In the US, load ratings are very specific in their process and how the results are defined and reported to the feds. Structural evaluations in some ways have more latitude.
That's the typical limit where the loading/design is independent. They can be closer than that; they just need to be designed considering that they interact. A proper design can account for any distance between the walls. It may require more extensive excavation for some configurations.
If that turns out to be the case, I would say the only concern is hitting concrete that flowed out into a void outside the shaft. Other than that, the existing shafts will react as a pillar of really stiff soil adjacent to your new shafts.
Multiple units to get the 10m width would be fine, but the 6m height would likely put it out of the range of sizes for a precast section, at least in most or all of the US. Casting concrete walls that high would be a significant challenge, as well.
Our preferred option for something with the...
If you can excavate behind the wall, the geofoam option can probably be made to work, but you consider reinforcing the soil mass - creating a mechanically stabilized earth (MSE) wall behind the block wall, also. We typically have the internal design done by the geogrid supplier, so we only deal...
I agree this is impractical to do as box culvert. Concrete arch, steel arch, or a bridge would be the more economically feasible options.
I see you list your job as "Student". If this is a school project, it should be posted in the Student section.
How the sag is measured does not change regardless of the percentage. It's a function of how the analysis is performed.
The percentage of sag is a design parameter chosen to meet the limitations and goals of the installation (clearances required vs. capacities of the components).
To be consistent with the typical analysis of a catenary span, I think the 6% should be measured as S3. Could use S1.
That said, in a typical analysis, the dead load is a small component of the total, with the design wind load being 80% or more. Given the very approximate nature of estimating...
Like jhnblgr, I'm not understanding the issue here. At the load position, the moment is zero, and increases linearly to the support location. The capacity of the bar with partial development can likewise be assumed to increase linearly from the face of the concrete (the increase in development...
If mitigation of the lateral support lost is required, it may be possible to increase the shear capacity of adjacent wall sections, in lieu of designing and constructing a moment frame.
For anchor bolts that I've seen where the bearing needed to be fixed and not move, but oversized holes were needed for installation, a heavy plate washer with a standard sized hole was installed over the anchor bolt and welded to the masonry plate. Not sure how or if that that would impact the...
