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This paper proposes a frequency wavenumber-finite element hybrid method with kinetic source model for dynamic analysis of pile founded nuclear island from fault to structure. This method benefits from the effective synthesis of broadband ground motions by the fault source model, the realism of frequency wavenumber for earthquake simulation from fault to the site and the mesh refinement capabilities of the finite element in modeling the nuclear structure and the near soil. This method achieves the expression of source rupture, wave propagation, site response, soil-structure interaction, soil nonlinearity and structure response accurately, which solves the multi-scale problem from crustal layer to nuclear structure. Under finite-fault excitation, the correctness of the proposed method is validated by comparing with the frequency wavenumber method. Then, a full process seismic simulation of a pile founded nuclear island built on a non-rock site is conducted. The influence of source parameter and soil-structure interaction is studied. Results indicate that the change of source parameter can lead to difference nuclear island failure direction. With the increase of dip angle, the appearance of maximum stress is in advance. The soil nonlinearity could greatly amplify the soil-structure interaction effect and the loads on piles. The connection between the containment vessel and the raft is vulnerable and the piles on the edge of the raft is prone to damage. This hybrid method could accomplish an appropriate seismic evaluation of the nuclear structures and the conclusions may provide reference for seismic design of nuclear structure.

期刊论文 2025-08-01 DOI: 10.1016/j.soildyn.2025.109419 ISSN: 0267-7261

As the monopile supported offshore wind turbine (OWT) is a dynamic sensitive structure, one of the major challenges in its design is the assessment of the natural frequency to avoid resonance during the lifetime. Since the characteristics of OWTs under dynamic loading and their long-term behavior are not fully understood, to study their natural frequency considering soil-monopile interaction, a series of scaled model tests in sand were performed. The first part was about the initial resonant frequency subjected to different forcing amplitudes and the second part was about the change of the natural frequency under long-term horizontal cyclic loadings. Based on the test results, the effects of pile-soil interaction, related to the loading amplitude, embedment depth, soil density, and cyclic numbers, on the natural frequency of OWTs are presented by a non-dimensional group based on the explanation of the governing mechanism. As the soil nonlinearity leads to a degradation in the natural frequency of monopile supported OWTs in the sand and the cyclic loading results in an increase, the choice of the natural frequency closer to the upper limit of the 1P band is suggested in practice based on the tradeoff of the two above effects.

期刊论文 2025-05-15 DOI: 10.1016/j.oceaneng.2025.120913 ISSN: 0029-8018

This work proposes a novel plastic damage model to capture the post elastic flow-controlled damages in pavement-soil systems prescribed by the vibrations of moving load. Initially, the pavement structure has been modelled as a single-layer system resting on a spring-dashpot system representing soil mass. Then, multilayer modelling was adopted to analyze the post-elastic dynamic response in supporting plastic flow-controlled layers of geomaterial. Three mechanistic zones namely, elastic recoverable, transition, and post elastic zone have been conceptualized to identify the damage. The nonlinearity in stress and equivalent plastic strain has been observed for the set of selected velocities and load intensities specified in codal provisions. The variation in equivalent plastic strain is observed in the range of 10-16 to 10-3% in the granular base layer and 10-16 to 10-4% in the subgrade soil layer. The findings show that the equivalent plastic strain due to plastic flow prescribed by the vibrations of moving action of vehicular load at varied velocities is one of the root causes of permanent deformations. The propagation of dynamic load vibrations from the uppermost layer of pavement induces the generation of stress waves within distinct sub-layers of geomaterial. Hence, the observed behaviour leads to the generation of nonlinear stress waves prescribed by a vibrational mechanism of stress transfer (VMST). Therefore, the evaluation of the nonlinearities causing damage in pavement structure supported by flow controlled geomaterials has the potential to predict permanent deformations and its implications in the design of pavements supporting the transportation network.

期刊论文 2025-05-01 DOI: 10.1016/j.ijnonlinmec.2025.105045 ISSN: 0020-7462

The impact of site effects on ground motion is a critical factor for earthquake disaster prevention and mitigation, as these effects can amplify ground motion and affect building fragility. On February 6, 2023, southeastern Turkey was struck by two strong earthquakes, with magnitudes of Mw7.7 and Mw7.6, followed by numerous aftershocks. These events resulted in severe casualties and substantial economic losses. Field investigations revealed severe damage to mid-rise and high-rise buildings in Kahramanmara & scedil; and Antakya. Both cities are located in valley regions, which are particularly susceptible to earthquake damage due to the amplification of ground motion caused by soft soil conditions and valley topography. In this paper, Horizontal-to-Vertical Spectral Ratio (H/V) technique is used to decipher how site effects affect ground motion and damage using the strong motion records. The analysis revealed that the predominant frequency of ground motion decreases near the valley areas and increases toward the hill slopes. These spatial variations in predominant frequency have significant implications for building safety. Structures located in areas where the predominant frequency matches their natural frequency are more prone to resonance effects, significantly increasing the risk of damage during seismic events. Additionally, the study found that the nonlinearity of the site conditions amplified the acceleration response spectrum at a period of 1 s. This amplification exceeded the local structural design capacity. The findings indicate that site effects can significantly intensify earthquake damage in Kahramanmara & scedil; and Antakya by amplifying ground motion and increasing the vulnerability of mid-rise and high-rise structures.

期刊论文 2025-04-01 DOI: 10.1007/s12665-025-12103-9 ISSN: 1866-6280

Shallow failures often occur in earthen sites. The nonlinear strength criteria of silt and their correlation with dry-wet cycles are necessary for evaluation of failure problems of earthen site exposed to natural environments, such as rainfall and evaporation. Thus, in this study, a designed soil column and method in line with the natural environment characteristics of earthen sites were adopted to study the effects of the number of dry-wet cycles on the shear mechanical properties of the site silt under consolidated undrained triaxial conditions. The results show that the strength of silt and its parameter, cohesion c, do not monotonically decrease with the number of dry-wet cycles but exhibit a trend of initially increasing and then decreasing. The nonlinear characteristics of the strength of silt are remarkable, particularly in the range of small normal stresses. Based on Baker's generalized power law strength criterion, a nonlinear strength criterion considering the number of dry-wet cycles of silt was established with the parameter A of the strength criterion initially increasing and gradually decreasing and the value of N essentially unchanged. The improved Duncan-Chang model considering the dry-wet cycle effect and strength nonlinearity of silt in earthen sites was presented and verified. The research can offer significant theoretical support for the analyses of shallow collapses and other issues related to failure problems of earthen sites.

期刊论文 2025-04-01 DOI: 10.1007/s10706-025-03118-x ISSN: 0960-3182

Understanding the shear behaviors of expansive soils under a wide range of confining pressures 6 3 is crucial for effectively managing their shallow hazards, especially at low 6 3 values. The shear behaviors of expansive soils under the low 6 3 values exhibit significant differences with those under the high 6 3 values, which have been inadequately addressed in existing research. This paper investigated the shear behaviors of two expansive soils across a wide range of 6 3 values (i.e., 15-400 kPa) through consolidated undrained triaxial tests. The results showed a significant nonlinear relationship between the shear strength and 6 3 , particularly at the low 6 3 values. The nonlinearity of shear strength versus 6 3 in shallow expansive soils was described by a modified power function. As 6 3 decreased, both the brittleness index 7 and curvature K increased nonlinearly. Comparisons between the tangent method, based on the modified power function, and the K f method, based on the Mohr- Coulomb criterion, suggested that neglecting the nonlinearity of shear strength versus 6 3 led to overestimations of the cohesion and underestimations of the internal friction angle at low 6 3 values, and the reverse trend was observed at high 6 3 values. The magnitude of these deviations depended on both the shear strength nonlinearity and the selected 6 3 values. The findings presented herein are helpful for the mitigation of shallow hazards in roadbeds, slopes, and foundation engineering associated with expansive soils.

期刊论文 2024-09-01 DOI: 10.1016/j.trgeo.2024.101328 ISSN: 2214-3912

This study established a numerical model for soil-structure interaction (SSI) to examine the effects of the spatial incidence angle of SV waves and soil nonlinearity, utilizing viscoelastic artificial boundaries (VAB) and equivalent nodal force (ENF) method. Both the foundation's and superstructure's torsion and rocking responses were then analyzed. The findings indicate that subjected to spatially oblique incident SV waves, the rectangular foundation primarily has the rocking response while the torsional response is negligible. Furthermore, the maximum torsional and rocking angles about the x-axis at each frame floor are significantly enlarged by comparison with the perpendicular incident case. Moreover, the soil nonlinearity could increase the foundation's rocking angle and enlarge the maximum torsion and rocking responses of the structure's floors. Consequently, structural seismic damage assessment requires considering both the soil nonlinearity and incident seismic wave angles.

期刊论文 2024-09-01 DOI: 10.1016/j.soildyn.2024.108868 ISSN: 0267-7261

Tunnels subjected to active fault dislocation may experience significant damage. This paper establishes a novel methodology and solution procedure for analyzing the mechanical response and failure characteristics of tunnels subjected to active fault dislocation based on an elastic foundation beam model. The proposed methodology includes axial, transverse, and vertical soil-tunnel interaction terms, in addition to geometrical nonlinearity and axial force terms in the governing equation. This approach has a significantly extended application range, effectively addressing the problems encountered in tunnels crossing active faults with diverse crossing angles, dip angles, and fault types. The proposed methodology is verified by comparison to a 3D FEM model with various fault types, experimental tests, and on-site case, and the results are in excellent quantitative and qualitative agreement with the numerical, experimental, and on-site results. When fault displacement is below 0.5 m, disregarding geometric nonlinearity results in calculation errors of approximately 10% to 17% for peak axial force (Nmax), 18% to 22% for peak shear force (Vmax), and 20% to 30% for peak bending moment (Mmax). Finally, the responses caused by different factors, i.e., fault type, fault displacement, tunnel stiffness, and tunnel diameter, are investigated in detail to better understand tunnels crossing active faults. The results show that amongst the various fault types, the Vmax and the Mmax experienced by tunnels subjected to oblique slip-fault dislocation surpass those of other fault types, accompanied by the most extensive failure range. The augmentation of fault displacement, tunnel stiffness, and tunnel diameter precipitates a corresponding escalation in the Nmax, Vmax, Mmax, and failure range. Under oblique-slip fault dislocation, the tunnel undergoes an initial phase of shear failure, followed by tension-bending failure, delineated by distinct fault displacement thresholds of 0.1 m and 0.2 m, respectively. The proposed methodology provides the advantage of reliable stability analysis and design of tunnels crossing active faults.

期刊论文 2024-06-01 DOI: 10.1016/j.istruc.2024.106583 ISSN: 2352-0124

The large strain and nonlinear consolidation characteristics of soft soils with high compressibility have obvious effects on their consolidation, but few analytical solutions for large-strain nonlinear consolidation of soils with vertical drains have been reported in the literature. By considering the large deformation characteristics of soft soils with high compressibility during consolidation, a large-strain nonlinear consolidation model of soils with vertical drains is developed and an analytical solution for this consolidation model is obtained based on Gibson's large deformation consolidation theory, in which a double logarithmic nonlinear compressibility and permeability model is adopted to describe the variation of the compressibility and permeability of soft soils. The proposed analytical solutions are compared with the numerical solutions of large-strain nonlinear consolidation of soils with vertical drains and the analytical solutions of small-strain linear consolidation under specific conditions to verify its reliability. On this basis, the nonlinear consolidation properties of soils with vertical drains under different conditions are analyzed by extensive calculations. The results show that the consolidation rate increases with decreasing the permeability parameter alpha, when the compression index I-c, keeps constant. The consolidation rate increases with decreasing the compression index I-c, when the permeability parameter alpha remains constant. The consolidation rate of soils with vertical drains increases with an increase in external load, and decrease with an increase in the ratio of influential zone radius to vertical drain radius when the compressibility and permeability parameters remain constant. Finally, the proposed analytical solution is applied to the reclaimed foundation treatment project of Shenzhen Western Corridor boundary control point(BCP). The settlement curve calculated by proposed solutions is in good agreement with the measured curve, which further illustrates the engineering applicability of the proposed analytical solution.

期刊论文 2024-05-01 DOI: 10.16285/j.rsm.2023.0852 ISSN: 1000-7598

Tunnels crossing active faults are susceptible to severe damage. This study establishes an improved semianalytical methodology for analyzing the mechanical responses of tunnels subjected to active fault dislocation. The methodology incorporates nonlinear axial, transverse, and vertical soil-tunnel interactions, shear effects, and geometric nonlinearity within its governing equations. Compared with existing methods, the proposed method has a significantly extended application range with improved accuracy, and the solution procedure demonstrates exceptional computational efficiency, with each case typically being solved in less than 1 s. The proposed methodology demonstrates outstanding qualitative and quantitative agreement with 3D FEM results across various fault types, as well as with the results obtained from the model test. Additionally, neglecting shear effects results in approximately 1.11 to 1.20 times higher bending moments and 1.13 to 1.19 times higher shear forces of the tunnel. Finally, a parametric analysis was conducted based on the proposed methodology to investigate the influence of critical parameters, such as fault displacement, buried depth, tunnel diameter, soil cohesion, and soil friction angle, on the tunnel response under fault dislocation. The results suggest that the tunnel responses positively correlate with the fault displacement, buried depth, and soil cohesion. Increasing the fault displacement amplifies the vertical shear force and bending moment asymmetry while increasing buried depth reduces this asymmetry. An increase in the tunnel diameter and soil friction angle is associated with a decrease in the peak axial force and an increase in the vertical shear force and bending moment. Additionally, variations in the friction angle do not exert a significant effect on the transverse shear force and bending moment.

期刊论文 2024-04-01 DOI: 10.1016/j.tws.2024.111561 ISSN: 0263-8231
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