Contiguous Pile Facing wall design

[phuduhudu]

We are proposing using contiguous 300mm dia pile walls for a domestic basement in clay where the ground water level is below the basement level generally. However, the basement obviously needs to be designed for a higher water level. I assume that in the permanent case the piles could be designed for the earth pressure and a concrete facing wall would distribute the water pressure to the piles. We would rake out loose soil between the piles and put a mesh in the facing wall leaving min 40mm of concrete to the face of the piles with the concrete facing wall then varying between this min 40mm and max of 40mm plus 150mm pile radius between piles. I am assuming that structurally the facing wall would not be working hard as it only needs to span the 100mm or so gap between piles or do I need to design the facing wall to span the depth of the basement independently of the contiguous piles? We are not expecting it to be watertight so some dampness would be acceptable as we would have a drained cavity in front of this wall.

 

[Retrograde]

Generally I do not like to use less than 75mm thickness for a concrete facing wall (shotcrete). Thinner than that and you can get problems with cracking. Also, there is little cover to the mesh with only 40mm thickness.