Yielding mechanisms in a rectangular trench

In geotechnical engineering, stability of the openings formed by excavation is of much concern in controlling the design feasibility and construction workability of underground structures. Analysis of the stability of the excavated openings and the corresponding measures against instability inevitably necessitate a good understanding of the yielding and failure mechanisms of the openings. This paper proposes a mechanism of potential yielding across an excavated rectangular diaphragm wall panel trench. By using an elastic analytical solution to the problem of horizontal stress changes and displacements induced during the installation of a rectangular diaphragm wall panel, two extreme cases (panel trenches with dimensions 1 m × 1 m and 6 m × 1 m) have been analysed to investigate the distribution of the principal stress change of the soils around the trenches due to excavation. It has been found that, when the elastic limit is reached, soils with different consolidation histories will exhibit different yielding modes—either active yielding around the faces of the excavated trench for normally consolidated soils or passive yielding around the ends of the excavated trench for overconsolidated soils. The proposed mechanism has been supported by some reported experimental results.