Abstract: The wetting deformation test on the large specimens of gravelly soil core wall material is a challenging task, because the physical properties of gravelly soil material lead to difficulties of saturation, consolidation and drainage for a specimen and a long test cycle. In this study, we tackled the above key issues from the aspects of test technology and test methods, analyzed and corrected the deviation of test results in previous research, and performed detailed exploration in the aspects of large discreteness of the wetting deformation of gravelly soil and the problem of stress saturation. Through strict control of key details such as volumetric deformation correction, water inflow correction, real-time saturation calculation and discrete processing of results in the process of wetting test, the wetting deformation test on the typical gravelly soil materials was successfully completed and reasonable wetting deformation results were obtained. Abnormal phenomena in the test, such as overall upward deformation of the triaxial pressure chamber during the application of confining pressure and no obvious wetting deformation under high stress, have been reasonably explained through data and theoretical analyses. The understanding of geotechnical test technology and wetting deformation of gravelly soil materials has been deepened.

Key words: gravelly soil core material, wetting deformation, single-line method, large-scale triaxial test, test technology