This paper investigates the effectiveness of a sheet pile wall to reduce railway induced vibration transmission by means of field measurements and numerical simulations. At Furet, Sweden, a sheet ...pile wall has been installed in the soil near the track to reduce train induced vibrations in houses close to the track. The depth of the sheet piles is 12m with every fourth pile extended to 18m. The efficacy of the wall is determined from in situ measurements of free field vibrations during train passages before and after installation of the sheet pile wall. The field test shows that the sheet pile wall reduces vibrations from 4Hz upwards. Up till 16–20Hz, the performance generally increases with frequency and typically decreases with increasing distance behind the wall. The performance is further studied by means of two-and-a-half-dimensional coupled finite element–boundary element models. The sheet pile wall is modelled as an orthotropic plate using finite elements, while the soil is modelled as a layered halfspace using boundary elements. The sheet pile wall acts as a stiff wave barrier and the efficacy is determined by the depth and the stiffness contrast with soil. The reduction of vibration levels is entirely due to the relatively high axial stiffness and plate bending stiffness with respect to the horizontal axis of the sheet pile wall; the plate bending stiffness with respect to the vertical axis is too low to affect the transmission of vibrations. Therefore, it is important to take into account the orthotropic behaviour of the sheet pile wall. It is concluded that a sheet pile wall can effectively act as a wave barrier in soft soil conditions provided that the wall is sufficiently deep.
•A 100m long barrier has been built in the soil along a railway track in Sweden.•The barrier consists of 12m deep sheet piles with every fourth pile extended to 18m.•The wall is effective and results in vibration reduction from 4Hz upwards.•A good agreement between experiments and numerical predictions is found at short distances behind the wall.•The orthotropic behaviour of the wall must be accounted for in simulations.
This study examines the dynamic system response of a liquefiable deposit retained by a sheet-pile wall, with emphasis on the roles of pre- and post-liquefaction stages of soil response. A recently ...developed constitutive model, SANISAND-MSf, is utilized to simulate the pre- and post-liquefaction cyclic response of sands. The model is a stress-ratio controlled, critical state compatible, bounding surface plasticity model, which incorporates the concepts of memory surface and semifluidized state. The model’s performance is validated using a combination of cyclic simple shear tests and dynamic centrifuge tests from the LEAP-2020 project. A sensitivity analysis is then conducted by varying the base input motion intensity and duration. The results reveal that the amplitude of equivalent uniform base acceleration in pre-liquefaction correlates well with the timing of liquefaction triggering, and the cumulative absolute velocity of the base acceleration during the post-liquefaction stage correlates well with the post-liquefaction displacements. The study highlights the importance of accurately simulating response in the pre-liquefaction stage for the extent and timing of occurrence of liquefaction, which regulates the remaining intensity and duration of shaking, and in turn, affects the post-liquefaction permanent deformations at the system level.
•SANISAND-MSf accurately simulates pre- and post-liquefaction cyclic response of sand•Model validated with extensive element-level and centrifuge tests from LEAP-2020•Validated model used for sensitivity analysis on base motion’s max acceleration and duration•Pre-liquefaction response controls liquefaction triggering extent/timing, post-liquefaction controls permanent displacements•āpre and CAVpost of base acceleration correlate with liquefaction timing and post-liquefaction displacements, respectively
•A state of art approach to study limiting pressure behind soil gaps in contiguous pile walls.•Advanced 2D finite element limit analysis for contiguous pile walls.•Comprehensive design charts and ...tables are presented.•A closed-form equation of the limiting pressure factor is presented.
New average FELA solutions for the problem of the limiting pressure behind soil gaps and the lateral force acting on a pile per unit length of a contiguous pile wall in anisotropic clay are investigated in this paper. The anisotropic undrained shear (AUS) model is utilized to determine anisotropic soil behaviour. The limiting pressure factor (N) is derived by varying dimensionless parameters such as the anisotropic ratio (re), the adhesion factor (α), and soil gap ratios (S/D) which are presented in the form of sample charts and tables. The failure patterns of the soil gaps are also conducted and explained in light of the impacting factors. Aclosed-form equation of the limiting pressure factor is presented in order to efficiently and precisely establish and evaluate an undrained limiting pressure behind soil gaps and the lateral force operatingon a pile wall in practice.
It is well-known that the soil environment involves inherent spatial variability, and its characteristics may differ in various layers. Accordingly, a more reliable design of water-front geotechnical ...structures requires the consideration of uncertain spatial changes in the soil. In this research, the stability of anchored sheet pile walls is investigated under the influence of uncertainties in soil and structure using a novel fuzzy logic-based approach. The spatial variability is considered by layering the soil according to different profiles representing variations in soil parameters. The genetic algorithm is used to calculate the fuzzy safety factors of overturning, sliding, and flexural failure modes at different uncertainty levels. By computing the probability of failure and the reliability index, a comparison is made between the results of all profiles. Several graphs are provided to assist geotechnical engineers in the more robust and economical design of sheet pile walls. The results indicate that accounting for the uncertainties and variability of the soil parameters is of crucial importance for the stability analysis. Finally, it is found that the developed technique, considering the profiles reflecting a more realistic distribution of the soil parameters and their uncertainties, could result in a greater reliability of the system.
•Fuzzy safety factors are considered to assess sheet pile stability under input uncertainties.•Soil spatial variability is taken into account by layering according to different profile types.•A hybrid approach coupling fuzzy logic and optimization is used for uncertainty analysis.•Reliability of design is evaluated by determining probability of different failure modes.•Target probability-based design charts are provided for anchored cantilever sheet pile wall.
This paper outlines the findings derived from a study conducted within the LEAP-2022 project, focusing on analyzing the seismic response of a sheet-pile retaining structure that supports liquefiable ...soils. The primary objective is to assess the efficacy of two distinct constitutive models–Manzari-Dafalias (MD) and PM4Sand–following their calibration utilizing element tests conducted on Ottawa-F65 sand. By employing these calibrated models, finite element models are generated to emulate centrifuge experiments. The results indicate that both the MD and PM4Sand models adequately capture the behavior of liquefiable soils and consequent wall displacements. Furthermore, the study emphasizes the significance of accurately calibrating for cyclic stress demands at the wall’s toe and the passive zone to precisely predict wall behavior. It also highlights that number of cycles has a significant effect on simulation results.
•Wall behavior in liquefiable soils can successfully be simulated in liquefiable soils.•Initial Condition of toe of the wall should be considered in the tests used for calibration.•Simulation accuracy is dependent on loading cycles for PM4Sand and MD.•MD and PM4Sand models struggle predictions for elements tests with initial shear stress.
Past earthquakes have revealed that damage to sheet-pile walls under saturated conditions is closely linked to excess pore water pressure buildup in the surrounding soil. Nonlinear effective stress ...analysis (ESA) is commonly employed to assess the seismic performance of sheet-pile walls in liquefiable soils, incorporating constitutive models for liquefaction simulation. However, ESA results are sensitive to uncertainties in input parameters, model calibration, and modeling techniques. Dynamic centrifuge tests conducted in the Liquefaction Experiments and Analysis Project (LEAP) offer valuable insights into important response mechanisms and validate ESA. Seven centrifuge tests on a cantilevered sheet-pile wall model showed that liquefaction did not occur in the backfill near the wall due to net seaward wall displacement but did occur farther away. In addition, the mechanism of wall displacement was mainly due to the shear deformation of the softened backfill, with the displacement magnitude depending on the relative density of soil, peak ground acceleration of base motion, and wall displacement during gravity loading. Nonlinear ESA was performed for three centrifuge tests using FLAC2D and the PM4Sand constitutive model for soil. Gravity analysis captured static wall displacement and initial stress distribution in the soil. Two calibrations of the PM4Sand model were pursued at the element level: C1 calibration for liquefaction strength and C2 calibration for liquefaction strength and the post-liquefaction shear strain accumulation rate. System-level simulations showed similar liquefaction behavior as observed in the tests for both calibrations. However, the C2 calibration provided closer predictions of wall displacements, while the C1 calibration (default for PM4Sand) resulted in larger and more conservative displacements. Overall, the PM4Sand model performed well with minimal calibration, making it suitable for nonlinear ESA of sheet-pile walls.
•Seismic performance of sheet-pile walls in liquefiable soils was assessed using centrifuge tests and numerical simulations.•Wall displacement was governed by shear deformation of the backfill due to excess pore water pressure buildup.•Calibration of the rate of post-liquefaction shear strain accumulation improved the predictions of wall displacement.•The default PM4Sand calibration led to conservative predictions of wall displacement.
The Liquefaction Experiments and Analysis Projects (LEAP) organized centrifuge tests and corresponding numerical predictions for the seismic response of sheet-pile wall in liquefiable deposits in ...2022. Within LEAP 2022, two versions of the CycLiq constitutive model, i.e., the original (CycLiq) and modified (CycLiq-M) versions, were calibrated and used for numerical predictions. CycLiq-M was first calibrated using cyclic direct simple shear (CDSS) element tests on the test material, Ottawa F65 sand, and then used for Type-A predictions of another set of CDSS tests for which the results were priorly unknown, validating the model's performance at the element level. Type-B predictions of centrifuge shaking table model tests on sheet-pile wall in liquefiable deposit was then performed using both versions of the calibrated model, without prior knowledge of test results. The results show that the properly calibrated CycLiq model can make reasonable predictions for soil acceleration, excess pore pressure, settlement, and especially sheet-pile wall displacement. In particular, the CycLiq-M version with enhanced cyclic resistance simulation capability exhibits significant improvement in prediction accuracy. Using numerical simulation, the influence of soil-container friction in centrifuge model tests was assessed.
•Rigorous calibration of CycLiq models based on extensive element test.•Good Type-A prediction achieved for undrained cyclic tests on Ottawa F65 sand.•Accurate Type-B prediction achieved for soil and sheet-pile wall response.•Modified version of the models exhibited significantly superior performance.
This study presents numerical simulations of 13 prototype-scale centrifuge tests from the LEAP-2022 project, employing the SANISAND-MSf plasticity model. Calibrated based on data from 56 cyclic ...direct simple shear tests, the objective was to evaluate the model’s ability to capture cyclic liquefaction-related phenomena comprehensively. The adopted calibration strategy balanced the considerations for the challenges posed by asymmetric cyclic shear stress conditions. Two-dimensional plane-strain numerical models were constructed in OpenSees, simulating a sheet-pile wall supporting medium-dense liquefiable sand under seismic excitations. Results demonstrate the model’s proficiency in predicting excess porewater pressure evolution, spectral acceleration, shake-induced settlement, and sheet-pile head displacement. The study also provides insights into deviations in sheet-pile head displacements between experiments and simulations. Challenges in simulating tests EU-1 and KAIST-2 were identified and addressed, with the overprediction in EU-1 attributed to an overestimation of the pace and extent of cyclic liquefaction and in KAIST-2 to the sensitivity of large cyclic deformations to changes in relative density. The findings offer valuable insights for refining constitutive models, underscoring the importance of considering diverse loading conditions to better align with observed system responses.
•The SANISAND-MSf model effectively simulates phenomena related to cyclic liquefaction.•Calibration strategy balanced both symmetric and asymmetric cyclic shearing considerations.•The model is validated with extensive element-level and centrifuge model data from LEAP-2022.•Insights offered for refining cyclic liquefaction modeling under diverse loading conditions.
Analysis of the seismic design of retaining structures is complex due to the intricate interplay between the response of backfill soil and supporting wall. When dealing with liquefiable soils, ...numerical modeling is often employed to gain insight into the mechanisms behind the resulting deformation of retaining walls during earthquakes. This paper focuses on detailed numerical modeling of two well-documented centrifuge tests of such systems from the last two rounds of LEAP, with different embedment ratios and shaking intensities, and their impacts on the system response of the sheet-pile wall supporting a liquefiable submerged deposit. First, a soil constitutive model is calibrated using data from cyclic direct simple shear tests. The two centrifuge models with different wall embedment ratios and shaking intensities are then simulated and used for validation and assessment purposes. The numerical model shows a successful performance in capturing the system response for both models. Assessing details of the stress-strain response in the numerical model reveals two dominant cyclic deformation mechanisms in the backfill soil: cyclic mobility and the accumulation of residual deformation. The success of the adopted numerical approach in capturing the experimental results is attributed to the constitutive model's ability to simulate both of these cyclic deformation mechanisms.
Blind numerical simulations of seven centrifuge tests with “identical” models of a sheet-pile wall supporting medium dense liquefiable backfill and subjected to seismic excitation were performed as ...part of the LEAP 2020 project. The analyses were conducted with FLAC using the Ta-Ger soil constitutive model. The Ta-Ger model parameters were calibrated against available laboratory DSS data on Ottawa sand with similar relative density with a focus on capturing at an element level: i) the liquefaction triggering resistance, ii) the post-liquefaction rate of shear-strain accumulation, iii) overburden effects on liquefaction triggering resistance and iv) realistic shear stress-strain responses. A single numerical model was built in prototype scale and analyses were performed by only varying the input seismic motion recorded at the base of each of seven centrifuge tests. Comparisons of numerical predictions with measured centrifuge test responses indicate that the analyses successfully capture the primary mechanisms of the system response. These included liquefaction in the free-field and development of negative pore pressures behind the wall, with accurate predictions of outward wall displacement for the majority of the tests. Most centrifuge tests and numerical predictions consistently exhibit a systematic linear trend of increase in wall displacements with spectral acceleration at the predominant frequency of the system. The numerical analyses overpredicted wall displacements only for centrifuge tests not following this trend, indicating that the variations maybe due to experimental variations from their specifications that were not considered in the blind predictions.
•Blind numerical simulations predicted the seismic response of a sheet-pile-wall.•Ta-Ger constitutive model was calibrated against CSS lab data on Ottawa F65 sand.•Numerical predictions were compared against centrifuge tests for LEAP 2020 project.•Liquefaction in the free-field and wall outward rotation was captured numerically.•Wall displacement linearly increases with spectral acceleration at 1 Hz.
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