Question

Brief report on Shaft friction of non-displacement piles in sand.

Answer 1

Generally the shaft friction on non -displacement piles depends on mainy these factors like as-

1)The value of shaft friction

2)pile surface roughness ,this varies from (2-5)*D50 for a smooth pile and (10-15)*D50 in case of rough pile,D50 signifies mean particle size of sand particles

When the load is imposed on pile,the pile is subjected to large plastic straining,the soil can behave as a dilative or contractive which depends on its state after the installation of pile

When we see aspect of roughness normalized roughness is considered which is defined as Rn =Rt/D50(where Rn is normalized roughness,Rt is maximum pile surface roughness measured end to

end )

when Rn is less than 0.02 the interface surface is smooth, then no dilatancy occurs

when Rn is more than 0.1 the interface surface is rough, then dilatancy occurs

The failure occurs due to two reasons

1)sliding between soil and pile surface

2)failure inside soil surrounding the pile