State‐Equivalent Compaction of Dam Rockfill: Experimental Method, Constitutive Formulation and Numerical Case Study

ABSTRACT This study demonstrates that the pressuremeter modulus can serve as a practical state descriptor for rockfill and can be used directly in constitutive analysis. Large‐scale pressuremeter model tests on two gradations established a clear, monotonic relation between pressuremeter modulus and dry density. Using this relation, densities corresponding to target moduli of 75 and 90 MPa were selected for drained triaxial tests. The results reveal an equal‐modulus equivalence for the two scaled gradations tested: once specimens are compacted to the dry densities corresponding to the same pressuremeter modulus, their stress–strain and volumetric responses become practically indistinguishable across these gradations. These conclusions are drawn from tests on only two scaled materials derived from the same prototype rockfill, so the observed equivalence should not yet be regarded as universal. Building on this finding, we integrate the pressuremeter modulus into a standard hypoplastic formulation through a minimal two‐part enhancement: a state normalisation of the density measure and a stiffness‐scale alignment, achieved by scaling the granular hardness parameter in proportion to the measured modulus. The tensorial structure and calibrated constants of the reference model remain unchanged; only zone‐wise state inputs derived from field or laboratory modulus are required. With one parameter set calibrated at 75 MPa, the framework reproduces element tests at both target moduli and is implemented in a three‐dimensional embankment model of the 298 m Lianghekou rockfill dam. Predicted settlement profiles during staged construction closely match monitoring, capturing both the magnitude and the curvature of the settlement troughs and the observed flattening in zones that achieved higher modulus. A baseline analysis without modulus‐based normalisation shows systematic bias, underscoring the value of the proposed integration.