To counter act the tilts in the well during sinking operations, which of the following measures can be used?

The most economical shape, of a well for the construction of large pier is _____

A sharp vertical edge for the well is provided at _____

The well curb is designed for which of the following purpose?

For loose sand, the value of skin friction is between ____

The bottom plug is designed in _____ shape.

The working chamber of pneumatic caissons are kept airtight because ____

A disadvantage in using circular shape of well foundation is _______