Influence of sampling disturbance and laboratory reconsolidation procedures on soils with varying plasticity

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This study presents a comprehensive numerical investigation of the effects of sampling disturbance and laboratory reconsolidation on soils with varying plasticity indices (PI), employing an advanced elasto-plastic constitutive model. Complementary laboratory triaxial and oedometer tests are performed to determine constitutive parameters and validate model reliability, with the derived parameters revealing systematic trends against soil physical properties. The first part of this paper investigates the effects of the perfect sampling approach (PSA) and ideal sampling approach (ISA) disturbance on the undrained shear behaviour of soils. The results demonstrate that sampling disturbance leads to reduced initial stiffness, loss of strain softening, increased strain at failure, and a transition from contractive to dilatant behavior. The susceptibility to sampling disturbance, governed by the loss rate of overconsolidation and collapse rate of structure, decreases with PI, with low-PI soils exhibiting greater effective stress loss and structural degradation under identical disturbance conditions. The second part evaluates the effectiveness of laboratory reconsolidation procedures. For soils with non-sensitive structure, the SHANSEP method demonstrates superior efficacy over recompression, particularly for severely disturbed low-PI soils that have undergone significant effective stress loss. A critical consolidation pressure parameter, n c , is proposed to optimize intact shear strength recovery under varying degrees of disturbance. This parameter increases with both the degree of disturbance and decreasing PI. • Propose a conceptual framework for sampling disturbance and reconsolidation effects on soils of varying plasticity. • Establish trends in constitutive parameters across plasticity via experiments and simulations. • Identify m (OCR loss rate) and a (structure collapse rate) as key factors that dominate soil susceptibility to disturbance. • Propose a critical consolidation parameter n c for optimal strength recovery. • Validate SHANSEP’s efficacy for soils with non-sensitive structure.

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