1 / 26

NCREE Ming-Hung Chen* NCU Kuo-Liang Wen NTU Chin-Hsiung Loh

U.S.-Taiwan Workshop on Soil Liquefaction. Experience of Suspension P-S Logging Method and Empirical Formula of Shear Wave Velocities in Taiwan. NCREE Ming-Hung Chen* NCU Kuo-Liang Wen NTU Chin-Hsiung Loh USC Robert L. Nigbor. INTRODUCTION.

Download Presentation

NCREE Ming-Hung Chen* NCU Kuo-Liang Wen NTU Chin-Hsiung Loh

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. U.S.-Taiwan Workshop on Soil Liquefaction Experience of Suspension P-S Logging Method and Empirical Formula of Shear Wave Velocities in Taiwan NCREE Ming-Hung Chen* NCU Kuo-Liang Wen NTU Chin-Hsiung Loh USC Robert L. Nigbor

  2. INTRODUCTION • Nearly 700 free-field strong motion stations were set in Taiwan • Since 2000, National Center for Research on Earthquake Engineering (NCREE) collaborated with Central Weather Bureau (CWB) in site investigating.

  3. ●investigated ▲unfinished

  4. INTRODUCTION • Nearly 700 free-field strong motion stations were set in Taiwan • Since 2000, National Center for Research on Earthquake Engineering (NCREE) collaborated with Central Weather Bureau (CWB) in site investigating. • Suspension P-S Logging method was executed in this project

  5. INTRODUCTION (cont’d) • Lots of measuring in soil, gravel and rock layers were experienced • Based on the abundant and reliable shear wave velocities, an empirical formula for alluvial deposits was developed • For some specific sites, surface wave test, seismic refraction test and downhole velocity test were also executed

  6. CHARACTERISTICS OF SUSPENSION P-S LOGGING METHOD • The entire probe in lowered into the borehole filled with water • The separation of the two receivers is one meter • Average wave velocity is determined by inversion of the wave travel time between the two receivers.

  7. B A C D CHARACTERISTICS OF SUSPENSION P-S LOGGING METHOD (cont’d) • Path A – surface wave and seismic refraction • Path B – downhole and uphole • Path C – crosshole • Path D – suspension P-S logging

  8. CHARACTERISTICS OF SUSPENSION P-S LOGGING METHOD (cont’d) • receiver-to-receiver, R-R method • source to receiver, S-R method • Plot all records together to be the depth sequence

  9. P-wave

  10. S-wave

  11. CHARACTERISTICS OF SUSPENSION P-S LOGGING METHOD (cont’d) Spectrum of different layers Clay Vs=263 m/sec l  0.44 m Sand Vs=270 m/sec l  0.54 m Gravel Vs=358 m/sec l  0.30 m Rock Vs=1176 m/sec l  0.67 m

  12. CHARACTERISTICS OF SUSPENSION P-S LOGGING METHOD (cont’d) I: P- wave appears in S-wave recordII,III: S-wave appears in P-wave record

  13. EMPERICAL FORMULA OF SHEAR WAVE • 45 boreholes locate in southwestern alluvium plain area of Taiwan

  14. YunLin ChiaYi TaiNan

  15. EMPERICAL FORMULA OF SHEAR WAVE • 45 boreholes locate in southwestern alluvium plain area of Taiwan • Two major factors: SPT-N value & depth

  16. EMPERICAL FORMULA OF SHEAR WAVE • 45 boreholes locate in southwestern alluvium plain area of Taiwan • Two major factors: SPT-N value & depth • Proposing form: vs = c1+ c2·z+ c3·N1 • N1= corrected N value to a standard σ’= 1 kg/cm2…………….….Liao & Whitman

  17. EMPERICAL FORMULA OF SHEAR WAVE • 45 boreholes locate in southwestern alluvium plain area of Taiwan • Two major factors: SPT-N value & depth • Proposing form: vs = c1+ c2·z+ c3·N1 • vs = c1+4.09·z+ c3·N1

  18. EMPERICAL FORMULA OF SHEAR WAVE • 45 boreholes locate in southwestern alluvium plain area of Taiwan • Two major factors: SPT-N value & depth • Proposing form: vs = c1+ c2·z+ c3·N1 • vs = c1+4.09·z+ c3·N1 • vs = 139.1 + 4.09·z + 2.0415∙N1

  19. PREDICTED AND MEASURED SHEAR WAVE VELOCITIES

  20. COMPARISON WITH OTHER TESTS

  21. CONCLUSION • Very high-resolution data reliably for suspension P-S logging method • More than 200 boreholes have been tested • Materials are classified into three layers as soil, rock and gravel • Empirical formula of shear wave velocity is available in terms of drilling depth and corrected SPT-N values

More Related