Dynamic Study of Existing Structure Influenced by Adjacent Deep Excavation

Abstract

Rapid growth and expansion in metropolitan cities necessitate the construction of buildings very close to existing structures. Whenever there is an excavation made adjacent to structure, the soil below the footings gets disturbed due to the lateral escape/displacement of soil and subsidence of soil, and hence a decrease in the bearing capacity of the soil around it. It is therefore required to assess the impact of construction on the nearby existing structures. The main aim of the study is to identify the variation in the dynamic properties of an existing frame structure adjacent to deep excavation and to find the response of the structure under seismic excitation. The analysis of structure without adjacent excavation is carried out and is treated as reference for six other cases considered. For three cases, the distance of excavation from existing frame structure is kept constant (as 0.5 m) and the depth of excavation is varied (1.5, 3, and 4.5 m). In other three cases, the depth of excavation is kept constant as 3 m and the distance of excavation from the existing frame is varied as 1, 2, and 3 m. In all the cases the width of excavation is kept constant as 3 m. The finite element modeling and analyses are carried out using software. The parameters studied are displacement, stress distribution, frequency, mode shapes, and amplitudes.