# Research on composite foundation rheology using the combined rheological element model

## TL;DR

This paper proposes a new model to study the rheology of deep soft soil composite dam foundations, improving accuracy in predicting stress, deformation, and seepage.

## Contribution

A new combined rheological element model is introduced for simulating deep soft soil composite dam foundations.

## Key findings

- The model accurately reflects stress, deformation, and seepage with an error within 5%.
- Consolidation rheology and fluid-solid coupling significantly affect dam component strength during impoundment.
- Settlement changes in the composite foundation are influenced by rheology over decades after initial consolidation.

## Abstract

The safety and stability of the dam are affected by the rheology created by the deep soft soil layer following composite foundation reinforcement. Based on the classical combined element modeling, a new combined rheological element model is proposed in this paper. The consolidated rheological and fluid-solid coupling model is established by COMSOL to simulate the deep soft soil composite dam foundation. The results demonstrate that the model can better respond to the actual situation of stress, deformation, and seepage in each stage of the dam, and the error is within 5%. The strength and stiffness of every component of the dam are most affected by the consolidation rheology and fluid-solid coupling of the dam foundation during the impoundment phase, and the growth rate of each index gradually slows down with the extension of the running time. The rheology of the deep soft soil composite foundation is continuous. During the normal operation of the reservoir, the consolidation and settlement of the composite foundation are basically completed in 4–5 years, and the subsequent settlement changes are affected by the rheology for decades. The research results theoretically support the construction of safe and reliable system of deep soft soil composite foundation including clay core rockfill dam.