I would like to add that the soil pressure does not only effectively act on the nodes and transfer that load to the surrounding nodes, but it also acts on the flat surfaces of the covering membrane or sheet that form the facets, and put these facets into tension. Ie your covering bulges inwards at every facet. For this reason I would recommend a higher frequency dome for underground than might be chosen for above ground situations. You want to keep your facets as small as possible. In addition to this, I recommend that the first layers of Earth are thinly applied and dry mixed with 5 % Portland cement so that these first layers of earth are structurally self supporting and contribute to the strength and thickness of the dome, before adding further earth.
It's is nice to see that you guys are still there. I have emailed and commented with no response. I bought plans for a dome but they were not sent to me. Can I please have the plans or a refund?
Sorry to hear you didn't get your plans, most common problem is email related, had a few problems lately. Can you email me at "Paul(at) geo-dome(dot)net" let me know which plans and I'll get them out straight away
...Galvanic protection would be required as protection from any underground currents (causing the structure erosion), the evalution of the hydrostatic thrust of the groundwater on the sides of the structure (variable over time, can cause fatigue stresses in the joints), the evaluation of any differential subsidence in the foundation layer, and many other factors must be considered... It's not simple.
You're right. It's not simple, but neither complicated. With the right tools and skills, this can be worked out in less than a day to arrive at a structural sound construction. A matter of using the proper materials and knowing what their properties are.
If an impervious layer is laid over the structure and extending well beyond the structure, it's possible to keep the soil completely dry year-round. Just need to build above the water-table, too. Dry soil weighs less and doesn't transfer heat as fast. Look up Passive Annual Heat Storage (PAHS) for more information.
A quick calc: 9 meter diameter dome, half sphere, has a surface area of approximately 128 m2. Clay has a weight of 1,826 kg/m3 (wet excavated clay). So 1 meter coverage with clay amounts to 234 tonnes. That weight is NOT pressing on the dome perpendicular to the surface of the dome. For example, the first 1 meter of clay around the dome excerts very little force on the dome. It presses vertically down on the foundation or soil next to the dome. This first meter of clay has itself a bearing capacity of around 5,100 kg/m2. Assuming the soil you build on has a higher bearing capacity, this means that the first layer of 1 meter clay serves as foundation for the next 1 meter, and so on. In short, the dome will not receive a pressure of 234 tonnes, but much less, due to the extra bearing capacity of the clay. My advice is to NOT build an underground geodesic dome unless you have done the necessary FEA or hire an engineer to do that for you. We did all the FEA and more on our domes to make sure "terrible accidents" won't happen. Using the right materials and proper engineering is paramount (in any construction).
Paul! You're speaking my language! I've got great plans to build this exact thing. If you'd like to collaborate on a couple videos please let me know so I can give you credit. Thanks, Jeff
Surely, the most efficient shape for load bearing is a circle…or part of, so the loads applied are dissipated in all directions and either strengthens the structure, or in part of a circle, I.e. an arch and pillar’s is capable of transferring the load to the ground… In a dome of this design there are numerous ‘flat points’ in the structure where the load, or a large part of it, will not be transferred, but will bear directly on that flat surface…therefore the structural strength of the material employed in those ‘flat points’ where a load is applied, must be capable of withstanding that load, plus a safety margin… if not it will fail, and failure of part of the structure will lead to unbalanced loads being applied to the remaining structure, leading to supplemental failure and collapse…!!!
The best bet would be to use the dome structure as a leave in place concrete form. Cover it in reinforced concrete. You can cover the wood with a EPDM roofing material for water proofing. Set the rebar then spray your concrete on. Let cure, then water proof and insulate to protect the water proofing from the dirt. We did a containment for a mine site with a spray on bed liner as a water barrier. Same as a spray on insulation application for a house.
I'm about to tackle the underground dome. Some of the engineering specs are: must not use any conductive materials; must be able to use reclaimed or scrap materials, must survive earthquakes, and be able to stop radioactive fallout.
Anything with flat faces should never be used underground. A spherical section is the only "safe" shape. Having a flat top, like you have, is a recipe for death.
I have a question. If you put a support in the center running from the roof to the floor would that increase or decrease the maximum weight that could be placed on top of the dome?
the water problem seems to me the best solution is to put drainage under the structure before you start and build this above the nearby ground level on at least one side so you can drain
Paul, your explanation about how the dome could fail shows why such a dome (loaded with soil overhead) should use the trussed dome design. By trussing the dome, entire modes of failure go away. The one thing I've noticed is that the wanger flange is probably not well suited for a trussed dome because a ring of the flanges that would support 10 strut ends would not have as much rigidity as if all struts came to a point.
Paul, I keep emailing you about your GD15 Mini Eden plan with no response from you. There are things that are missing from the plan. Could you please clarify those?
So, I have a greenhouse outside and was wondering if I could hook my vent pipe in the ceiling up to a pipe and run it to my greenhouse. My home is like pictured almost, but has passive solar heating and is 65-75 year round. Will this work?
As a suggestion.... Sump connected to external french drain and sump pump(s) with battery backup. Put your dirt covering in layers with geotextile every 50 to 100mm to mitigate soil movement and wick the water at a steady rate.
You're assuming the only possible failure points are at the vertices, but the flat triangular faces are likely weaker and can deform or crush inward catastrophically depending on the material. The larger the triangle the more likely it is to fail.
