Noninvasive shear wave velocity (SWV) profiling of soil deposits has long been recognized as a cost-effective approach to obtain SWV data essential for seismic response analysis including site amplification and liquefaction. The controlled-source measurement of surface wave dispersion (CXW) is a relatively new noninvasive method that is used for site characterization in the United States, Japan, and other countries. The CXW method uses harmonic-controlled sources to produce steady state Rayleigh waves in order to measure the dispersion characteristics of soil and rock. Several interpretation techniques may be used to obtain SWV structure from Rayleigh wave dispersion data (in a process that is referred to as the Vf-VS method). CXW measurement data from more than 200 soil and rock sites were analyzed. These results were used to formulate a new approach for the Vf-VS interpretation method based on the new concept of reference profiles that describes the average dispersion curve and SWV structure. The refere...

New Approach to Interpretation of Noninvasive Surface Wave Measurements for Soil Profiling

Accurate shear wave velocity profiles have been long recognized as essential data to evaluate the dynamic response of soil deposits and soil-structure interaction under earthquake and other forms of dynamic loading. The determination of shear wave velocity profiles is especially important for port design in seismically active locations. The advantage of obtaining shear wave velocity profiles by in situ non-intrusive surface wave measurements, especially in hard-to-sample soils, has been well recognized. The paper presents the controlled source spectral analysis of surface waves (CSSASW) system which uses a controlled vibration source that generates 'random' pulses. The 'raw' Rayleigh wave phase velocity dispersion data are used to compute shear wave velocity distribution in depth to produce a layered soil profile. Other soil properties may be obtained from the shear wave velocity profile based on available correlations. Recently, the CSSASW system was used for soil profiling in the World Port of Los Angeles. At a large fill area in the port CSSASW results clearly identify the distinct soil layers and show good agreement with available soil data from SPT and CPT borings.

Maria C. Arbelaez

Papers

Non-intrusive rayleigh wave measurement system for soil profiling in ports