Design Advice for Sheet Piles Supported on Steel Columns

[VVang]

I am designing a catwalk over a channel and I will have sheetpiles on bank for erosion control. The intention is to have the columns of the catwalk support and hold the sheetpiles in place. The channel is 30 ft wide and 15 ft deep, the columns are driven 65ft into firm foundation and the sheet piles are roughly 25-30 ft deep. After calculating the loads on the sheet piles and transferring that load to the columns, i am getting a massive service load. Originally he catwalk was going to be supported with 12" diam steel columns but it looks like the sheet piles might be too much. I was not able to find any examples or resources to help me. Does anyone have any tips or recommendations? Or will I need to design some massive columns to support the sheetpiles?

For reference, I am treating the sheetpile as a cantilever and after applying soil/water/surcharge loads, I am getting a moment of 114k-ft for a 15 ft cantilever. I ignored any resisting soil pressure or passive pressure because the soil is peat so I'm assuming there's no resistance.

 

[DaveAtkins]

Why are you transferring the sheet pile load to the catwalk columns? I think they should be treated separately.

 

[HTURKAK]

You did not provide alot of info . here.
I would suggest,
- Locate the 12" diam steel columns behind the sheet pile bund wall ,
- Design the sheet pile as cantilever and not supported by steel columns,
- The catwalk should have one of supports as sliding support. ( otherwise eventually the catwalk would resist some of the soil lateral load )
- Provide a sketch to get better responds.