Filtered tailing is a relatively-environmentally friendly technique due to the recovery of water during the process of dehydration. This technique was recently developed and therefore there are few studies available compared to research on conventional tailings. This work focuses on the behaviour of a filtered copper tailing under an unsaturated condition, studying the effect of self-compaction by self-weight which is triggered by the deposition process through 1D consolidation tests. In addition, the impact of confinement on the stiffness and shear strength was studied by means of unsaturated drained triaxial tests. The initial matric suction was determined based on soil-water characteristic curves for two initially loose dry densities and the water content at which the material leaves the dehydration process. The unsaturated consolidation tests showed that for vertical stresses above 100 kPa and with ratios between the applied matric suction and air entry value lower than twelve, the material approaches saturated condition, reaching up to 95% degree of saturation. On the other hand, for the unsaturated drained triaxial tests, the effect of the matric suction generates increases in the shear strength and the stiffness of the material up to 200% and 600%, respectively. However, the increase tends to disappear as confinement increases.

This study focuses on the numerical modeling of one-dimensional consolidation of filtered copper tailings under saturated and unsaturated conditions using Plaxis2D^®. The modeling is based on 1D consolidation curves under saturated conditions and controlled matric suction. The Soft Soil and Hardening Soil constitutive models were employed, incorporating the soil–water characteristic curve (SWCC) to capture hydro-mechanical behavior and volumetric strain. The modeling strategy replicates the loading and drainage conditions of the experimental tests, using a single set of soil parameters to represent the transition from unsaturated to saturated conditions. Axisymmetric simulations were conducted to replicate the geometry of the experimental specimen, considering initial saturation degrees of 60%, 80%, and 99%, followed by the application of vertical stresses ranging from 10 to 3200 kPa. The results demonstrate that the proposed modeling approach accurately represents the compressibility curve for both constitutive models across different saturation levels. This provides flexibility for conducting numerical analyses tailored to specific soil conditions and geotechnical design requirements. Furthermore, modeling allowed for the evaluation of excess pore pressures and their dissipation time under both saturated and unsaturated conditions.

The representation and assessment of static liquefaction in mine tailings is a significant challenge due to the severe environmental and social damage it can cause. This phenomenon, known for its catastrophic nature, is triggered when the undrained shear strength is exceeded by a static loading stress. In this study, the constitutive models HSS and NS were evaluated to calibrate the experimental curves from an isotropically consolidated undrained (CIU) triaxial test on a low-plasticity silt derived from mine tailings. An axisymmetric model was developed in Plaxis 2D for calibration, followed by a sensitivity analysis of the parameters of both constitutive models, using the RMSE to validate their accuracy. The results indicate that the proposed methodology adequately simulates the experimental curves, achieving an RMSE of 8%. After calibration, a numerical model was implemented to evaluate the propagation of the PFS of a mine tailings storage facility using both models, in terms of excess pore pressures, shear strains, and p’-q diagrams at three control points. The results show that both models are capable of representing the PFS; however, the HSS model reproduces the experimental curves more accurately, establishing itself as an ideal tool for simulating undrained behavior and, consequently, the phenomenon of static liquefaction in mine tailings.

The seismic performance assessment of timber structures and topology optimization have been widely researched in recent years. Furthermore, the use of wood as a construction material has increased due to new sustainability challenges. This research assesses the seismic performance of a topologically optimized timber building located in Concepcion, Chile. The structure is a five-story glulam braced frame, designed following current Chilean standards. The structural configuration was obtained through a topology optimization process using a variation of a soft-kill BESO algorithm implemented in MATLAB R2015a, obtaining topologies with low structural redundancy. For the analysis, a full 3D nonlinear model was prepared using OpenSees (Version 3.7.1), and the nonlinear behavior of the structure was only considered at joints using the backbone curves introduced in ASCE 41-13. Six different study cases were analyzed, varying joint strengths and ductility. The fragility curves were determined from a static pushover analysis (SPO) using SPO2FRAG (V1.1), considering the performance levels established in ASCE 41-13. The seismic hazard of the building’s site is estimated through a probabilistic seismic hazard analysis (PSHA), and the seismic performance of each case is determined by computing the probabilities of exceedance of the considered limit states. Analysis results show that wood braced-frame structures with low structural redundancy (and fewer main joints to dissipate energy), such as those obtained from topology optimization algorithms, exhibit a markedly brittle behavior with almost no displacement ductility. This undesirable behavior does not improve by providing more deformation capacity to this structure’s reduced number of main joints. Currently, the Chilean standard for seismic design requires a unique response modification factor R for wood structures. This research suggests that this requirement should be revisited, specifying different R values depending on the wood structure’s redundancy, considering that its displacement ductility comes almost exclusively from the nonlinear deformation capacity of joints.

This study investigates slope stability under rainfall infiltration using numerical modeling in Plaxis 2D, comparing poorly graded sand (6.5% fines) and well-graded sand (11.9% fines) under high-intensity rainfall of 30 mm/h for durations of 8, 12, 18, and 24 h. The results indicate that, as rainfall duration increases, soil saturation rises, leading to reduced suction, lower shear strength, and decreased safety factors (S.F.s). Poorly graded sand shows minimal sensitivity to infiltration, with the S.F. dropping by only 4.3% after 24 h, maintaining values close to the initial 1.126. Conversely, well-graded sand demonstrates significant sensitivity, with its S.F. decreasing by 25.4% after 8 h and 73.7% after 24 h, due to higher water retention capacity and suction. This highlights the significant contrast in stability behavior between the two soil types. The findings emphasize the critical role of soil hydro-mechanical properties in assessing slope stability, especially in regions with intense rainfall. This study establishes a methodology for correlating safety factor variations with rainfall duration and soil type, offering valuable insights for modeling and mitigating landslide risks in rainy climates, considering the hydraulic and mechanical parameters of the soil.