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.

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.

Natural disasters called landslides have the potential to seriously harm people's safety, the environment, and structures, in addition to causing considerable damage to infrastructure. It is therefore important to be able to model and predict these phenomena. This paper focus on modeling non-linear processes using a finite element model behavior and assess the stability of a slope by calculating the safety coefficient. The characterization work was carried out on a landslide at the site located in Tizi-Ouzou (Algeria). It is characterized by steepness greater than 20%. Verification of the stability of this area, while taking into account the morphology and local geological context of the site, was carried out by finite element modeling using the Mohr-Coulomb criterion and adopting the Cam-Clay model in a Castem step-by-step non-linear calculation code, making it possible to extract the stress field, displacements and deformations and also to find the sliding surface corresponding to a minimum FOS safety coefficient. The results obtained highlight the areas of the slope undergoing plastic deformation, indicative of a high state of stress. The results make it possible to identify the weak points that show that the studied profile is exposed to a risk of landslide, in particular a deep landslide affecting soil layers with a safety factor FOS <1. Preventive actions are recommended to secure the site where supporting measures could be considered.

This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling. Laboratory tests were conducted to determine the soil parameters used in the modified Cam-Clay (MCC) model. Intelligent field monitoring means were adopted and a three-dimensional model was established. Spatial and temporal effects induced by the excavation are investigated for the deep -large foundation pit in soft soil. Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented. The behaviors of diaphragm walls, columns, the maximum wall deflection rate, ground surface settlement, and utility pipelines were focused on and investigated during the whole excavation process. Besides, the axial forces of the internal supports are analyzed. Based on the measured and simulated data, the following main conclusions were obtained: the numerical simulation results are in good agreement with the measured values, which proves the accuracy of the model parameters; the wall and the ground surface showed the maximum displacement increment at stage 9, which was a coupled product of the creep effect of the soft soil in Nanjing, China and the depth effect of the excavation; as the excavation progressed, the ground settlement changed from a rising to a spoon -shaped trend, 6 vm was measured between 6 vm = 0.0686% H and 6 vm = 0.1488% H ; the rebound deformation curve of the pit bottom was corrugated, and the depth of disturbance of the pit bottom after the completion of soil unloading was 2-3 times the excavation depth; the closer the pipeline is to the corner of the pit, the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur; the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.

Computational modelling has been widely used in the geotechnical field to represent soil behaviour in real problems. Most commercial programmes use the Finite Element Method (FEM) to compute stresses and deformations distributions in soils, as observed in Plaxis software. In this method, choosing an appropriate constitutive model is fundamental to obtaining accurate results. However, most models built in commercial software do not consider effects such as overconsolidation and structure, observed for natural soils with structure. The Structured Sub-Loading Cam Clay (SSLCC) model is recommended to represent this behaviour. This article aims to describe a practical methodology to code the SSLCC model to represent the behaviour of structured soils. The model was implemented in Plaxis by the User-Defined Soil Model feature and validated with experimental data of consolidation and drained and undrained triaxial tests performed for different soils. The model implemented presents good performance and can be used in the FEM interface. The methodology described can also be used to introduce any constitutive model in Plaxis.