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Diaphragm Wall with 4m Embedment into Medium/Hard Rock

Diaphragm Wall with 4m Embedment into Medium/Hard Rock

(OP)
Hi, guys. I'm looking for an information on the on-going (still under construction) project with a diaphragm wall embedded into medium/hard rock more than 4m.
It does not matter where the project site is globally.

The design of my project requires the diaphragm wall to be inserted into med/hard rock more than 4m with a rock pin or H-pile down below.
The profile is; Top 15m is the sandy silt with gravel and below 15m is med/hard rock of 55~100MPa UCS values.
Total excavation depth is 30m, which gives average 19m D-wall and 11m toe pin below.

However, the local sub contractors do not have a proper equipment or experience for this 'deep' rock embedment scheme.
This is due to the fact that normal local geology here has 'sound' weathered rock above the base rock and usually less than 1m embedment into the base rock is enough for the D-wall stability.

This situation requires me to find a project of the same or similar condition.
If possible, I'm considering to visit the site and the contractors to see the actual construction with my subcontractors.

Thanks.

Paul

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

I would get in touch with a company like Bauer, Trevi or Soilmec who have the capability to do this type of work.

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

(OP)
Thanks, Retrograde. Will try that, too.

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

Just to be clear...based on the UCS values provided you are dealing with hard to very hard rock at the base of the structure.

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

Clearly it can only be done easily with a hydromill (which can accommodate up to 130 MPa UCS). Therefore you must look for companies who operate this type of Equipment (Nicholson, Bauer, Trevi, etc)
Alternatively, you could think of predrilling and use mechanical cable grab and chisel if you can't dspose of a hydromill rig but it will take more time.

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

(OP)
Yes, Mad Mike and BigHarvey.

I have medium to hard rock at the base and need to mobilize the special rig for it.
Previous trial of using pre-drilling and chisel did not come out with the satisfactory results.
That was why I was looking for the similar cases as I can't find any in the country.

As recommended, now I'm discussing with one of the mentioned suppliers.

Thanks, guys. 2thumbsup

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

Try to find a smart consultant to design a 0.5-1.0m embedment into concrete like rock, not 4m!

RE: Diaphragm Wall with 4m Embedment into Medium/Hard Rock

Grabs cannot penetrate hard rock. What I had done in previous projects when we have both grabs and hydromills, we would start with grab in soft soil with smaller size, than second machine comes and goes into the hard rock.

But I would like to see toe pin design. We do not do that here. So you cut diaphragm wall before maximum depth of excavation? Do you have a simple sketch?

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