Chemical lab escape tunnel blocked?

[unknown]

Hello,

I've encountered what I think may be a bug. When trying to leave the chemical lab after getting Substance 65, I enter the emergency tunnel when the countdown begins. However, after the 2nd right turn there is a solid wall of debris.

I can't seem to move it or get around it in any way. The walkthroughs I've seen online don't seem to indicate this difficulty.

Is this a puzzle I'm missing the solution to or is it a glitch? If a glitch, is there an easy way to resolve it?

Thanks

P.S. both Overture and Black Plague have been great; looking forward the next one.