Interesting. Thanks for sharing.
I presume the red jack was used to load test each anchor individually and the reaction force is provided from the outer collar that has a bracket secured to the house foundation, using the dead load of the house foundation as the reaction force. Once the jack is pushing on the outer collar (as shown in the picture), it would seem it’s akin to lifting yourself up by your boot straps (e.g. no appreciable force is being applied to the anchor once the anchor has deflected that far).
This load test is similar to the name sake’s Ram Jack system where a metal pipe is installed by simply jacking it into the ground using the dead load of the house that a tributary area that lightly reinforced concrete (slab or stem wall) foundation can be relied up.
My criticism of these systems is the the factor of safety is very close to 1.00 since the spacing of the anchors is about what the tributary span/area of a typical lightly reinforced residential structure foundation is, say 6 to 10 feet. Typically a FS of 2.5 to 3.0 is desirable relative to the geotechnical capacity of the substrate.
I notice the jack only has one hydraulic line (no return line like a typical ram used for a load testing would have), but then I’m used to 250,000 to 2,500,000 pound load tests. Obviously one line will suffice for a 10-20 ton bottle jack.
If anyone’s interested, I found this International Code Council Evaluation Service Report on the hydraulically driven RamJack system (not the helical anchor system). Interesting how it says the spacing of the anchors is essentially controlled be either lifting (4.2.1, Item 5) or damaging the foundation. Although 4.1.1 states, in the 9th bullet that the spacing of the anchors must be addressed, if different than stated in 5.14, 5.14 states the anchor spacing (interaction) is outside the scope of the report.
ICC-ES Evaluation Report ESR-4331 02/2022