Foundation, construction and performance for a 34-storey building in St Louis

A high-rise building consisting of a tower and adjoining low structure was constructed in 1968. The tower was founded on piers socketed into bed-rock, and the low structure on an overcompensated mat supported on medium silty clay. The significant aspects of the construction of drilled piers for the tower and the braced excavation for the low structure are described. Field measurements were made in the braced excavation; they consisted of measurements of loads in the struts during and after prestressing, lateral and vertical movements of adjacent streets and buildings, and heave of the bottom of the excavation. Strut loads agreed with Peck's apparent earth pressure envelope, except where the struts were prestressed to a higher load during installation. After construction, some measurements were continued, particularly of the mat foundation settlement and the strains and stresses in one rock-socketed pier supporting the tower. Difficulties with loss of ground during construction of the drilled piers are des...