How Does a Digital Platform for Triaxial Soil Tests Work?

Imagine studying soil behavior without setting up expensive labs. Researchers have built a digital platform, based on MATLAB, that simulates triaxial tests on saturated clays. The breakthrough lies in merging two advanced models: the Anisotropic Structured Clay Model (ASCM) and the Anisotropic Creep Model (ANICREEP). These models capture how soil reacts to different loads, accounting for anisotropy and slow-time deformations.

The platform offers four typical testing conditions, letting students vary pressure, drainage, and loading speed. With a few clicks, they obtain stress‑strain curves and track key variables such as pore pressure and density. The main benefit is instant visual feedback, bypassing lengthy mathematical derivations.

For “Soil Mechanics” courses it serves as an immediate teaching aid, while the master’s program “Numerical Computation in Geotechnical Engineering” uses it to dive deep into constitutive model theory. Moreover, the solution is cheap, sustainable, and easily extensible: anyone can add new models or experimental scenarios. Thus, digitalization becomes a true engine of innovation, creating a shared resource for universities and research centers.

The ASCM model relies on an anisotropic elastoplastic formulation, where the yield surface is described by an ellipsoidal function dependent on loading direction. This captures the effect of layered clay deposition, generating stiffness differences parallel and perpendicular to the deposition plane. ANICREEP introduces a visco‑elastic creep term that depends on loading time and pore pressure, modeled through a modified power law. The two models are integrated via an incremental integration algorithm based on a modified Newton‑Raphson method, ensuring convergence even under strong non‑linearities. The platform exploits MATLAB's 3D visualization to display the yield surface and state trajectories in stress‑strain‑time space, aiding interpretation of phenomena such as anisotropic softening and hardening. Moreover, the code is organized in OO modules, allowing extension with additional constitutive models (e.g., Cam‑Clay, Hardening Soil) and coupling to FEM packages for more complex analyses. Validation was performed by comparing simulated results with experimental triaxial tests on Kaolinite clays, showing errors below 5% for peak pressure and final strain.