Theoretical analysis of OCR on sampling disturbance in soils with varying plasticity
Theoretical analysis of OCR on sampling disturbance in soils with varying plasticity
The significant influence of sampling disturbance on measured soil properties makes accurate sample quality assessment essential in geotechnical engineering. This study investigates the effects of the overconsolidation ratio (OCR) on sample quality evaluation of disturbed soils with varying plasticity index (PI) through constitutive element simulations. A unified elastoplastic constitutive model was employed to simulate different disturbance scenarios, including Best Practice Disturbance (BPD) and a modified Ideal Sampling Approach (ISA), with sample quality quantified by the post-disturbance volumetric indicator (e/e0). Complementary laboratory triaxial and oedometer tests were conducted on soil mixtures to determine their constitutive parameters and validate the model's reliability. The results demonstrate that the relationship between e/e and PI is not intrinsic, but is governed by the competing mechanisms of two factors: the soil's susceptibility to disturbance and its compressibility (or initial stiffness). High-PI soils exhibit low susceptibility to disturbance but high compressibility, whereas low-PI soils exhibit the opposite behaviour. An increase in OCR reduces a soil's susceptibility to disturbance while enhancing its stiffness. The trends of e/e0-PI for soils across a wide OCR range were predicted. By identifying OCR as the pivotal factor that shifts the dominance between the two competing mechanisms, this theoretical framework clarifies the contradictory trends observed between the present test data and previous studies.
H. Cai; Guanlin Ye; Yang Shen
International Conference on Advances and Innovations in Soft Soil Engineering (ICAISSE2026)
Field and Laboratory Testing
https://doi.org/10.53243/ICAISSE2026-205
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