"The bars of the pit" is a synonym for "the pillars of the earth." They're in the great gulf or "mega chasm" which is the region of Earth's interior which popular science (SciPop) calls the "liquid outer core."
The Bars of the Pit
The Great Gulf P-wave Shadow
The popular science "liquid outer core" is speculative at best, and there is no reason why it can't be open space. The P-wave shadow zone is the great gulf of which Jesus spoke in Luke 16:26.
Biblical Seismology
The testimony of Jesus Christ establishes that there's a great gulf of open space inside the Earth. It's described in the passage known as the parable of the rich man and Lazarus (Luke 16:19-31).
Sheol
Sheol refers to life beyond the grave, quite literally an underworld realm of the dead. It's also modified in a variety of ways which can be grouped to correspond to the main regions of the interior of the Earth.
Tehom was Wet. Sheol is Dry
The space in the interior of the Earth formerly occupied by the great deep is now a great gulf (chasm) of open space that Jesus spoke of in Luke 16:26. The open space is no longer referred to as tehom, it's now sheol.
Functional Orbital Mechanics
Any opposition to the popular science (SciPop) heliocentric cosmological model will be greeted with the general refrain of "it must be true because it works."
Tehom became Sheol
The region between Earth's core and mantle, referred to by Jesus as a mega chasm or great gulf, has to transition from water filled to open space due to the expansion of hell.
A Great Gulf
We're at a great advantage over the spaghetti theologians because we've deduced how the passage from Luke resolves with a physical reality. We don't regard any part of this parable as being metaphorical or allegorical.
In Hades he Looked Up
The rich man, in hell, lifts up his eyes and speaks of his torment in flame. Here's the thing: Abraham and Lazarus are also in hell, but they're not in flame. This may be confusing, but it's compatible with our model.
The Days Before Noah
The longsuffering of God waited in the days before Noah. Noah's flood saw the waters of the deep (tehom), being boiled out from under the Earth creating the open space that Jesus referred to as the great gulf (sheol).