Dirt thumper crane - GIF

[mklotz]

Do you think they can drive to the next drop point with the weight lifted from the ground?

I have no experience with heavy equipment like that but my intuition would tell me not to try moving with the weight attached.

I would work the area to be pounded in an inward spiraling path.

Drop the weight.
Back up the crane.
Tilt crane forward and attach weight weight.
Slowly bring crane with weight vertical.
Raise weight.
Repeat.

At the corners of this square spiral the crane, while free of the weight, would "turn the corner" before picking up the weight again.

This is just my conjecture about what to me is a fascinating problem. Hopefully, some of the folks who do this for a living will chime in and explain how it's really done.

Another fascinating question is why they are pounding the earth at all.

Breaking a surface layer - surely there are ground level machines better suited to doing this.
Compacting the surface - maybe but a cylindrical weight leaves patches uncompacted.
Generating vibrations to map sub-surface layers - sure, but why would they have to move the impact point around in such small increments?

[PJs]

Another fascinating question is why they are pounding the earth at all.

Breaking a surface layer - surely there are ground level machines better suited to doing this.
Compacting the surface - maybe but a cylindrical weight leaves patches uncompacted.
Generating vibrations to map sub-surface layers - sure, but why would they have to move the impact point around in such small increments?

Good questions Marv. That is a pretty big area to work like that. Perhaps it has something to do with that caliche layer Bruce.Desertrat talked about? It's also interesting that in the bottom of each hit there are pretty large hunks of something? Not a geologist but they look like rocks to me.

[Frank S]

Probably sets off seismographs 100 miles away

[bimmer1980]

A crawler crane can pick up the load and travel. Pending the size of the load and the cranes capacity would depend where the load is in relation to the center pin. Typically, the operator would keep the load low and as reasonably close to the machine without bumping the machine.

[Frank S]

I think we have been looking at this all wrong. I started thinking about the probabilities of my previous post. Then like an apple falling on my head I thought of a long forgotten tid bit in one of my civil engineering courses. they are dropping this for ultra deep soil compaction. for those times when other methods are not suitable
read the wiki on it
https://en.wikipedia.org/wiki/Dynamic_compaction

[Jon]

Good call. The phrase "dynamic compaction" pries open that rabbit hole lid perfectly. Found another way to do it, with a towed pentagon-wheeled heavy equipment attachment. At 0:50 in this video:

[Tooler2]

In the second video they mention sealing off surface water from sub soil, the very opposite of what we want on farm land. I thought it was best to have well drained road beds but I suppose if there is nowhere to drain to...
Rob

[Frank S]

In the second video they mention sealing off surface water from sub soil, the very opposite of what we want on farm land. I thought it was best to have well drained road beds but I suppose if there is nowhere to drain to...
Rob

One of the main reasons why so many roads in the USA are horribly substandard is because the compaction does not extend deep enough below the surface which allows frost heaving. In lots of areas there is ground water only a few feet below the surface this poses a huge problem even for simple single family home construction. A lot of developers have figured out they can cut corners by injecting soil stabilizers such as a mixture of caustic soda, bitumen, lime and bentonite as much as fifteen feet deep then compact the surface a couple feet deep before sanding a pad and pouring a slab. The few dollars saved makes the subdivision little more than a toxic waste dump should the subdivision ever be removed and the land reverted to its natural state.