Hey guys, new to the site and was curious if anyone has done any settlement monitoring. The problem we are having on site is that 4 foundations (approximately 18x18x3) have been settling over the past year. We noticed it when our benchmarks started not checking between themselves and have been monitoring them ever since. Over roughly 8 months they have settled about 0.12'. Injection grouting is currently taking place to try to get them to stabilize however within two days of grouting they sank another .03'. Has anyone experienced this and if so did the injection grouting help or hurt?
If the soil is unstable the heavier the block of concrete the faster it sinks. As far as your question goes I'll leave it to the geotechnical engineers. I have enough trouble with the surveying.
Not all construction sites are equal.
Compacting the fill and exposed surfaces is great, will not compensate for subsurface soils that have not been tested.
Many older construction sites begin to fail during expansion because the materials have been shuffled around for decades creating soft spots that go unchecked and forgotten.
I worked restoration for a bit, including mud-jacking. It's hard enough to get things right with proper testing and evaluation. It won't happen on a thread.
Are you interested in monitoring or stopping the settlement.
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We had a geotech firm come on. They bored hole at the corner Tha t was dinkining and shoved a boxcar full of wooden posts down the holes. The soil type was bentonite. The building was designed with extra wide footings, but it still settled after about 10 years. Helical piers we're suggested, but it was decided that they were too expensive and not a gauranteed solution.
mat30, post: 452497, member: 13142 wrote: Hey guys, new to the site and was curious if anyone has done any settlement monitoring. The problem we are having on site is that 4 foundations (approximately 18x18x3) have been settling over the past year. We noticed it when our benchmarks started not checking between themselves and have been monitoring them ever since. Over roughly 8 months they have settled about 0.12'. Injection grouting is currently taking place to try to get them to stabilize however within two days of grouting they sank another .03'. Has anyone experienced this and if so did the injection grouting help or hurt?
Yes, I have done monitoring on projects like this. The client I work with does jet grout, ISS columns and slurry walls. In the case of Jet Grout the remedial area always changes elevation. You need original BM's to be way out side this area. In most cases the elevation go up, when jet grouting. As the volume of concrete is pumped into the ground with air, it creates displacement. But in your case there may be underground void or cavern. We have seen surrounding house foundations shift, sheet rock cracks, shifted door sills prevent the doors from closing. I have seen sites elevate by 5 inches.