Stability Assessment of Diaphram Cellular Cofferdams Subjected to Severe Hydro-structural Conditions

Background: Cellular cofferdams are a temporary construction consisting of interlocking steel sheet pilings driven into the ground as a series of interconnecting cells. Objectives: This study aims to investigate the stability of cofferdams with a circular diaphragm due to lateral load in dry and wet soil cases. Discussion: A series of laboratory tests were performed on different width to height ratios (0.8, 0.9, and 1.0), berm ratios (0.2H, 0.3H, and 0.4H), and embedment depth ratios (0.2H, 0.3H, and 0.4H) with four types of soil fill (clay soil, river sand, sand passing sieve No.4, and sub base). The coupled circular cofferdam-soil system was modelled using nonlinear finite element analysis (COMSOL Multiphysics Software) to validate the experimental results. Conclusion: After applying hydrostatic, hydrodynamic, and structural failure loads, the resistance of the cellular retaining structures with wet soil fill in saturated soils was greater than with dry soil fill in dry soils. The most advantageous construction format was found by deciphering the relationship between the aforementioned loads and berm ratios, embedment depth, and horizontal displacement.