As the depth increases further, the sheet pile wall (the vertical brown members in the image) would need to stronger and stronger (heavier).

FORBES: Why Can't We Start Building The World's Deepest Building?

He will present a 10 minute rule motion to tackle the current situation where "anyone can build a wall and pile tonnes of rubble up against, without the need for it to be inspected for safety".

BBC: Meg Burgess: MP raises wall death campaign in Commons