Liquefaction evaluation on sand-like gravelly soil deposits based on field Vs measurements during the 2008 Wenchuan earthquake

During the 2008 Wenchuan earthquake, extensive liquefaction of sand-like gravelly soil deposits was observed over an area of about 500 × 200 km². Since gravel content significantly affects the stiffness and liquefaction resistance of gravelly soils, it has become an ongoing challenge for engineers to reliably and cost-effectively assess the liquefaction resistance of such soil deposits with different gravel contents. To this end, the procedures for consistently assessing the liquefaction resistance of sand-like gravelly soils were first put forward based on the previously proposed improved CRR-V_s1 characterization model for binary mixtures, which converts the liquefaction evaluation of sand-like gravelly soils into the assessment of liquefaction resistance of the base sand matrix with an equivalent stiffness. Then, in-situ gravelly soils sampled from the earthquake-impacted area were tested to parameterize the proposed characterization model. Lastly, liquefaction case histories of gravelly soils compiled during the 2008 Wenchuan earthquake were recompiled and restudied to validate the performance of the proposed characterization model. Typical liquefaction case history studies show that the proposed characterization model successfully predicts the severe liquefaction hazard at the Banqiao school site and the marginal liquefaction phenomenon at the Jiangyou thermal power plant site. Comparisons between the proposed characterization model and the 54 recompiled liquefaction case history datasets demonstrate that the proposed characterization model can accurately discriminate both the liquefied and non-liquefied case histories. These validation results in turn suggest that the proposed characterization model is highly feasible for engineering applications on a regional scale covering various gravel contents.