The process you are describing is called freeze-thaw weathering or frost shattering. It is a mechanical weathering process that occurs in environments with freezing and thawing cycles. Here's how it works:
Water enters cracks and crevices in the bedrock.
When the temperature drops below freezing, the water freezes and expands, exerting pressure on the surrounding rock.
The repeated freezing and thawing cycles cause the cracks to widen and the rock to fracture into smaller pieces.
As the glacier moves over the fragmented bedrock, the loose pieces of rock can become frozen into the base of the moving glacier.
This process contributes to the erosion and transportation of rock debris by the glacier.
Freeze-thaw weathering is a significant factor in shaping landscapes in cold and alpine regions, where the expansion and contraction of water in rock fractures contribute to the breakdown of bedrock.