Structural Response of Multistory RC Buildings to Excavation of a Disposal Well

Abstract

Soakaway disposal wells are used heavily in Sudan for on-site sanitation systems. These wells have a diameter of 1.5–2.0 m, a depth ranging from 10 to 35 m, and postinstalled brick walls. They often are located close to a building foundation and seldom are excavated between footings. Although engineers are aware of induced ground movements, the influence of such movements on existing structures currently is ignored both during new excavations as well as in the structural design of new buildings. This paper studied the response of RC frame structures to settlements and horizontal movements induced by well excavation using a soil–structure interaction model. The model, adopting beam theory for the structural elements and the half-space model for the ground, uses the stiffness approach to solve the excavation–soil–structure interaction. For typical RC frames in Sudan, foundation movements caused by well excavation, additional forces in the upper frame, and resulting deformations of infill walls were addressed. As a practical suggestion, for the structural design of new structures it is recommended to use strap beams connecting pads to stiffen horizontally the foundation and, thus reduce unfavorable effects of (possible) well excavations.