Estimating Deformation Modulus and Bearing Capacity of Deep Soils from Dynamic Penetration Test

The dynamic penetration test (DPT) and the Menard pressuremeter test (PMT) have been widely used in geotechnical survey of deep soils for megadam foundations in western China. The DPT measures are not well utilized due to the lack of correction factors and of empirical relationships for deep soils. This study investigates the relationships between the corrected DPT blow counts (N₁₂₀^′), pressuremeter modulus (EPMT), limit pressure (p_L), deformation modulus (E₀), and bearing capacity (f_ak) derived from the PMT results. Meanwhile, a nonlinear regression model is developed to predict the DPT correction factor (a) based on the raw DPT blow counts (N₁₂₀) and the rod length (L) by integrating the available correction factors for shallow gravelly soils suggested by the code provisions and the deep soil data in this work. It is concluded that the proposed DPT correction factors match well with the code suggestions and the new compiled dataset, and the corrected DPT blow counts can be used to reasonably predict the engineering properties of deep sand and clay soils. Although the proposed correlations need to be tested among different soil types and regions, the results shed the light on in situ geotechnical tests and data utilization for deep and thick overburden.

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