I think you can use precast concrete such as a septic tank or rings. My
measurements made a LONG time ago in NM indicate that a mere 18 inches
depth leads to less than one degree (God's units as revealed by the
French) over the period of a year. Bring wiring in via a trench at the
surface level of the top of the vault. Ideally, the cover should be
insulation to near surface, then soil. That's the one sticky point
because as you will know, thermal vortices will be set up in the vault
air. very small slow fans may control?  The flow can be modeled,  I
think.
Don

On 2021-09-08 19:54, Tom Van Baak wrote:

The whole world is a straight man.

Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304

On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote:

Tom,

How long do you expect your proposed voult to go undisturbed?
I have several pendulum clocks.  They are disturbed every couple of months
by earth quakes.  By disturbed, I mean pendulum banging against the case walls....
Any ground motion that can be felt will upset the clocks.  Often the clocks will
signal an earth quake that is not felt.

Good luck.

Bill Beam
NL7F

Temperature stability will vary with climate. Here in upstate NY, you’ll need to get to >50” of depth to start to get any real year round thermal stability. But a local civil engineer should know that number well. We also have to worry about water intrusion, even with concrete, depending on depth.

Interesting subject.

Tom Van Baak writes:

I researched this extensively before we built a house 5 years ago.

Look at the plot on page 37 in this paper:

https://www.researchgate.net/publication/279526204_Temperatur_og_temperaturgradienter_ved_og_under_jordoverfladen_i_relation_til_lithologi

It shows that in Denmark the yearly temperature variations in
penetrates to a depth of 15 meters, and that even at 10 meters
depth, you can expect the swing to be several Kelvin in any year.

I did find handwaving which said tree-cover reduced the swing by
"a lot" but no measurements to substantiate it.

In the end I concluded that I could do better in the comfort of my lab.

You should try to find similar data for your local climate and
geology, before you pour too much money into a hole in the ground.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

On 09/09/2021 03:36, Bill Beam wrote:

Bill,

It sounds as if you live in an area where monitoring of earthquakes would be of
interest!  If you haven't got something already, you might like to look at the
Raspberry Shake:

https://raspberryshake.org/

The devices are not at the professional seismograph level.  They operate a
world-wide network.

73,
David GM8ARV

SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv

Hi

You could do some research on the climate in various parts of the world.
Pick the ideal location and move there :) :) You also could optimize the
location for various tidal forces ….

How deep can you go on your property before you run into something
massive? Around here, I can go down between a foot and maybe two
feet. At that point it’s time for dynamite. You do not ask “how much to
put in a swimming pool?” in this neighborhood.  Part of this is the geology,
part is how the builder graded things to  put in the subdivision.

While that sounds ideal, the shale is tilted due to some thing running into
something else a while ago. The net result is ground water running here
and there to some fairly significant depths. As the seasons change that
ground water and its somewhat random route changes isn’t ideal for
temperature stability.

Yes, it’s all about some very local aspects of your geology.  With some
care, I could move a few miles in one direction or another and be in a very
different situation. (again thanks to just how this ran into that ….).

Since temperature stability is only part of the design and mechanical
stability is the other. This location might work ok for half of the design
goals …. Granite likely would do better than fractured shale though ...

Bob

Seismic vaults are built similar to your requirements.  I suggest looking
up the Earthscope program - there should be info out on the web as to how
their vaults were designed, but in a nutshell, dig a hole, put some gravel
in the bottom, place a large culvert on end in the hole, pour a few inches
of concrete in the culvert, put instrumentation in a pedestal inside, run
power and comms, put a bilge pump and outflow pipe in it on the floor
(below pedastal), and put a cap on the whole thing.  Those were then
re-buried, but that prevents easy access (although it probably improves
temperature stability). A septic tank would be larger, but more effort, and
may expose more surface area to the sun (temp variation).

I've been in various seismic vaults and they can vary from very extravagant
to downright crude.

On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq kb8tq@n1k.org wrote:

On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ:

How deep?

Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment,
facilities, and operations of Bureau International de l'Heure at
Observatoire de Paris.

The highest precision pendulum clocks, the ones which had mechanisms
to correct for temperature and pressure (the "garde-temps") were kept
27 m below ground in caves and galleries which were part of the
Paris catacombs.

Various issues of Bulletin Horaire report discontinuities in the
operation of those clocks due to distant earthquakes.

--
Steve Allen                    sla@ucolick.org              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street              Voice: +1 831 459 3046        Lng -122.06015
Santa Cruz, CA 95064          https://www.ucolick.org/~sla/  Hgt +250 m

Hmm, this list isn't called time-science, time-research, time-hardware,
or time-trivia. It's called time-nuts.  This is probably one of the most
on topic (and fun) posts I've seen on this list. :)

Regards,

John

On 9/8/2021 7:54 PM, Tom Van Baak wrote:

On 9/8/21 6:54 PM, Tom Van Baak wrote:

A few years back, we were looking at building a "test rubble pile" for
search and rescue applications (actually for testing equipment that
would be used for this).

For the depths you're talking about (few meters) the easiest approach is
to get someone with a backhoe to dig a pit, then use the backhoe to
carry the precast vault, drop it in, and you're done.  If you were going
more than "backhoe depth" you're looking at something like an auger, and
they can drill any diameter (up to about 4 feet) and any depth, as long
as they can get the truck into position (same as the backhoe).

I went around looking at the precast concrete vendors - they're
available in any size you want. You can also just sink a drain pipe of
any size vertically, and fill the bottom with concrete. The vaults often
come with "knockouts" - places where you can bring conduit in by
knocking out the plug of concrete (it's cast with a thin ring, so you
hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault
seal is done with a variety of goops. Some of the ones I've seen look
like tar (the same stuff used to fix roads, roofs, shower pans), others
use some sort of foam.

The prices for this stuff are fairly standardized - your local utility
or roads department probably has a "standard bid list" for most of the
more common items that they use for doing estimates. Caltrans certainly
does (a 48" precast concrete manhole is about $1500). So that gives you
a ballpark when you start calling vendors.  The big driver for most
people in a "residential" environment would be access.  It's one thing
to have a double flatbed show up with a bunch of concrete pipe on it at
a business, totally another on a winding residential street.  We had
stuff delivered on a flatbed truck with a small crane - but they could
just pull up to the site, sling the vault, and lower it to the ground,
and then the backhoe guy moved it.   Going up a driveway, around the
corner, avoiding the fence, etc. would be different. Or, A really big
crane - I've seen that done - 80 or 100 foot boom in the street - they
pick the load up, lift it up and over the house and place it in the back
yard.

https://precastconcretesales.com/manholes/

https://www.columbiaprecastproducts.com/products/precast-manholes/

https://www.gardenstateprecast.com/pdf/2019-price-list.pdf

Google "precast concrete manhole" and select accordingly.

You're looking at the "more than $1000 probably less than $10k" range,
all done in a day, plus a day of prep and a day of cleanup.

Backhoes (in SoCal) are going for $300-500/day plus the operator
($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as
a rookie, but digging a hole is pretty easy to learn on your own.  And I
just looked it up, the smaller skid-steer bobcat type could probably dig
a 2 meter deep hole, and you're less likely to do major damage like you
can with a full sized unit.

Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day ,
$1005/week

https://www.compactpowerrents.com/rental-equipment/mini-excavator/25-3-ton-mini-excavator/
You might find someone who's usually doing stuff like pools and spas,
and will dig your hole for you. In any case, probably not more than $1000

One other source for design is "storm shelters" - FEMA has published
pre-engineered designs for a variety of inground shelters (often,
installed below a garage)

One final thing - even if it's waterproofed, it will collect water
either by condensation or seepage. You might need to make your clock
vault have some sort of dehumidifier and/or sump pump.

The other alternative is to "build a basement" - dig the hole by hand,
pour a slab, and either pour walls or stack blocks and pour into the
cavities.  1x1x2 meters is sort of doable.. figure standard 8x16"
blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft. 
That's big enough to stand in, but there is a significant cave-in
hazard, If you're down 2 meters, and the side collapses on you, you'll
probably die before they can dig you out. Or, your soil is sturdy
enough, you manage the risk.
I don't think you could dig 2 meters down with one of those small bobcat
backhoes or excavators, you'd have to dig a ramp, stack your blocks,
then backfill.

Sounds like we need a volunteer time-nut with motion picture camera
capability to document this event.
--- Graham

On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim jim@luxfamily.com wrote:

I've seen discussion of making a seismic vault (though not sure if
they used that name, making it harder to find in the haystack of
posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if
this is helpful:
https://www.seismicnet.com/maillist.html

For possible immunity from earthquakes, LIGO uses some quite complex
control and feedback systems to hang its mirrors so that mild
earthquakes and local noise won't affect them. From what I've seen
over the years a lot of this info has been published, but I imagine it
would be quite expensive to reproduce. Maybe some sort of Ligo Lite
system would be feasible.

On Thu, Sep 9, 2021 at 10:13 AM Brent brent.evers@gmail.com wrote:

Tom
When I added a machine shop to my home I devoted a part of it to set up
and run a number of precision clocks which at the time consisted of a
Fedchenko, two Shortt clocks and a tank Riefler. Of course the room was
above ground and all of the problems regarding temperature and vibration
had to be considered. The concrete floor of the room was particularly
deep and I had arranged to have two large square holes made (when the
floor was poured) in the floor into which I mounted two 3000 pound
square freestanding concrete blocks that were floor height. The blocks
were mounted on vibration isolators (used to mitigate the effects of
earthquakes in California buildiings) which I had made. Although it
wasn't perfect it did help with the local road noise and random
vibrations. What I hadn’t counted on was the change of seasons and heavy
rain. When I set up the clocks (Fedchenko on one of the isolation blocks
and an Englsh Shortt on the other) I mounted a very sensitive tiltmeter
on the floor of the room and found that when we had a long duration
rainfall in the summer, the entire floor tilted slightly. It did the
same when the seasons changed from Winter to Summer. Keeping a steady
temperature also proved to be difficult. The tiltmeter was of the type
used on bridges to check for beam flexing and was made by Sperry. My
house was built in the 50's and I believe a good deal of fill was used
to level the site. This most likely caused the problem. Neverthess I had
quite good results with the clocks.

Bill S
www.precisionclocks.com

On 9/8/2021 9:54 PM, Tom Van Baak wrote:

Hi

So you build the buried clock vault out in the yard. My guess is that
simply in order to get in and out of it, the size will grow to something
like 2 x 2 x 2 m. ( how do you, a ladder, and a bunch of clocks get into
a 1x1M square without crashing into stuff all the time? ). I’d put a raised
floor in it simply so the slope to the drain doesn’t drive you crazy. Some
space at the top for lighting might be nice. Now it’s up to maybe 2 x 2 x 3 m.

None of this helps the budget any, but it does increase the mass. It also
lets you space things out a bit more. Injection locking is probably not
what you want between the clocks.

If the top / roof is simply sitting there at ground level, the sun comes along
and does this or that to it on a daily basis. Either you sink it another meter
and put a dirt layer over the top or you build a hill over it. You might put
in a small building over the top.

No matter what’s on top, you still need to get in and out of your vault.
A ladder might work. I know that bringing the sort of stuff you are talking
about down a ladder would not be anything I would even remotely want
to try. Stairs and multiple doors would work, but you just > doubled the
size of the hole. It’s not quite clear how you deal with the “thermal leak”
that the stairs create. The door to the stairs also uses up valuable wall
space. Even a trap door to get to a ladder would require a bit of thought.

Unless you have a really ideal area for drainage, there will be some sort
of sump pump down at the bottom of the beast somewhere. Yes, I have
one here, despite the issues the neighbors have, mine has never turned
on. Still glad it’s there. You don’t know if you need it until a couple of
years have gone by.

One approach to this I actually have seen done is to go to a basement
below the basement. The objective in that house was a sizable wine
cellar. The claim made was that the cost of putting it in (on that property)
paid back in cooling costs fairly quickly. I never asked to see the math
that backed up that claim …. The wine inventory was impressive ….
One might note that the house was on a pretty steep hill.

The family may or may not be up for dynamite being used just outside
the kitchen window. This vault sounds like a “not going to spend a lot
of time in there” kind of thing. How about a vault under that summer
cabin in the woods you didn’t know you needed until about 3 seconds
ago?

Bob