Internment Camp Pi

Internment Camp Pi is a labor camp from the Generation 1 continuity family.

In return for the troops he needed to conquer Cybertron, Megatron made a deal with the Quintessons. At least one part of that deal constituted that he had to gain access to Cybertron's core. Hence why, upon his return to and subjugation of his home planet, he established Internment Camp Pi, a labor camp where the captured Autobots are made to dig a tunnel to the planet's core. Access to the mining area goes through a tower, which is surrounded by the barracks the Autobots are locked up between shifts. Additionally to being locked up, the Autobots not at work are kept in line with inhibitor claws.

Fiction

Dreamwave Generation One comics

As a group of prisoners were brought deep into the mine to start their shift, one of them, Cliffjumper, tripped. Octane and Venom used his "unauthorized rest" as an excuse to let out their sadistic sides, but before they could punish Cliffjumper, Brawn came to his rescue. The Minibot handed them a sound thrashing until Aerospace Extermination Squadron units pacified him and took him away. Ultra Magnus witnessed all this from his occupation in he mine, distraught that there was nothing he could do. The Age of Wrath #2

Dreamwave went bankrupt before the The Age of Wrath series was completed. The details of what was supposed to happen in the unreleased issues were eventually provided by Simon Furman on his blog.
The Autobots not captured organized a mission to save their comrades, but the Quintessons notified Megatron of the life signs they had spotted heading towards the excavation site. As such, Megatron himself was awaiting the rescue party. He single-handedly took them all out. The Age of Wrath #4