This article presents a study on large diameter thin cylindrical shells filled with soil. The theoretical model is developed for the subsoil stability assessment of the researched structures based on the subsoil boundary state of stress solution using failure slip surfaces. The theoretical model relates foundation soil parameters and structure dimensions to maximum horizontal force, which might be held by the structure without loss of its subsoil bearing capacity. The model developed to predict maximum load can be used to estimate impacts made by various factors, such as ice, waves, docking, mooring, and lateral earth pressure, on these shell structures.
For engineering solutions various supporting structures are used in the design of berths, docks, break walls, and in retaining walls supporting foundations of trestles and bridge piers. An alternative solution to the two extremes of built-in soil thin walls and heavy gravity structures is a large diameter shells consisting of thin shell (made of steel or reinforced concrete) with infill of certain physical and strength properties. The shells have considerably large diameter of several meters with small wall thickness of few centimeters. The structure's diameter (D) to its height (H) ratio, D/H, are within the range of 0.7 to 1.0 for these structures.
Economically these structures are relatively cost-effective and have several advantages during the constructions. For example, the shell itself can be manufactured both as monolithic and sheeting planks driven into the ground. Conditionally, these shells can be divided into two main groups: first - shells installed on incompressible bed (Fig. 1) and second - partially undergrounded shells (Fig. 2). The first group shells are usually installed on specially prepared layer of structural fill ("incompressible bed").
Manufacturing and quality control of such special foundations is quite difficult as, in most cases, the shells are installed in water and the works is handled in rough environment. Moreover, in many cases height requirements result in considerably large shell diameters and then the weight of the shell may exceed lifting capacity of cranes. These factors determine conditions for the construction of infilled shells partially grounded into foundation.
