This study quantifies the seismic fragility assessment of shallow-founded buildings in liquefiable and treated soils, enhanced by drainage and densification, considering both short-and long-term behaviors. A conceptual framework is proposed for developing seismic fragility curves based on engineering demand parameters (EDPs) of buildings subjected to various earthquake magnitudes. The framework for establishing seismic fragility curves involves three essential steps. First, nonlinear dynamic analyses of soil-building systems are performed to assess both the short-term response, which occurs immediately following an earthquake, and the longterm response, when excess pore water pressure completely dissipates, and generate a dataset of building settlements. The seismic responses are compared in terms of excess pore water pressure buildup, immediate and residual ground deformation, and building settlement to explore the dynamic mechanisms of soil-building systems and evaluate the performance of enhanced drainage and densification over short-and long-term periods. Second, 38 commonly used and newly proposed intensity measures (IMs) of ground motions (GMs) are comprehensively evaluated using five statistical measures, such as correlation, efficiency, practicality, proficiency, and sufficiency, to identify optimal IMs of GMs. Third, fragility curves are developed to quantify probability of exceeding various capacity limit states, based on structural damage observed in Taiwan, for both liquefaction-induced immediate and residual settlements of buildings under different levels of IMs. Overall, this study proposes a rapid and straightforward probabilistic assessment approach for buildings in liquefiable soils, along with remedial countermeasures to enhance seismic resilience.

The use of permeable piles as an effective drainage method in liquefiable sites has become widely accepted. In this study, the seismic response of both the liquefiable soil and the pile was simulated using FLAC3D software to validate the anti-liquefaction performance of the permeable pile. A group of permeable piles designed according to the China foundation code were numerically modeled with various opening ratios (i.e. area of openings/total surficial area). The numerical results showed that the permeable pile is able to enhance liquefaction resistance by dissipating excess pore water through the drainage holes. The bending moments and axial force of the permeable pile decrease but the ultimate bearing capacity increases in the process of drainage. It is found that the excess pore water pressure ratio (EPWPR) of soil around permeable pile under seismic loading reduces rapidly with increasing opening ratio, but the excess pore water pressure tends to keep nearly a stable level once the opening ratio is beyond a critical value of 0.5%. As a result, the critical value of the opening ratio may be considered as the optimum parameter to design the permeable pile against liquefaction.

The utilization of cone penetration test (CPT & CPTu) results to assess the bearing capacity of deep foundations stands as a crucial application in geotechnical engineering. This study focuses on leveraging the outputs of the CPT test, considering the distinctive features of piles and the abundance of reliable information, coupled with the rapidity of the test. The CPT test outcomes can be employed both directly and indirectly to ascertain the capacity of the toe and shaft resistance of piles. In seismic conditions, applying earthquake acceleration to sensitive and liquefiable soils induces an increase in pore water pressure Delta u, leading to a subsequent reduction in soil strength. Thus, investigating changes in excessive pore water pressure serves as a key dynamic load indicator in seismic scenarios. This research initially determines the bearing capacity of deep foundations through common methods using CPT data. Subsequently, key parameters influencing the development and dissipation of Delta u, such as soil sensitivity (St), undrained shear strength (Su), and dimensionless parameters of pore water pressure 1-Bq\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {1 - B_{q} } \right)$$\end{document} and 1-u2qt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {1 - \frac{{u_{2} }}{{q_{t} }}} \right)$$\end{document}, are meticulously evaluated. This study proceeds to investigate the impact of these parameters on the bearing capacity of deep foundations, drawing insights from a comprehensive database encompassing CPT & CPTu data from 18 diverse sites worldwide. Comparative analysis between the proposed method and conventional approaches reveals a significant reduction in the aforementioned parameters' influence on the bearing capacity of deep foundations. Consequently, this finding underscores the necessity of incorporating such considerations in geotechnical bearing capacity calculations for projects situated on soils prone to liquefaction.

Large diameter shield tunnels traversing liquefiable soil-rock strata are highly susceptible to seismic hazards, as earthquake-induced soil liquefaction significantly reduces soil strength and stiffness. Therefore, it is crucial to accurately assess the seismic performance of these tunnels. This study first establishes a numerical model for tunnel seismic response analysis, considering soil liquefaction, segment nonlinearity, and joint deformation. The validity of the model is affirmed through experimental, theoretical, and additional numerical simulations. The probabilistic seismic demand models are established employing the seismic database consisting of 120 ground motion records. Subsequently, a quantitative selection method for the optimal Intensity Measure (IM) based on fuzzy comprehensive evaluation is proposed, identifying Velocity Spectrum Intensity (VSI) as the most suitable among 29 commonly used IMs, and the IMs related to duration exhibit poor performance. The study then categorizes tunnel damage into three states: minor, moderate, and extensive, using joint opening as the damage measure. Finally, seismic fragility analysis is employed to assess seismic performance of tunnel, and fragility curves derived using VSI and Peak Ground Acceleration (PGA) is compared. The results indicate that PGA, a commonly used IM, significantly underestimates the probability of damage to the tunnel, with a maximum underestimation of 22.4%.

Historical data has shown that soil-structure systems exhibit increased severity when subjected to earthquake sequences, attributed to the accumulated instability of soil deposits and the cumulative damage of structures. This study analyzes seismic responses of multi-story buildings and mechanical behavior of liquefiable soil deposits under repeated shake-consolidation process. This is achieved through a series of numerical simulations using a finite element-finite difference (FE-FD) code, namely DBLEAVE-X. Sequential earthquakes are obtained from the NGA-West2 PEER ground motion database and recalibrated relied on various aspect ratios, including peak ground acceleration ratios (rPGA) and consolidation time (Tgap). The numerical results reveal that shearinduced and residual settlements of buildings during sequential earthquakes might be notably larger than that during single earthquakes. The repeated shake-consolidation process has a significant impact on development and dissipation of excess pore water pressure (E.P.W.P), notably influencing the deformation response of both buildings and ground deposits. The findings also provide valuable insights into effects of both complete and partial consolidation processes on seismic mechanisms of entire liquefiable soil-structure systems. Numerical observations suggest that multi-story buildings under sequential earthquakes might be more vulnerable, underscoring the necessity of integrating sequential earthquakes into earthquake-resistant building design.

In this study, a series of shake table tests were conducted on saturated sand soil foundations to investigate the seismic response of pile-supported railway embankments under equal and unequal thickness heterogeneous liquefiable soil conditions. The model's failure process, the variations of excess pore water pressure, the bending moments of the pile, and the acceleration response under different seismic intensities were analyzed in detail. Test results showed that the pore pressure increased with the increase of seismic intensity, and the liquefaction phenomenon occurred in the loose sand layer under 0.2 g dynamic excitation. The growth rate and peak value of excess pore water pressure in unequal thickness liquefiable soil terrain were greater than that in equal thickness soil conditions. The maximum bending moment of the pile body exhibits an inverted S-shaped distribution. In unequal thickness soil conditions, the edge piles experience higher bending moments compared to those in terrains with the same thickness. Additionally, the position of the maximum negative bending moment distribution for the central pile underwent a noticeable downward shift. During the loading process, the amplification effect of acceleration was greater in the loose sand layer than in the gravel soil layer, and more significant at the center of the foundation or the subgrade in unequal thickness liquefiable soil conditions. Therefore, the influence of terrain factors on the rise of pore pressure and the distribution of pile bending moments was nonnegligible in the seismic design of pile-supported embankment.

Liquefaction poses a potential threat to the safety, serviceability and stability of shield tunnels during seismic events. This study investigates the seismic response of shield tunnels in liquefiable soils employing a fully coupled dynamic effective stress analysis model. The model accounts for the nonlinear mechanical behavior of the shield tunnel structure and incorporates the advanced bounding surface elastoplastic PM4Sand and PM4Silt models integrated with Biot u - p formulation to simulate the constitutive behavior of liquefiable and nonliquefiable soil layers. The seismic performance of shield tunnel -liquefiable soil system is evaluated considering ground motions with different characteristics in the transverse direction. The numerical results reveal the significant effects of ground motion frequency content and seismic intensity on the liquefaction triggering, the tunnel deformation and the internal forces of segmental joints. The soil -structure dynamic interaction and the soil shear dilatancy characteristics greatly influence the generation of the earthquake -induced excess pore water pressure and post -liquefaction shear strains. It is observed that the soil contact pressures on the left and right springlines of the tunnel experience larger increase compared to the contact pressure on the tunnel crown and invert. This observation suggests that the soil could cause racking deformation on both sides of the tunnel structure towards the center. Besides, the deformations and mechanical behaviors of the segmental joints around the tunnel left and right feet and the right springline are notably higher than at other joints in the saturated deposits. Furthermore, it is found that ground motion characterized by low -frequency contents, amplifies the seismic response of the soil and the tunnel when compared to the ground motions with high or moderatefrequency contents.

Subway systems are a crucial component of urban public transportation, especially in terms of safety during seismic events. Soil liquefaction triggered by earthquakes is one of the key factors that can lead to underground structural damage. This study investigates the impact of deep soil liquefaction on the response of subway station structures during seismic activity, aiming to provide evidence and suggestions for earthquake-resistant measures in underground constructions. The advanced finite element software PLAXIS was utilized for dynamic numerical simulations. Non-linear dynamic analysis methods were employed to construct models of subway stations and the surrounding soil layers, including soil-structure interactions. The UBC3D-PLM liquefaction constitutive model was applied to describe the liquefaction behavior of soil layers, while the HS constitutive model was used to depict the dynamic characteristics of non-liquefied soil layers. The study examined the influence of deep soil liquefaction on the dynamic response of subway station structures under different seismic waves. The findings indicate that deep soil liquefaction significantly increases the vertical displacement and acceleration responses of subway stations compared to non-liquefied conditions. The liquefaction behavior of deep soil layers leads to increased horizontal effective stress on both sides of the structure, thereby increasing the horizontal deformation of the structure and posing a potential threat to the safety and functionality of subway stations. This research employed detailed numerical simulation methods, incorporating the non-linear characteristics of deep soil layer liquefaction, providing an analytical framework based on regulatory standards for evaluating the impact of deep soil liquefaction on the seismic responses of subway stations. Compared to traditional studies, this paper significantly enhances simulation precision and practical applicability. Results from this research indicate that deep soil layer liquefaction poses a non-negligible risk to the structural safety of subway stations during earthquakes. Therefore, the issue of deep soil liquefaction should receive increased attention in engineering design and construction, with effective prevention and mitigation measures being implemented.

The typical undrained behaviour observed in brittle non-plastic soil is ruled by the combination of density and stress levels. Some specific silty and sandy mining waste with particles morphologies that generate high small-strain stiffness to strength ratios when increasing deviatoric stress (q) in stress paths that tend to decrease mean effective stress (p ') may drop down the deviatoric stress before reaching the frictional critical sate. The ratio between the peak (or yield) value (S-u=q/2) and the corresponding p ' is usually associated with a locus in q-p ' that is commonly associated to a straight Instability Line (IL) with a unique ratio (eta(IL)) and for an initial state parameter. However, this is not the case if an induced anisotropy is installed differently while the at rest stress ratio (hereby defined as initial, K-0) is achieved by continuous rate the principal stresses consolidated in lab prior to loading with distinct values. This fabric effect is decisive for design and in stability assessment of earth structures, like dams or piles of mine tailings where non-plastic fines are dominant, even if the prevailing stress-path is in compression. In a thorough and quite complete program varying these conditions on iron ore tailings from Minas Gerais state in Brazil, reconstituted in lab with differentiated state parameters, and its relation to the induced anisotropy effect.