This paper investigates the role of masonry elastoplastic constitutive models on tunnelling-induced damage in buildings. A two-stage analysis method (TSAM) is adopted, incorporating input greenfield displacements, 3D masonry walls, and an elastic model for the soil. The paper focuses on four masonry constitutive models that can be readily adopted for routine analysis in industry. Comparison of in-plane yield surfaces with experimental data indicates that, among the considered masonry models, the Concrete Damaged Plasticity model under biaxial calibration gives the best overall performance. The TSAM is then used to study selected tunnel-masonry wall scenarios, confirming a significant effect of the constitutive model and its parameters on masonry wall response to tunnelling, particularly after volume losses where moderate damage is triggered. Also, as masonry stress paths are shown to concentrate in the tensile-compressive areas, with damage prediction being sensitive to the yield surface within this quadrant, numerical damage predictions must rely on the accurate calibration of the constitutive model in the tensile-compressive quadrants. This appraisal indicates that, in the context of routine structure modelling for tunnelling assessments, the selection of elastoplastic masonry models and their biaxial calibration have a non-negligible impact on the damage category estimate.

Numerical simulation of the stress-strain behavior of materials under various loading conditions requires an appropriate constitutive model, with the yield surface being one of its key components. Extensive studies have been conducted to identify the yield surface of soil materials (sand and clay) through laboratory methods. However, the identification of the yield surface of waste materials has received less attention to date. Waste materials are artificial soil-like substances produced during the crushing and concentration processes in mineral processing plants. In this paper, a laboratory program was carried out using an advanced triaxial stress-path and stress-control apparatus on reconstructed saturated samples from the Sungun mine, located in the northwest of Iran. These samples were reconstituted using the wet tamping method. Through analysis and interpretation of the results, the yield surfaces of these lightly over-consolidated materials, with both isotropic and anisotropic initial consolidation conditions, were determined. The dependency or non-dependency of the obtained yield surfaces was evaluated, and the effect of consolidation stress and the angle of the applied stress path on the variation trends of the secant shear modulus and secant bulk modulus-indicating structural anisotropy of the waste materials-were assessed. Finally, the structural anisotropy of the samples was examined using SEM images and statistical processing of particle orientation and a mathematical model for the obtained yield surfaces was proposed.

Cyclic loading may induce changes in the geomechanical behaviour of materials that should be characterised. This work studies the impact of the number of loading cycles on the mechanical behaviour of a fibre-reinforced stabilised soil focusing on its behaviour before failure (yield surface). To this end, an experimental testing program based on triaxial tests was performed on samples not subjected to a cycling loading stage, as well as on samples previously subjected to a cycling loading stage varying the number of loading cycles from 1,000 to 100,000. The results were studied in terms of the accumulated permanent axial strain and the yield surface of the composite material. It was observed that increasing the number of loading cycles led to a rise in the accumulated permanent axial strain and in the undrained resilient modulus. The results also showed an expansion of the yield surface during the first 1,000 loading cycles (the yield occurs later due to the partial mobilization of the tensile strength of the fibres during the cyclic stage) but its shape is maintained. The results also showed a progressive reduction in the yield loci with the increase in the number of loading cycles, reflecting the greater degradation of the solid matrix induced by the accumulated permanent axial strains.

When a soil is subjected to cyclic loading, there are changes in the material's geomechanical behaviour that need to be characterized before safely designing any future projects. In terms of cyclic loading, it is important to characterise not only the failure of the soil but also its behaviour before failure, in particular the yield point and the elastic behaviour of the material. This study examines the effects of the number of loading cycles on the behaviour of a chemically stabilised soft soil with a particular focus on the yield surface. To this end, a series of triaxial tests were performed on specimens, previously or not subjected to a different number of loading cycles (1,000-100,000). The results were analysed in terms of the evolution of accumulated permanent axial strain, the yield surface and stress-strain behaviour. It was observed that an increase in the number of loading cycles promoted: an increase in the permanent axial strain, an increase in the undrained resilient modulus, a shrinkage of the yield surface but its shape is maintained, and there is a small increase in the peak strength of the stabilised soil explained by the strain hardening effect induced by the cyclic loading.

When unsaturated soils are affected by thermal radiation such as sunlight, geothermal heat, nuclear waste, and biochemical reactions, the soil temperature will increase and accelerate soil moisture migration, resulting in soil deformation. Therefore, in this paper, by extending the SFG model of the unified yield surface to consider the effect of temperature change on the unified yield surface, a yield surface constitutive model which can simultaneously reflect temperature-suction-stress is proposed. In order to verify the applicability of the model, the triaxial test of Jiangxi laterite at different temperatures is carried out to determine the calculation parameters of the model, and the fitting results of the model are compared with the experimental results, and the model is fitted and analyzed by referring to the test data of remolded clay used by Uchaipichat. The results show that the model can well reflect the stress-strain characteristics of soil during compression rebound, dehumidification and shear at different temperatures, which provides a theoretical support for predicting and solving the influence of temperature change on the stress deformation and shear strength of unsaturated soil in the corresponding engineering environment in the future, thus further enriching the constitutive theory of unsaturated soil under the influence of temperature.