Mechanical characteristics of counterfort-relief shelf composite retaining wall.

A counterfort–relief shelf composite retaining wall is capable of reducing lateral earth pressure. With its relief shelf and T-shape variable section beam as tension member, this wall is effective for high fill slope engineering; however, research on this type of retaining wall is limited. Moreover, investigating the lateral earth pressure distribution law and the mechanical and deformation characteristics of this composite structure is necessary. In this study, three models (a counterfort structure, structure with short relief shelves, and structure with long relief shelves) were tested. Moreover, lateral earth pressure, bending stress, and structural displacement were measured. The measurements revealed that the lateral earth pressure, bending stress in the buttress, and displacement of composite structures were less than those of the counterfort retaining wall under the same conditions. The present study reveals that relief shelves can reduce the total lateral force, maximum bending moment, and maximum displacement at the top of the structure by 33%, 30%, and 33%, respectively, compared with those of the counterfort wall. The lateral earth pressure acting on the structure with long relief shelves is significantly lower than that on the structure with short relief shelves. However, in terms of bending stress and displacement, the difference is not evident. The lateral earth pressure under each relief shelf starts from zero and follows a certain distribution law. Although the relief shelf can reduce the magnitude of lateral earth pressure, it raises the point of application of the total lateral force. Thus, the length and position of the relief shelf are important governing factors of the bending moment of a composite structure. Due to variations in the bending moments derived from the tests, theoretical lateral earth pressures, and calculated bending stresses in the buttress, this study hypothesizes that a certain force is exerted on the lower part of the unloading zone, thus requiring further research. The displacement curve of the composite retaining wall is similar to that of the counterfort retaining wall; it conforms to the bending deformation of the cantilever beam. [ABSTRACT FROM AUTHOR]