# Analysis of Liquefaction in Tailings Deposits by Fem Modeling of Underained Cyclic Triaxial
## 8 Conclusions  
In this study, an undrained consolidated cyclic triaxial test (CTX) was modeled and calibrated using the UBC3D-PLM and HSS constitutive models in the Plaxis2D(r) software. The results indicate that by applying the UBC3D-PLM model for the cycling phase and the HSS model for the isotropic consolidation phase, it is possible to accurately represent the initiation of liquefaction under cyclic loading conditions in silty and sandy soils typical of mining tailings in northern Chile.  
The UBC3D-PLM model effectively represented the excess pore pressure in the calibrated tests, validating its ability to simulate the cyclic response of saturated sandy soils. Furthermore, the model also provided a better simulation for silty soils, despite being originally designed for sandy soils. It was observed that the model's accuracy decreases when a single set of parameters is used across different levels of deviatoric stress, highlighting the importance of specific calibrations for each loading condition. Additionally, the simulation underestimated the rate of stiffness degradation and the strains in sandy soils, suggesting that further adjustments are needed to accurately capture these phenomena under varying stress states.  
The study identified that the primary parameters influencing the constitutive model's response are \(f_{dens}\), \(K_{G}^{p}\) and \(f_{post}\), each affecting the model differently: (i) \(f_{dens}\) and \(K_{G}^{p}\) adjust the number of cycles required for liquefaction and (ii) the parameter \(f_{post}\) fine-tunes the post-liquefaction response, preventing excessively high pore pressures. Although other parameters can also be varied, they generally remain close to values reported in the literature.  
The UBC3D-PLM model exhibits limitations in accurately representing stiffness degradation under dynamic conditions. In particular, it tends to underestimate the rate of stiffness degradation, especially in sandy soils, potentially leading to inaccurate representations of accumulated deformations and soil responses under prolonged cyclic loading. These shortcomings may compromise the precision of results in scenarios where cyclic loads vary significantly in amplitude and frequency.  
The findings of this study provide a strong foundation for future applications involving calibrations under similar loading conditions, such as modeling structures like slopes, tailings dam walls, and wind farm foundations. Additionally, the calibration and modeling methodology can be replicated with a larger database of cyclic triaxial tests under various loads, relative densities, and confining stresses, such as the data provided by [PERSON] [17], which are freely available online ([[https://www.torsten-wichtmann.de/KFSDB.htm](https://www.torsten-wichtmann.de/KFSDB.htm)]([https://www.torsten-wichtmann.de/KFSDB.htm](https://www.torsten-wichtmann.de/KFSDB.htm)), accessed on 22 June 2024).  
Conceptualization, A.R., J.B. and R.G.-S.; methodology, A.R., J.B. and R.G.-S.; formal analysis, A.R., J.B. and R.G.-S.; investigation, A.R., J.B., R.G.-S. and J.E.O.-V.; resources, R.G.-S.; data curation, R.G.-S.; writing--original draft preparation, A.R., J.B. and R.G.-S.; writing--review and editing R.G.-S.; supervision, [PERSON], [PERSON] and [PERSON]; project administration, [PERSON]-S. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Vice-Rectorate for Research, Creation and Innovation (VINCI-DI) at Pontificia Universidad Catolica de Valparaiso, Project 039.489/2024.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflicts of interest.