This paper introduces a thermo-hydro-mechanical (THM) framework to model thaw consolidation in permafrost regions. By integrating internal energy degradation functions and a modified Cam-Clay model within a phase-field damage framework, the model focuses on simulating the simultaneous effects of phase change and particle rearrangement. The model integrates two distinct phase-field variables with the modified Cam-Clay plasticity framework. One phase-field variable monitors pore phase composition, while the other captures particle rearrangement. These variables are directly coupled to the constitutive model, providing critical data for updating the stress-strain relationship by accounting for particle rearrangement-induced softening and hardening effects due to volumetric deformation. The model converges to the modified Cam-Clay model when there is no phase change. This approach addresses a significant gap in existing models by capturing the associated microstructural evolution and plastic softening in thaw-sensitive soils. Validation efforts focus on experimental scenarios assessing both the mechanical impacts of thaw consolidation and the dynamics of phase transitions, particularly emphasizing latent heat effects. The results demonstrate the proposing model's capability of handling complex behaviors of permafrost under thaw conditions, confirming its potential for enhancing infrastructure resilience in cold regions.

A critical investigation of three constitutive models for clay by means of analyses of a sophisticated laboratory testing program and of centrifuge tests on monopiles in clay subjected to (cyclic) lateral loading is presented. Constitutive models of varying complexity, namely the basic Modified Cam Clay model, the hypoplastic model with Intergranular Strain (known as Clay hypoplasticity model) and the more recently proposed anisotropic visco-ISA model, are considered. From the simulations of the centrifuge tests with monotonic loading it is concluded that all three constitutive models give satisfactory results if a proper calibration of constitutive model parameters and proper initialisation of state variables is ensured. In the case of cyclic loading, the AVISA model is found to perform superior to the hypoplastic model with Intergranular Strain.

Potholes caused by road surface wear and sinkholes caused by soil subsidence can lead to accidents and vehicle damage. Monitoring their area and depth for timely repairs and road maintenance is crucial to ensure road safety. The camera vision device uses advanced imaging techniques to determine the shape and size of potholes, calculating their area and estimating volume based on the depth and contour information gathered. This study compared the results from the camera vision device with those obtained through traditional manual methods. The system measurements achieved a margin of error within 5 %, making it a reliable alternative for field applications. Additionally, this paper highlights the effectiveness of camera vision technology in modernizing road maintenance, thus facilitating a fast, accurate, and reliable method for assessing pothole damage. The findings indicate that implementing this technology can greatly enhance the management and repair of road infrastructure, lower costs, and improve safety.

BackgroundIn winter, tea plants are highly susceptible to low-temperature freezing damage. The rapid recovery of tea plant vigor in spring is crucial for tea yield and quality. Some studies have reported that Bacillus mucilaginosus could improve the stress resistance of plants. However, there were no reports on the effect of B. mucilaginosus on the recovery of tea plant vigor after low-temperature stress. This study firstly used different concentrations of B. mucilaginosus to spray tea leaves and used 16S rRNA high-throughput sequencing technology to study the impact of different treatments on tea leaf endophytic populations. Meanwhile, physiological indexes such as Soil and plant analyzer development values (SPAD), maximum photochemical quantum yield of PS II (Fv/Fm), and superoxide dismutase (SOD) were measured and analyzed in tea plant leaves of different treatments, and the correlation between them and the bacterial community was studied.ResultsMicrobial results showed that the diversity of leaf endophytic populations treated with different concentrations of Bacillus mucilaginosus (T1, T2, T3) was higher than that in control group (CK) leaves, and T2 treatment had the highest diversity. The dominant bacterial phyla of all samples were Proteobacteria, Actinobacteriota, Firmicutes, and Bacteroidota. At the phylum level, the relative abundance of Actinobacteriota, Firmicutes, and Bacteroidota in leaves treated with B. mucilaginosus was significantly higher than that in the control. At the genus level, the relative abundance of Paenibacillus, Nocardioides, and Marmoricola in leaves treated with B. mucilaginosus was significantly higher than that in the control. Different concentrations of B. mucilaginosus affected the distribution of leaf endophytic populations. At the level of bacterial function, abundant metabolic functional features were observed, including amino acid transport and metabolism, as well as energy production and conversion, indicating that bacterial metabolism in tea plant leaf samples tends to be vigorous. The treatment with B. mucilaginosus significantly increased the activity of antioxidant enzymes and osmolyte content, promoted the recovery of Fv/Fm in tea plants after low-temperature stress, and improved the resistance of tea leaves to low-temperature stress, thereby promoting recovery.ConclusionsThis study showed that B. mucilaginosus could significantly change the community structure of leaf endophytic populations, and increase antioxidant enzyme activity and osmolyte content in tea plants after low-temperature stress, promoting the rapid recovery of photosynthesis, and thereby benefiting the recovery of tea plant leaves. This study provided a theoretical basis for the application of B. mucilaginosus in practical production and also provided new ideas for the recovery of tea plants exposed to low-temperature stress.

Soft soils exhibit significant time-dependent effects during long-term deformation. To precisely describe the long-term behavior of soft soils, it is necessary to employ elastoplastic theory and rheology principles for investigating the stress-strain relationship of the soils. In this paper, a super-subloading modified Cam-clay model is initially derived. Subsequently, by introducing the Kelvin model to describe the creep behavior of soils, and combining it with the modified Cam-clay model, an overconsolidated structural viscoelastic-elastoplastic model is further presented. After converting the equation into matrix form and programming it in Fortran, the proposed model is implemented by ABAQUS. Then, the accuracy of the developed model and program is verified through comparison with existing literature and experimental results. Finally, parametric analysis is conducted to explore the impact of viscoelasticity, structure, and overconsolidation on the responses of soft soils.

Cylindrical cavity exhibits non-self-similarity during contraction process following expansion. Previous studies solve this problem with total strain approach and simple constitutive models, but the approach is not applicable when using an advanced constitutive model. This paper presents a semi-analytical solution for a cylindrical cavity undergoing expansion-contraction in undrained soils with auxiliary variable approach, incorporating the Modified Cam-Clay (MCC) model. The stress states around the cavity are formed by the superposition of initial and superimposed stress states. By treating superimposed effective stresses as self-similar, a semi-analytical solution is derived for solving the cavity expansion-contraction problem. The elastoplastic stress-strain relationship is formulated as a set of first-order differential equations, which can be solved as an initial value problem though Runge-Kutta (RK) method. Then the stress distribution around the cavity during expansion-contraction process can be determined. To validate the proposed approach, a series of well-conduced self-boring pressuremeter (SBP) tests are used to verify the proposed approach, which shows good agreements. Additionally, a FEM simulation incorporating the MCC model is performed, and the simulation results are presented to carry out parametric studies on soil parameters. A significant influence on the range of the plastic and reverse plastic zones is shown for overconsolidation ratio, while the in-situ coefficient of the earth pressure only quantitatively affects the stress distribution.

Cemented paste backfill (CPB) is a cemented void filling method gaining popularity over traditional hydraulic or rockfill methods. As mining depth increases, CPB-filled stopes are subjected to higher confining pressures. Due to the soil triaxial apparatus limitations, as the conventional method of triaxial testing on CPB, no confining pressures higher than 5 MPa can be applied to CPB over a range of curing time. This lack of data introduces uncertainty in predicting CPB behavior, potentially leading to an overestimation of the required strength. To address this, this study introduces a new testing method that allows for higher confinement beyond traditional limitations by modifying the Hoek triaxial cell to accommodate low-strength materials. This study then investigates the coupled influence of confining pressure and curing time (hydration) on CPB characteristics, specifically examining the impacts of different curing times and confining pressures on the mechanical and rheological properties of CPB. A total of 75 triaxial tests were conducted using 42 mm cylinder shape samples at five various curing times from 7 to 96 days, and applied at low and high confinement condition levels (0.5 to 30 MPa). The results reveal that hydration and confinement positively impact the CPB strength. The modified structured Cam-Clay model was selected to predict the behavior, and its yield surface was updated using the experimental results. The proposed yield model can be utilized to describe CPB material subjected to various curing and pressure conditions underground.

In order to consider the effect of fabric anisotropy in the analysis of geotechnical boundary value problems, this study proposes a modified model based on a fabric-based modified Cam-clay model, which can account for the anisotropic response of soil. The major modification of the original model aims to simplify the equations for numerical implementation by replacing the SMP strength criterion with the Lade's strength criterion. This model comprehensively considers the inherent anisotropy, induced anisotropy, and three-dimensional strength characteristics of soil. The model is first numerically implemented using the elastic trial-plastic correction method, and then it is encapsulated into the FLAC(3D )6.0 software, and tested through conventional triaxial, embankment loading, and tunnel excavation experiments. Numerical simulation results indicate that considering anisotropy and three-dimensional strength in geotechnical engineering analysis is necessary. By accounting for the interaction between microstructure and macroscopic anisotropy, the model can more accurately represent soil behavior, providing significant advantages for geotechnical analysis.

Snow, characterized as a unique granular and low-density material, exhibits intricate behavior influenced by the proximity to its melting point and its three-phase composition. This composition entails a structured ice skeleton surrounded by voids filled with air and spread with liquid water. Mechanically, snow experiences dynamic transformations, including bonding/degradation between its grains, significant inelastic deformations, and a distinct rate sensitivity. Given snow's varied structures and mechanical strengths in natural settings, a comprehensive constitutive model is necessary. Our study introduces a pioneering formulation grounded on the modified Cam-Clay model, extended to finite strains. This formulation is further enriched by an implicit gradient damage modeling, creating a synergistic blend that offers a detailed representation of snow behavior. The versatility of the framework is emphasized through the careful calibration of damage parameters. Such calibration allows the model to adeptly capture the effects of diverse strain rates, particularly at high magnitudes, highlighting its adaptability in replicating snow's unique mechanical responses across various conditions. Upon calibration against established experimental benchmarks, the model demonstrates a suitable alignment with observed behavior, underscoring its potential as a comprehensive tool for understanding and modeling snow behavior with precision and depth.

The significant uncertainties of Black Carbon (BC) radiative forcing are becoming an obstacle to the evaluation of their impacts and mitigation measures. One of the crucial reasons for this uncertainty could be the poorly constrained BC vertical profile. The BC has a lifetime of a few days to weeks and there is a clear pointer that it can be vertically transported through convection besides the horizontal advection. The present study aims for the intercomparison between the BC mass concentrations obtained through the aircraft-based observations and that derived from the selected Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data over the three different locations of India, which is one of the largest emitters of BC aerosols. The aircraft-based BC observations were conducted from 0.5 to 7 km altitudes using Aethalometer during CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement Experiment) Phase I campaigns from June to September 2009. The output of the present study suggests the CAMS reanalysis data significantly underestimated BC mass throughout the vertical profile with an average mass normalized mean bias of greater than -70% at all three locations. Furthermore, the vertical radiative forcing and heating rates of BC were also calculated for both observation and reanalysis data. The output depicts the net forcing due to CAMS simulated BC in all the layers were 1-12 folds lower over all the study regions compared with observed BC aerosols. Likewise, the estimated mean biases in heating rate were in the range of -0.001 to -0.190 K day(-1) for all the vertical layers over the study locations. The possible reasons for these disparities could be poorly constrained emissions, especially aircraft emissions and/or their transformation schemes in aerosol modules. The present study emphasized that the validation of the vertical profile is also an essential factor for better constraints of the BC aerosols in climate models.