Commercial software packages for FEM analysis have been used to numerically simulate the behaviour of the complex systems of bentonite-bonded sand mould under pressure and subjected to stress distributions and to predict their performance. The Drucker-Prager model and the Mohr-Coulomb model are two well-known mathematical models used to describe the plastic non-linear behaviour of the soil. Conducting direct shear tests on varying densities of sand can provide the individual parameters necessary for the simulation of the moulding process. A new approach is based on making relationships between micro-mechanical parameters and changes in sand density during the compaction process. COMSOL Multiphysics is a popular software tool used to implement FEM simulations. The steps involved drawing geometry, inserting material properties, mesh generation and time-dependent density, and solving the model. The boundary conditions depend on the particular problem being analysed, which defines the external forces and constraints acting on the structure. The use of a coarse mesh and stationary study may be a computationally efficient approach for the evaluation of the compaction process of green sand. The study found that the maximum displacement value is 6.1*10-3 mm, the maximum volumetric strain value is 8.88*10-5, and the von Mises stress is 4.14*103 N/m2. On a utilise des progiciels commerciaux disponibles pour l'analyse FEM pour simuler numeriquement le comportement des systemes complexes de moules en sable lie a la bentonite sous pression et soumis a des distributions de contraintes, et pour predire leurs performances. Le modele Drucker-Prager et le modele Mohr-Coulomb sont deux modeles mathematiques bien connus utilises pour decrire le comportement plastique non lineaire du sol. Mener des essais de cisaillement directs sur des densites variables de sable peut fournir les parametres individuels necessaires a la simulation du procede de moulage. Une nouvelle approche est basee sur l'etablissement de relations entre les parametres micromecaniques et les changements de densite du sable au cours du procede de compactage. COMSOL Multiphysics est un outil logiciel populaire utilise pour mettre en oe uvre des simulations FEM. Les etapes impliquaient le dessin de la geometrie, l'insertion des proprietes des materiaux, la generation du maillage et de la densite en fonction du temps, ainsi que la resolution du modele. Les conditions aux limites dependent du probleme particulier analyse, qui definit les forces et les contraintes externes agissant sur la structure. L'utilisation d'un maillage grossier et d'une etude stationnaire peut constituer une approche informatique efficace pour evaluer le procede de compactage du sable vert. L'etude a trouve que la valeur de deplacement maximale etait de 6.1*10-3 mm, la valeur de deformation volumetrique maximale etait de 8.88*10-5 et la valeur de contrainte de von Mises etait de 4.14*103 N/m2.

The tensile strength is an important parameter in engineering. Many engineering-related problems in buildings as well as the damage caused to them during natural disasters occur owing to a lack of tensile strength. The unconfined penetration (UP) test is an indirect method to measure the tensile strength of soil. Analyses of the mechanism of the UP test and simulations based on the discrete-element method have shown that the UP test is a complex process involving tensile and shear strengths. In this study, the authors use the modified Mohr-Coulomb model to establish a joint criterion for the failure of the tensile strength and the shear strength of loess, and derive expressions for the correlations between the relevant mechanical parameters. A combination of the results of the aforementioned model and laboratory tests showed the following: (1) the process of failure of loess samples during the UP test consisted of four stages: (I) the shaping of the wedge-shaped split body, (II) tension-induced fracture, (III) the yield stage, and (IV) damage to the sample; (2) the tensile strength of the loess decreased exponentially with its saturation; (3) the ratio of the unconfined compressive and cohesive strengths to the tensile strength of the remolded loess was 1.37 times that of the undisturbed loess, while the ratio of the unconfined compressive strength of remolded loess to its cohesion was similar to that of undisturbed loess; (4) the wedge-splitting angle ranged from 13 degrees to 23 degrees, and had a negative correlation with the internal angle of friction, a positive correlation with the water content, and decreased exponentially with the tensile strength.

Vegetation restoration processes significantly affect near-surface characteristics, thus affecting soil detachment. Existing research has primarily focused on analysing soil detachment via root morphological parameters and soil physical and chemical properties. However, few studies have focused on analysing the variation in soil detachment with restoration age from a mechanical parameter perspective. Natural, undisturbed soil samples were collected from five grasslands restored for 1-22 years and from one bare plot (0 years of restoration, employed as the control). The collected samples were subjected to flow scouring in hydraulic flume experiments under six stream powers. The relationship between the soil detachment rate (SDR) and the mechanical parameters of the root-soil composites, namely root cohesion and soil shear strength (tau 200), were quantified to reveal the mechanical mechanism underlying soil detachment during vegetation restoration. The results indicated that the SDR decreased, whereas root cohesion increased with increasing vegetation restoration age. The dominant factors influencing the SDR changed from hydrodynamics at the early restoration stage to the mechanical properties of the root-soil composites at the late stage. An SDR model with a high prediction accuracy (Nash-Sutcliffe efficiency = 0.96 and R2 = 0.96) was developed based on mechanical parameters, and the fitting effect was greater than that of the SDR prediction model developed based on root morphological parameters and soil physical and chemical properties. This study aimed to analyse the SDR variation mechanism from the perspective of mechanics and could provide reference for the study of the erosion reduction effect of roots.

Understanding the mechanical changes of marine soft soil under temperature is crucial for the construction and long-term operation of submarine pipelines. A series of basic physical and mechanical properties tests was carried out on the marine soft soil in Shanwei, Guangdong province. X-ray diffraction, X-ray fluorescence spectrometry, and scanning electron microscopy were employed to achieve the marine soft soil's mineral composition, element composition and microstructure. The consolidated undrained laboratory tests under isotropic consolidation and biaxial consolidation conditions were carried out using a temperature-controlled triaxial apparatus. The test results revealed significant findings. Firstly, when the axial strain is small, the undrained shear characteristics of saturated marine soft soil are influenced by the ambient temperature and the consolidation stress ratio. Specifically, a higher ambient temperature or a smaller consolidation stress ratio results in a greater secant modulus. The secant modulus exhibits an inverse relationship with the consolidation stress ratio and demonstrates a power function relationship with the ambient temperature. As the axial strain increases, the peak strength of the soil is affected by both ambient temperature and consolidation stress ratio, while the peak pore pressure is less affected by ambient temperature. Furthermore, the initial dry density of the sample was found to impact the undrained shear characteristics of the isotropic consolidated soil (K-c=1.00). A greater initial dry density resulted in a smaller peak pore pressure, a greater peak strength, and a more significant decrease in peak strength with rising temperature. Additionally, the consolidation stress ratio was observed to affect the peak strength and effective stress path of saturated marine soft soil under different ambient temperatures. Specifically, when K-c=1.00 or 0.67, an increase in the ambient temperature softened the saturated marine soft soil; whereas when K-c=0.50 or 0.40, the rise in ambient temperature hardened the soil.

The uncertain mechanical parameters of clay layer under torrential rain are the key to the dynamic evolution process and stability assessment of landslide geological hazards. Due to the complex environment, engineering geology and physical chemistry process, the mechanical parameters of clay layer show significant spatial variability and correlation. In addition, due to technical and economic conditions constraints, the actual investigation and test data of soft cohesive soil are very limited, which seriously restricts the stability evaluation of clay slope and the prevention of instability disaster. To characterize anisotropic spatial variations of uncertain mechanical parameters for clay layer using incomplete probability data, the elastic modulus, Poisson ratio and shear strength under saturated conditions were measured, and statistical data and variation properties of uncertain mechanical parameters were analyzed. A modeling approach was proposed for characterizing incomplete probability data of clay layer. The accuracy of the proposed approach is verified by comparison of the statistical characteristic for measured data and simulated data. A novel linear fitting method was proposed for assessing scale of fluctuation and autocorrelation distances. The variability and correlation of uncertain mechanical properties for soft cohesive soil layer are discussed. The results show that the mechanical properties of the clay layer are uncertain in spatial position. Both the original observation data and the simulated data of three mechanical parameters have symmetrical correlation structure. The clay layer display the horizontal layered structure on the soil profile, and the vertical autocorrelation distances are shorter than the horizontal distances. This paper clearly illustrates the anisotropic spatial variations of uncertain mechanical parameters for clay layer using incomplete probability data and it can provide scientific data for the uncertainty analysis and risk assessment of clay slope under torrential rain conditions.

The purpose of this experimental research based on physical and mechanical tests is to analyze three brands of Portland GU cement widely marketed in the construction industry of Honduran in civil works in order to have scientific evidence documenting their behavior in hydraulic concrete. With the results obtained, the compressive strength at 7 and 28 days [f'c] according to ASTM C39 and the slump according to ASTM C143 were compared through current standards. The results obtained are as followed: Wan Peng with a compressive strength of 5907.51 psi and its slump of 6.25 in, Bijao with 4282.01 psi and 2.09 in and finally Argos with 4024.82 psi and 4.08 in respectively, Wan Peng cement is in the national market since 2018 and shows results of mechanical parameters in hydraulic concrete superior to those obtained with other brands that are older in the country. It is recommended to perform a physicochemical analysis of Wan Peng cement as well as an iterative analysis that provides a different water-cement ratio, also different applications could be performed with this cement for example about soil stabilization and manufacture of blocks in the latter to see the thermal behavior when used in the construction of houses and buildings.