Evaluation and Optimization of Dynamic Cone Penetration test (DPT) for Assessment of Liquefaction in Gravelly Soils

The dynamic cone penetration test (DPT) developed in China has been correlated with liquefaction resistance in gravelly soils based on field performance data from the Mw7.9 Wenchuan, China earthquake. The DPT consists of a 74 mm diameter cone tip driven by a 120 kg hammer with a free fall height of 1 m. To expand the data base, DPT soundings were performed at the Pence Ranch and Larter Ranch sites where gravelly soil liquefied during the 1983 Mw6.9 Borah Peak earthquake. DPT testing was performed using an automatic hammer with the energy specified in the Chinese standard and with an SPT hammer. In general, comparisons suggest that standard energy corrections developed for the SPT can be used for the DPT. The DPT correctly predicted liquefaction and non-liquefaction at these two test sites. Liquefaction resistance from the DPT (30% probability) also correlated reasonably well with that from Becker penetration testing (BPT).