scholarly journals Shear-wave velocity and site-amplification factors for 50 Australian sites determined by the spectral analysis of surface waves method

Author(s):  
Robert E. Kayen ◽  
Bradley A. Carkin ◽  
Trevor Allen ◽  
Clive Collins ◽  
Andrew McPherson ◽  
...  
2005 ◽  
Vol 21 (1) ◽  
pp. 1-30 ◽  
Author(s):  
Yoojoong Choi ◽  
Jonathan P. Stewart

We develop empirical relationships to predict nonlinear (i.e., amplitude-dependant) amplification factors for 5% damped response spectral acceleration as a continuous function of average shear wave velocity in the upper 30 m, Vs-30. We evaluate amplification factors as residuals between spectral accelerations from recordings and modified rock attenuation relationships for active regions. Amplification at low- and mid-periods is shown to increase with decreasing Vs-30 and to exhibit nonlinearity that is dependent on Vs-30. The degree of nonlinearity is large for NEHRP Category E (Vs-30<180 m/s) but decreases rapidly with Vs-30, and is small for Vs-30>∼300 m/s. The results can be used as Vs-30-based site factors with attenuation relationships. The results also provide an independent check of site factors published in the NEHRP Provisions, and apparent bias in some of the existing NEHRP factors is identified. Moreover, the results provide evidence that data dispersion is dependent on Vs-30.


1999 ◽  
Vol 36 (2) ◽  
pp. 291-299 ◽  
Author(s):  
D S Kim ◽  
H C Park

In order to assess the quality and depth of ground densification due to compaction, standard and (or) cone penetration tests are often performed before and after compaction. Both methods are intrusive and one-location tests and require a substantial amount of time to evaluate a large area, and evaluation quality is quite dependent on the operation technique and soil type. In this paper, the quality and extent of ground densification by compaction were evaluated using the results from in situ spectral analysis of surface waves (SASW) tests and laboratory resonant column (RC) tests. The SASW test was used to determine the shear wave velocity profiles before and after compaction, and the RC test was adopted to determine the correlation between the normalized shear wave velocity and density of the site, which is almost independent of confinement. Testing and data-reduction procedures of both tests were discussed, and a simplified procedure for evaluating ground densification was proposed by effectively combining in situ shear wave velocity profiles determined by SASW tests with the correlation between normalized shear wave velocity and density determined by RC tests. Finally, the feasibility of the proposed method was verified by performing field studies at the Inchon International Airport project. Field densities determined by the proposed method matched well with those determined by sand cone tests.Key words: density evaluation, densification, compaction, shear wave velocity, spectral analysis of surface waves test, resonant column test.


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