Three-dimensional analysis of improving the reliability and serviceability of truss guard structures in terms of side bracing effects

ABSTRACT Truss guard structures are considered as one of the main options in excavation projects due to their lower cost, easier execution and less need for executive specialized personnel. Examination of the experiences of damages caused during excavation with truss guard structure shows that the defects in the joints and the lack of adequate lateral restraints are among the main reasons for the failure of these guard structures and instability in the excavations. One of the main reasons for not paying enough attention to lateral restraints in excavation projects is the use of two-dimensional flat strain analysis in the design process. In these analyzes, the forces perpendicular to the plane are not calculated, so the design of lateral restraints is based solely on the designer's experience. In this paper, using ۳D plexiglass finite element software, and modeling of a ۷ m high hollow wall, the effects of lateral bracing on reliability coefficients and displacements occurring in service conditions are investigated. Also, three-dimensional analyzes are performed. It has been shown that the use of lateral restraints increases their stability coefficients with the truss guard structure and leads to a reduction in deformations of service conditions.