How to destroy an underground tunnel ?

The Palestinians in Gaza have created a network of tunnels.
Many of them are up to 5 km or more in length and have multiple entrances.
Israel wants to destroy them.
It’s easy to blow the entrances up (though, it would be relatively easy to restore them later).
But what about the rest of the tunnel?
What kind of equipment or techniques would Israel use to completely destroy them ?
Presumably the tunnels are not even built in straight lines.

Please no politics
this is a plain engineering ,so to speak, question.

That depends. Does one want to preserve the infrastructure on the surface above the tunnels?

I would assume that from an Israeli point of view the total destruction would be a priority.
Whether the infrastructure above survives is secondary.

If you don’t care about what’s above, surely the easiest way is explosives all along the tunnel.

If the tunnel uses wooden shoring, you might be able to use fire.

The US tried a number of different tactics to destroy tunnels in Viet Nam. Apparently it’s a very difficult problem to solve. This article describes some of the things the Army Corps of Engineers tried: U.S. Army Corps of Engineers Headquarters > About > History > Historical Vignettes > Military Construction Combat

Pump CO[sub]2[/sub] into them.

Indefinitely?

No wooden shoring: here are pictures of the tunnels.

There’s a tool called the Rodenator used to destroy mole and gopher tunnels. It uses propane and oxygen pumped into the burrow in an explosive mixture which is then ignited destroying the tunnel. Might work on a larger scale.

In The Great Escape, Paul Brickhill wrote that the Germans had a hard time getting rid of the escape tunnels the POWs dug under Stalag Luft III. They were so well-shored* that they wouldn’r easily collapse – they had ben used to using a high-pressure water hose to wash sand and soil into the shallow tunnels at other camps, but the well-shorted 30 foot deep tunnels the escapees had dug and shored up stood up to that.

They tried dynamiting them, but this caused the chimney in one hut to collapse, and wasn’t entirely satisfactory.

The best solution they came up with was to fill the tunnels with latrine waste from the “honey wagons”. No one wanted to try and dig through that. And if they tried, it’d be a dead giveaway.

I thought those were more to destroy the tunneling equipment.

Forgot the footnote
*They shored up the tunnels with bedboards (as shown in the movie), with parts they scrounged from the extra construction on the huts, and pieces pilfered. The sand thirty feet down under the camp was loose, cumbly, and very yellow. It had little cohesion, and collapsed on them as they dug (also as shown in the movie). So they shored it up. They tried to be as sparing as possible, to stretch their supply of wood (they levied the bedboards early on and hid them away, so the German “ferrets” wouldn’t notice that they were constantly disappearing and catch on to the tunnel being dug), but the sand was so loose that they had to have almost complete shoring the length of the tunnel. It wasn’t a luxury, but a necessity.

Just pump them full of concrete; that’s what they do to tunnels coming from Mexico.

This has already been done in Gaza, a year ago.
Not by the Israeli army, but by the
Egyptians

But those were much shorter tunnels, mostly open and visible, and used to smuggle goods under the border fence with Egypt.

What? Come on, you think boards in a small tunnel stuck right up against the dirt will ever burn through significantly? No surface area for the fire to burn on, let alone let oxygen in. And here’s an added confounder, burnt/carbonated wood is actually stronger than the original wood (well, burnt to a certain degree only, and of course it loses its tensile strength. Plus, this is just something my Dad told me (we’re builders) )

From what I understand, that doesn’t destroy the tunnels, just the rodents/critters. Why would it destroy the tunnel? There is a “blast” but it isn’t significant enough to destroy tunnels in solid dirt, it’s only some light flammable gas, hardly a bomb set up or dynamite.

Like most things underground, just write a cover story for Time declaring it the “next big thing,” and it will die out pretty soon on its own.

there are bunker buster bombs

Half ass plan …

… now completed.

Thx chacoguy.

Is it? You could pump sulfur hexafluoride or similar heavier-than-air gases, and it would push out the air, making the tunnel impassible (you’d asphyxiate). And indeed with something as heavy as sulfur hexafluoride, that set-up would be pretty stable (winds would push out some of the gas at the ends, whenever there would be said winds, but this could be replaced by pumping more gas later. And indeed, I do believe the gas would be cheaper than concrete
It’s an interesting proposal