Finite Element Method Accuracy for Wave Propagation Problems

Kuhlemeyer, Roger L.; Leth, John

doi:10.1061/jsfeaq.0001885

Cited by 938 publications

(176 citation statements)

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“…e grid increases in size away from the charge, but it should be shorter than 1/8∼1/10 of the wavelength in general to properly reduce any wave distortions [23]. ere are a total of 317,456 elements and 428,532 nodes in the numerical simulation.…”

Section: E Numerical Tool and Equivalent Freezing Simulationmentioning

confidence: 99%

Investigation and Control of the Blasting‐Induced Ground Vibration under Cold Condition

Yang

Yao

et al. 2021

Shock and Vibration

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This paper focuses on the investigation and control of the blasting-induced ground vibration under cold condition. The mechanical performance and wave propagation characteristics of the frozen rock mass are quite different from that of the conventional condition. Laboratory tests were implemented to investigate the wave impedance of rock mass in the frozen, saturated, normal, and drying states. Results reveal the longitudinal wave velocity could be enlarged by 40 percent in the frozen state. Then long-term monitoring of blasting vibration was implemented based on the blasting excavation of the Fengman hydropower station reconstruction project in the north of China. Results demonstrate the PPV and frequency both attenuate much slower when the rock mass is frozen, and the obvious turning points of PPV could be found between different temperatures, where the change of the PPV relationship happens. At last, numerical simulation of the blasting seismic wave attenuation and the response in the protected structure was implemented. The equivalent freezing simulation method was proposed and verified with the site experiment data. Results demonstrate that the attenuation coefficient decreases obviously as the frozen depth of the rock mass increases. The dynamic degree response in structure is much stronger and the maximum charge weight per delay was limited more strictly under the frozen condition. A most adverse frozen depth was determined when the charge weight per delay gets the minimum value. With the above control approaches, a total of 676 blasting was completed in Fengman hydropower station reconstruction and no case of excessive measurement could be found.

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Section: E Numerical Tool and Equivalent Freezing Simulationmentioning

confidence: 99%

Investigation and Control of the Blasting‐Induced Ground Vibration under Cold Condition

Yang

Yao

et al. 2021

Shock and Vibration

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“…According to Kuhlemeyer and Lysmer [23] to accurately represent the wave transmission through a model, the spatial element size, Δl, should be smaller than approximately one-tenth to one-eighth of the input wavelength associated with the highest frequency of the input wave.…”

Section: Modeling Proceduresmentioning

confidence: 99%

Effect of Foundation Flexibility on the Seismic Performance of a High-Rise Structure under Far-Field and Near-Field Earthquakes

2021

IJE

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In this study, the seismic performance of a 20-storey steel structure with a mat foundation located on layered soil is investigated under an array of strong ground excitations, which includes 6 far-fault and 6 near-fault earthquakes. Eight different modes for soil layering have been considered in the numerical simulation. FLAC 2D nonlinear platform has been used to model the near-realistic behavior. To this end, hundred lines of codes and subroutines have been developed in this platform to perform the analysis. The results of the analyzes include the absolute displacement of the floors, the ratio of the relative displacement of the floors, the shear force, the axial force, and the bending moment of the columns. It was concluded that for a 20-story structure on a mat foundation under both far-field and near-field earthquakes, the most reliable type of soil is the dense sandy soil and the most critical case is the soft clay soil. It was also observed that the near-field strong ground motions have imposed more critical structural responses compared to far-field records.

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“…Therefore, the anchors' pre-tensioning load was set to 450 kN for all anchors in the design was scaled to 150 kN for 10 meter-height excavations due to 3 meters horizontal spacing of anchors and 180 kN for 20 m excavations due to 2.5 m meters horizontal spacing. Kulhemeyer and Lysmer (1973) [18] suggested that zone dimensions in a finite difference analysis be one-tenth to one-eighth of the input wavelength's highest frequency component for proper wave propagation in dynamic analyses. In the present study, the wavelength for H-1 and H-2 harmonic loads were 55 and 46.87 meters, respectively; hence the dimensions of the zones are 25 cm, and 50 cm in the models of 10m and 20m are qualified for the proper wave propagation condition for both models.…”

Section: Model Descriptionmentioning

confidence: 99%

Performance of Ground Anchored Walls Subjected to Dynamic and Pseudo-Static Loading

2021

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This study investigates the response of pre-stressed anchored excavation walls under dynamic and pseudo-static loadings. A finite difference numerical model was developed using FLAC2D, and the results were successfully validated against full-scale experimental data. Analyses were performed on 10, and 20-m-height stabilized excavated slopes with 60° to 90° of inclination angle with the horizon to represent an applicable variety of wall geometries. In dynamic analysis, the statically stabilized models were subjected to 0.2 to 0.6g of the dynamic peak acceleration to evaluate the effect of ground acceleration on their performance. Furthermore, pseudo-static analyses were performed on the statically stabilized models with pseudo-static coefficients ranging from 0.06 to 0.22. The results revealed that ground anchored slopes generally showed acceptable performances under dynamic loading, while higher axial forces were induced to ground anchors in higher and steeper models. Furthermore, comparing the results of dynamic and pseudo-static analyses showed a good agreement between the two methods' predictions in the mobilized axial force along the ground anchors. Pseudo-static coefficients were then proposed to replicate dynamic results, considering the slope geometry and dynamic load peak acceleration. The results revealed that higher and steeper stabilized slopes required higher values of pseudo-static coefficients to match the dynamic predictions successfully. The results indicate that pseudo-static coefficient tend to increase with the increase in dynamic load peak acceleration in any given model. Doi: 10.28991/cej-2021-03091703 Full Text: PDF

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Finite Element Method Accuracy for Wave Propagation Problems

Cited by 938 publications

References 0 publications

Investigation and Control of the Blasting‐Induced Ground Vibration under Cold Condition

Investigation and Control of the Blasting‐Induced Ground Vibration under Cold Condition

Effect of Foundation Flexibility on the Seismic Performance of a High-Rise Structure under Far-Field and Near-Field Earthquakes

Performance of Ground Anchored Walls Subjected to Dynamic and Pseudo-Static Loading

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