A framework for coupled hydro-mechanical continuous modelling of gap-graded granular soils subjected to suffusion

Abstract

In order to study the impact of internal erosion at the scale of an engineering structure, a hydro-mechanical continuous modelling approach considering suffusion is needed. It requires a relevant mechanical model for granular soils considering the $f_c$-dependency ($f_c:$ fines content) and a hydraulic model for suffusion to control the changes in the fines content. To this purpose, the mechanical models for granular soil, the unified modelling approaches for $f_c$-dependency of granular soils and the hydraulic modelling of suffusion are first reviewed. Then, a hydro-mechanical model considering both suffusion and mechanical loading is developed by combining the three components. For each component of the model, alternative choices are provided. Simulations of laboratory tests as well as an example of a dike-on-foundation problem demonstrated the reliability and applicability of this coupled numerical approach for internal erosion problems.

Keywords:

• Granular soil
• internal erosion
• critical state
• hydromechanical coupling
• fines content

Acknowledgement

The financial supports provided by the Research Grants Council (RGC) of Hong Kong Special Administrative Region Government (HKSARG) of China (Grant No.: 15209119, PolyU R5037-18F) and the National Institute for Industrial Environment and Risks of France (INERIS) are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Table 1. Summary of critical-state based models for granular soils.

Table 2. Basic constitutive equations of SIMSAND*.

Table 3. Parameters of SIMSAND.

Table 4. Values of model parameters for Foundry sand–silt mixtures.

Table 5. Summary of erosion laws for internal erosion problem.

Table 6. Model parameters for tested soil mixture.

Table 7. Model parameters of Ottawa sand-silt mixture.

Table 8. Testing programme.

Table 9. Model parameters of HK-CDG mixture.