The need for construction of excavations in urban areas requires control of the surrounding ground since excessive ground movements damage adjacent properties. Construction of an excavation inevitably induces lateral movement and settlement of the ground which can have detrimental effects on adjacent buildings. Braced excavation is commonly involved in the construction for basements of high-rise buildings, stations of underground traortation systems, and underground parking spaces. Construction of a braced excavation system inevitably induces lateral movement and settlement of the ground which can have detrimental effects on adjacent buildings. Past studies of building response to ground displacement have primarily dealt with the tolerance of buildings to settlement under their own weight and disregarded the effect of excavation , So studeis in the field of buildings settlement due to excavation seems to be necessary. In this thesis A series of 2D ?nite element analyses were performed using a commercial ?nite element program PLAXIS to examine the building movement characteristics. The comparison between the emprical method and the Plaxis results for critical height is presented and the effects of cohesion, friction angle and unit weight was studied on critical height. Critical height increases with cohesion and friction angle and decreases with unit weight. Building , s settlement under their own weight was in elastic phase and according to Mohr-Coulomb model the elastic parameters(i.e. young , s modulus and poisson , s ratio) effect on it and in the other hand on buildings settlement due to excavation all parameters of Mohr-Coulomb model are effective. We also studied the effect of soil, excavation, diaphragm wall,building and struts , parameters on buildings settlement. The effect of mohr-coulomb parameters on building , s settlement showed that in both elastic and plastic phases, vertical displacement due to excavation decreases with increasing in young , s modulus. With increasing in poisson , s ratio, in elastic phase vertical displacement due to excavation decreases and i plastic phase is vise versa. With increasing in cohesion, friction angle and Dilatancy angle, vertical displacement due to excavation increase and i plastic phase is vise versa. In elastic phase vertical displacement due to excavation decreases with increasing in the width of building and the number of building , s stories, and increases with increasing in the number of building , s in plastic phase.
