What soil conditions favor the use of belled caissons? What soil conditions favor piles over caissons? What type of piles are especially well suited to repair or improvement of existing foundations and why? List and explain some cost thresholds frequently encountered in foundation design.

What soil conditions favor the use of belled caissons?

Answer:

- where the bell can be unearthed from a solid surface.

- where the supporting stratum below the bottom of the caisson is impermeable to water movement.

What soil conditions favor piles over caissons?

Answer:

- non-cosheal soils

- subterranean water or excessive depth of bearing strata make caisson unworkable

What type of piles are especially well suited to repair or improvement of existing foundations?

Answer:

Without hammering, minipiles or helical piles are placed which escapes much of the vibration and noise associated with traditional pile installation. for working close to existing buildings or for improving the exiting foundations where excessive vibration could damage exiting structures or noise may interfere with ongoing activities these piles are good options.

Why?

Their slenderness involves little or no displacement of the soil, thus minimizing the risk of disturbance to nearby foundations.

List and explain some cost thresholds frequently encountered in foundation design.

Answer:

building below the water table - site dewatering must occur, strengthening of slopes supper system must be done and waterproofing of the foundation all of which entails money

building near existing building - this requires underpinning (The process of reinforcing the base of an existing building or other structure underpins it.)

increase in column/wall load - building height determines the foundation depth