Step 1: Understand the Dam Stability Concept.
The stability of a dam is influenced by the forces acting on it, particularly the horizontal thrust (T) and the weight of the dam (W). For stability against rotation, it is crucial that the resultant of these forces passes through the base of the dam, ensuring no overturning moments.
Step 2: Identify the Key Conditions.
- The horizontal thrust (T) and the weight (W) must be balanced and pass through the base to avoid instability or tipping.
- L is the base length, H is the height of the dam, and CG is the center of gravity.
Step 3: Conclusion.
The condition for the most stable state of the dam is when the resultant of the forces T and W passes through the base of the dam, preventing tipping and ensuring stability.
Final Answer:
\[
\boxed{\text{Resultant force of T and W passes through the base of the dam}}
\]