Seismic performance of deep excavation restrained by guardian truss structures system using quasi-static approach

Abstract

The control of deformation and stability of the deep excavation walls under seismic and static loads is one of the most important issues in geotechnical engineering. Therefore, in the present study, using the finite element method and taking into account Hardening soil's behavioural model, the effect of different parameters affecting the performance of the deep excavation walls with the guardian truss structures using quasi-static analysis and its comparison with static analysis has been performed. According to the most important results, increasing in the geotechnical parameters of soil such as cohesion, friction angle and elastic modulus will reduce the maximum horizontal displacement in the vertical trench wall. Besides, the maximum settling in the adjacent ground and the maximum swelling in the bottom of the excavation will be reduced. In this way, the improvement in soil resistance parameters will increase the safety factor. Conversely, by increasing the horizontal distance between the trusses, the maximum horizontal displacement and the maximum settling in the adjacent ground and the maximum swelling in the bottom of the excavation will increase and the safety factor will be reduced. Also, the findings from this research show that by increasing the horizontal seismic acceleration coefficient (Kh) and as the construction stages progress, the maximum horizontal displacement of the wall, the maximum settling of the adjacent ground of the wall and the maximum swelling on the bottom of the trench increase and the safety factor will decrease. As well as, the results obtained from the quasi-static seismic analysis of the vertical trench restrained by the guardian truss structure such as the maximum horizontal displacement of the vertical trench wall and the maximum settling in the adjacent ground and the maximum swelling of the bottom of the excavation are much more than the static analysis.