Abstract: Coarse-grained soil, the primary material used in the filling of earth-rock dams, consists of particles with a maximum size reaching meter-level. However, indoor tests only allow for downscaled samples. Shrinking the scale while ensuring that the indoor test results accurately reflect the mechanical characteristics of the actual material has always been a challenge in the research of earth-rock dams. Despite significant progress in the research of downscaling methods for coarse-grained soil and their effectiveness in recent years, disagreements still exist in some specific aspects. We made a comprehensive summary and analysis of the existing methods for downscaling coarse-grained soil, as well as the boundary effects and scale effects in sample testing. Scholars in Changjiang River Scientific Research Institute present a method of downscaling coarse-grained soil by determining the density of specimens according to pressuremeter modulus equivalent to that of the actual material, which is called the method of “Equivalent Pressuremeter Modulus to Determine Density”. We further elucidate the relationship between equivalent pressuremeter modulus and consistency in mechanical properties, and expound the theoretical foundation of this method,providing technical support for researching the downscale methods for coarse granular soil.

Key words: coarse granular soil, grade scaling, control standards for degree of compaction, boundary size effect, equivalent density method based on pressuremeter modulus