. The main form of downed dead wood in the research area is “trunk base fracture”, accounting for 68.78% of the total number of downed dead wood. A large number of downed dead wood had serious negative effects, such as crushing and injuring the regeneration seedlings and other plants under the forest at the moment of dumping and for a long time after dumping. The crushed and injured rate is 5.3~7.8%, with downed dead wood accumulated in the forest from the early stage of downed dead wood. It had negative effects on the regeneration of seeds, seedlings, and young trees, such as obstructing and hiding the light from the soil surface and inhibiting the regeneration and growth of seedlings. However, after the trees were dumped, large gaps appeared in the forest, increasing the sunlight area on the soil surface. In the later stage of tree death, moderately high decayed downed dead wood changed the soil structure in terms of soil softness, water holding capacity, and nutrient content, thus promoting the growth of seedlings and young trees. Reasonably utilizing the relationship between downed dead wood and forest renewal can effectively promote the healthy development of forests. Full article

The Matsu Islands Tern Refuge comprises eight reefs located at a relay station on the East Asian bird migration route, and it attracts many transiting, wintering, or breeding birds to inhabit and live on the reefs every year. In order to understand the compositions of plant communities as a breeding habitat for seabirds, we investigated the plant communities of the eight reefs. A total of 130 plots of 10 × 10 square meters were established, from which we found 107 species of plants in 102 genera and 51 families. Among this, we found one critically endangered (CR) species, four vulnerable (VU) species, and three near-threatened (NT) species. The result of two-way indicator species analysis (TWINSPAN) and indicator value (IndVal) showed 130 samples were divided into 11 vegetation types; most of the vegetation types had significant indicator species. We also use the two-way to present the plot of detrended correspondence analysis (DCA) by vegetation types and reefs. Moreover, this result reveals that these samples were more clearly cluster divided by islands. Our results reveal that the compositions and characteristics of plant communities were related clearly to the environmental factors for each reef in the Matsu Islands Tern Refuge. Canonical correspondence analysis (CCA) indicated that species composition of vegetation yielded high correlation with soil property, especially with soil pH. In addition, we found that the traces of bird activity is relevant to the characteristics and structures of plant communities. We found that the plant communities comprising low-grass shrubs would provide relatively soft nesting materials and sheltering effects for eggs or hatchlings for terns. Compared to low-grass shrubs, the traits of high-grass shrubs would not be beneficial to nest for breeding of terns on the ground, and no nested trace was found in these plant communities. Full article