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有限元素法分析加勁擋土牆內加速度放大反應

Finite Element Analyses of Acceleration-Amplified Response within Geosynthetic-Reinforced Soil Structures

作者:唐嘉禧
畢業學校:國立臺灣科技大學
出版單位:國立臺灣科技大學
核准日期:2016-01-14
類型:Electronic Thesis or Dissertation
權限:Copyright information available at source archive--National Taiwan University of Science and Technology....

中文摘要

Finite element analyses were conducted to investigate the acceleration-amplified responses within geosynthetic-reinforced soil (GRS) structures. The focus of this thesis is on the influences of backfill soil and reinforcement parameters on the acceleration responses of GRS structures. Dynamic soil properties (i.e., shear modulus reduction and hysteretic damping) were considered in the soil model of dynamic calculations. Numerical modeling were verified through the experiment database from a dynamic centrifuge GRS embankment model with input ground accelerations of various amplitudes (ag = 0.03- 0.10g). The results showed that the analyzed values of acceleration amplification factor, Am, the ratio of the horizontal acceleration (ah) within the structures to the input ground motion (ag) were predicted well at the middle and the bottom of the model and were underestimated at the top, compared with the measured values. All factors were amplified and were distributed non-uniformly with the structure elevation
Further, a series of parametric studies was conducted to identify the key influential design parameters on the acceleration amplification factor, Am. Parametric studies results indicated that the amplification factors within GRS embankment model were influenced by the dynamic soil properties at small-strains level (G0ref, r0.7, and ξ). The Am value decreased as the initial shear modulus (G0ref) and the damping ratio of Rayleigh damping (ξ) increased. The lesser reduction of shear modulus (increased r0.7 ) also decreased Am. In contrast with soil, the reinforcement ultimate tensile strength (Tult) and axial stiffness (EA) had no influence on the Am. Also, the influences of the aspect ratio (L/H) and the vertical spacing (Sv) of the reinforcement were negligible.

英文摘要

Finite element analyses were conducted to investigate the acceleration-amplified responses within geosynthetic-reinforced soil (GRS) structures. The focus of this thesis is on the influences of backfill soil and reinforcement parameters on the acceleration responses of GRS structures. Dynamic soil properties (i.e., shear modulus reduction and hysteretic damping) were considered in the soil model of dynamic calculations. Numerical modeling were verified through the experiment database from a dynamic centrifuge GRS embankment model with input ground accelerations of various amplitudes (ag = 0.03- 0.10g). The results showed that the analyzed values of acceleration amplification factor, Am, the ratio of the horizontal acceleration (ah) within the structures to the input ground motion (ag) were predicted well at the middle and the bottom of the model and were underestimated at the top, compared with the measured values. All factors were amplified and were distributed non-uniformly with the structure elevation
Further, a series of parametric studies was conducted to identify the key influential design parameters on the acceleration amplification factor, Am. Parametric studies results indicated that the amplification factors within GRS embankment model were influenced by the dynamic soil properties at small-strains level (G0ref, r0.7, and ). The Am value decreased as the initial shear modulus (G0ref) and the damping ratio of Rayleigh damping ( ) increased. The lesser reduction of shear modulus (increased r0.7 ) also decreased Am. In contrast with soil, the reinforcement ultimate tensile strength (Tult) and axial stiffness (EA) had no influence on the Am. Also, the influences of the aspect ratio (L/H) and the vertical spacing (Sv) of the reinforcement were negligible.

 

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