Experimental investigations on a deep excavation support system with adjustable strut length

Abstract

Conventional deep excavation support systems (diaphragm wall with inner strut) have fixed length of struts, which can lead to a significant discrepancy between deformations of actual and designed diaphragm wall systems. As a result, failure of support system is likely to occur during the deep excavation. In this paper, a novel deep excavation support system with adjustable strut length was proposed, whereby the construction risk during deep excavation can be effectively reduced. An intelligent adjustment method of coordinated deformation of deep excavation support system was proposed as well. Model tests were carried out to investigate the influence of inner strut length on the mechanical and deformation characteristics of the system consisting of inner strut, diaphragm wall and soil behind diaphragm wall. The inner strut forces, lateral earth pressure on the diaphragm wall, the ground settlement and the deformation of the diaphragm wall were measured and analyzed. Results show that control the horizontal displacement of the braced excavation strictly will lead to the increment of axial force and the axial compression ratio of strut, which pose a threat to the safety of the strut system. By contrast, a reasonable adjusted length of inner strut is favorable to the safety of construction.