Thanks for your Answering

Your question

How does the self-healing property of clay Earth-Rockfill dam ?

is not clear, do you mean how to evaluate self-healing property ?

Hello Mohammadmahdi Mohammadyar

I will assume that your question means "How is a clay core rock fill dam self healing?"

A properly designed rockfill dam with clay core should have graded filter zones of earth both up and downstream of the clay core.

The purpose of the the clay core is to limit the seepage loss through the dam.

This is achieved by the downstream filter preventing the fine particles in the clay from being washed into the downstream shell of the dam and also by the upstream filter preventing the hydraulic cracking of the core by high seepage velocity of water moving into the core.

The system of filter and clay core is self healing because should a crack apply in the core say because of differential settlement it is rapidly closed (healed) by the migration of earth into the core to seal the crack and by the downstream filter preventing further loss of material.