Earth pressures on caissons in marine clay under lateral loads — A laboratory study

This investigation refers to an experimental study on earth pressure mobilization in caissons embedded in soft clay. Based on the results, a contiguous wall made up of embedded caissons in soft clay is proposed to serve as a coastal protection wall. Tests were conducted on model caissons embedded in stiff marine clay. Lateral load tests were carried out on models with embedment depth ratios of L/D=2,3L/D=2,3 and 4 at load eccentricity ratios of e/De/D of 0.5, 1.0, 1.5 and 2.0. Earth pressure cells were embedded into the caissons at various depths. Using a pneumatic type of arrangement, controlled lateral loading was applied. The test results show that these caissons can be loaded to produce lateral deflection in the ratios of 30%–35% expressed in terms of diameter. The capacities are estimated corresponding to lateral deflection ratios of 20%. These results suggest that the lateral capacity is a function of undrained strength (susu), embedment depth ratio (L/DL/D) and load eccentricity ratio (e/De/D). There is a good correlation between lateral load and the maximum earth pressure mobilized. At a higher L/DL/D ratio of 4, the lateral earth pressure is found to be unique function of lateral load irrespective of e/De/D. A unique relation is established between lateral load and deflection in the normalized form. This relation matches very well with the published field lateral load deflection curves.