Study on evaluation method for soil sample disturbance based on normalized shear modulus

Among various existing methods for evaluating soil sampling disturbance, only the modified volumetric compression method can independently reflect the influence of soil structural damage on the degree of sampling disturbance, while the disturbance degrees obtained by other methods are all comprehensive representations of both stress level and structural damage. This paper proposes a soil sample disturbance evaluation method based on normalized shear modulus. Besides decoupling the effects of soil stress level and structural damage to independently characterize the degree of soil structure damage, this method can also evaluate the disturbance degree of soil samples after experimental operation and consolidation in the testing apparatus. It enables the tracking of structural parameters of soil samples throughout the process from sampling and sample preparation to consolidation under the in-situ stress conditions, and quantitatively assesses the disturbance degree at each stage, thus achieving a full-process disturbance evaluation. The research results show that the error between the sampling disturbance evaluation results obtained by the "normalized stiffness method" and those by the "modified volumetric compression method" is basically within 5%, indicating that the evaluation of sampling disturbance using normalized stiffness is reasonable and effective; the disturbance degree of soil samples will further increase after experimental operation and consolidation, with an increase of approximately 7%~15% compared with that before sample preparation.