Large diameter piles have increasingly been used, especially for offshore foundations. Most of the piles that have been used offshore have been open-ended. There is evidence from previous work that closed-ended piles have merits over open-ended piles; they have a greater ultimate axial capacity and are easier to drive than open-ended piles of the same outer diameter. However, because a greater volume of soil is displaced, closed-ended piles give rise to much greater ground heave. This additional heave may cause unacceptable distortion to the structure as each leg is fixed to the sea-bed in turn. For this reason, this research was commissioned. Laboratory studies of ground heave around driven open- and closed-ended piles (16mm o.d.) were carried out. Two different types of specimen reconstituted from Speswhite Kaolin were prepared; semi-cylindrical and full cylindrical specimens each 450mm in diameter and about 450mm in height. The semi-cylindrical specimens were used to obtain qualitative data about the movements of soil around the driven pile. The full cylindrical specimens were used to take accurate measurements of the ground heave during pile driving and to study the influence of the ground heave on a small surcharged collar through which a pile was driven. A further series of tests investigated the effect of ground heave when a group of piles was driven through a larger surcharged collar which was used to represent the mudmat of an offshore structure. The lateral movement of soil at around the mid-depth of a driven pile agreed with the cavity expansion model (plane strain analysis) assuming undrained conditions and no vertical movement. Closed-ended piles were found to generate about four times the magnitude of ground heave compared to open-ended piles with an area ratio of 34%. Ground heave appeared to be unaffected by overconsolidation ratio and rate of pile driving (22 to 150 blows/min.). However, maximum vertical consolidation pressure seemed to have a small effect. A remarkably good agreement was obtained between the field data and the results of this investigation when both were made dimensionless. The surcharged collar and model mudmat generally settled during pile driving. However, when very low surcharge pressures were used, the collar and mudmat were lifted up. For pile groups, the surcharged mudmat tilted towards the pile being driven. The magnitude of this tilt for the mudmat was greater when closed-ended piles were used.

The results of a series of over 120 model tests to study the end bearing capacity of piles in layered calcareous soils are described. The tests were carried out on samples enclosed in a cylindrical testing chamber, 450 mm diameter and 450 mm high, which allowed independent control of horizontal and vertical stress in the range 25 kPa to 500 kPa. The samples consisted of a loose, uncemented calcareous sand consisting predominantly of foraminifera and mollusc micro-organisms (D50 = 0.2 mm, calcium carbonate content 92%). Into this was built a layer of the same material artificially cemented by a gypsum plaster. The layer had similar properties to naturally cemented deposits, and layers with unconfirmed crushing strengths in the range 500 kPa to 4000 kPa have been prepared. All samples were tested dry. Closed end model piles of 16mm diameter were jacked at 0.1mm/s into the sample, and continuous profiles of end bearing capacity obtained during penetration. A parametric study has been carried out to examine the effects on the bearing capacity of stress level, K0, cemented layer thickness (0.5 pile diameters to 5.0 pile diameters) and layer strength. In addition, tests have been conducted with different pile geometry, multiple cemented layers, and using dynamic installation techniques. The study has identified ranges of parameters for which brittle failure of the cemented layer occurs (low stress levels and high layer strengths) and ranges where the failure is ductile (high stresses and low layer strengths). Characteristic patterns have been observed of the variation of end bearing with position as a layer is penetrated. Examination of the samples after testing has revealed details of failure mechanisms. Simple procedures are proposed for modelling the bearing capacity of such layered systems, and some implications of the results for design methods are discussed.

An instrumented model pile was used to investigate the fundamental behaviour in clay soils of driven cylindrical steel piles used for offshore structures. Four test-bed sites were chosen; two in stiff heavily consolidated clays, and two in normally/lightly overconsolidated clays. Data from these sites confirm that a residual shear surface is formed along the pile during installation, the location of which relative to the shaft surface appears to depend on the shaft roughness. Comparisons with other site investigation data and cavity expansion theoretical predictions indicate that stress relief immediately behind the pile tip during driving gives rise to total radial stresses and pore pressures measured on the pile shaft which are lower than predicted. This stress relief is particulary severe in the stiffer clays. The data did however show that the installation total radial stresses and pore pressures are governed by the initial in-situ stresses and undrained shear strength as is predicated by the theory. During reconsolidation, pore pressures close to the instrument rise initially in all clays, and radial effective stresses drop. The slow recovery in radial effective stress during the later stages of reconsolidation was in some cases insufficient to return it to levels recorded during installation. However, the generation of negative pore pressures during undrained loading increased the radial effective stress and shaft friction at failure. This effect is particularly important in the normally consolidated clays, and is responsible for the set-up of shaft capacity seen in such clays, which might not be observed if the loading were drained. The observed behaviour was therefore quite different from the monotonic increase in radial effective stress during reconsolidation, followed by decrease during undrained loading which was expected from a review of current theory.

The topic of my master`s thesis is to design foundations of multifunctional building in Olomouc. Another part of this master`s thesis deals with safe and economic design solution of shoring wall. This construction is used to built underground parts of the building. The last part of the work contains description of technological proces of the geotechnics constructions execution. The drawing documentation is also included.