In this method, a circular hole is excavated up on the depth at which the soil will stand unsupported (about 0.5m for tender clay and 2m for rigid clay). Vertical boards called laggings, are then set in placement within the excavated face and are held tightly towards the soil by https://availableonspotify99988.wizzardsblog.com/30615516/foundation-pile-testing-bd-an-overview