Drilled Shafts - Cleanout of shaft before start of rock socket

[JMackNH]

I am reviewing an installation plan for a number of drilled shafts. These are dry-cased, end-bearing shafts anchored in bedrock. The procedure states that once the bedrock is reached, the shaft needs to be cleaned out before the rock socket is drilled. Is this done just to verify top of rock or are there other reasons for it?

 

[MotorCity]

If you are relying on the bond between the concrete and bedrock, it should be cleaned to maintain the integrity of the bond. If the shaft is mechanically anchored to the bedrock w/ dowels (i.e. not relying on the bond)than there is no reason to clean it. Understanding of course that we are talking about a minimum amount of soil/debris and not a heap of debris sitting at the bottom of the shaft.

 

[JMackNH]

Judging from the designs, it is mechanically anchored. Good to know about the cleanliness. I always try to put together a 'which battles to pick' assessment before these types of projects. Thanks!