Preventing foundation vibration due to train movement

[enginspace]

I'm designing a small (3.5m x 5m) residential slab-on-ground for an addition to a house near an urban train line, which is subjected to vibration. The house is about 100m from the vibration source and will be supporting single storey brick veneer construction.

I'm curious to know if there is a crude way of trying to isolate (or reduce) the slab from the vibration. If the slab was a raft slab with perimeter edge beams (say 400mm deep) and 1 transverse internal beam (through the centre), could I place high-density polystrene beside the raft ribs to try and isolate the slab from the ground movements and possibly under the slab to? Or, is a post and beam floor system on isolated piers more suitable as there is less area of footing exposed to the vibration and possibly less subsequent vibration. Due to a low construction budget there is no scope for sophisticated rubber isolation pads!

Any help would be appreciated.

 

[Ron]

First of all, being 100m away from the track will likely prevent structural damage. I've monitored vibrations from train movement and the attenuation with distance is significant. Unless you are within about 10m of the track, you're not likely to receive any significant vibration. Yes, it will be perceptible and it will rattle things on the walls, but it won't cause structural damage. I'm assuming reasonable soil conditions such as sand, silty sand, clayey sand, etc.

If you want to do something positive, you could excavate an interceptor ditch between the structure and the track and fill it with gravel...this will create a discontinuous path for the vibration.

 

[a2mfk]

I agree with Ron, I have had to do quite a bit of research on vibrations, and human perception of vibration is very acute, but the frequency and amplitude of vibrations required even to cause cosmetic distress in a structure are quite high. However, keeping that in mind, this homeowner may blame you and the builder for every hairline crack they ever find in the house because "you did not do your job". This maybe can be avoided with some education to the client and I would have a signed release in regards to vibrations.