Geotechnical investigation and testing – Albatros 2 Hotel in Cavtat
The construction of a new Albatros 2 Hotel building is planned on a plot of about 50 thousand square meters near the town of Cavtat, about 850 meters from the historic center between the Žal Promenade and Put od Oboda Street.
Planned works
Sports courts and the existing Albatros 1 Hotel built in the seventies sit next to the future Albatros 2 Hotel.
The future building for catering and tourism purposes will cover 16.400,88 square meters and have a total of 3 above-ground and 1 underground floor with a total of 252 accommodation units. The design by the architects from Studio 90 plus / Dizarre kreativna arhitektura fits perfectly into the spatial ambience. The form of the building is fragmented into smaller blocks permeated by green corridors and all accommodation units have a view towards the sea shore. The basic construction system consists of AB walls.
Geotechnical investigation and testing
Geotechnical and engineering geological investigation and testing were carried out in February 2021 and included:
- geological and geotechnical prospection of the wider area;
- excavation of probing pits;
- concrete strength tests;
- exploratory drilling;
- standard penetration tests;
- engineering geological mapping of the terrain and determination of drilling cores and boreholes;
- geophysical surveys;
- laboratory testing of samples from boreholes.
The Velika Rijeka river canal passes through the existing location. Three probing pits were executed to determine the depth of the foundation and the position of the canal. The probing pits were also used to determine the geotechnical profile of the investigated location.
In cooperation with the Institut IGH from Split, we carried out the testing on the construction of the channel in order to determine the condition of the reinforcement, the compressive strength of concrete and the depth of carbonation in the surface layer of concrete. Determining the quantity, diameter, type, layout and condition of the reinforcement using a combination of destructive and non-destructive methods was performed at selected construction sites. This included concrete stripping and inspection of the reinforcement for corrosion, inspecting a part of the structure with non-destructive reinforcement device, measuring reinforcement diameter at points where the concrete was beaten off, and measuring the spacing of the reinforcing bars.
In the scope of the geotechnical investigation and testing, four rotary boreholes (individual lengths of 12.0 to 15.5 m and total length of 55.0 m) were drilled. The boreholes were used to determine the geotechnical characteristics of the location and the foundation soil. The drilling was conducted with continuous coring along the entire depth of the borehole.
As part of the geotechnical investigation and testing, geophysical tests of shallow seismic refraction of P-waves (Delta-t-V-method) with a total length of 993 m were also conducted.
In parallel with the engineering-geological mapping of the terrain and the execution of investigation and testing, geotechnical prospecting was carried out, in order to determine the geotechnical units of the same physical and mechanical characteristics, and to establish the geotechnical profile of the investigated location.
The conducted laboratory soil tests included the soil density test, the Atterberg limits, the determination of the shear soil strength and the soil compressibility test by an edometric experiment.
Geotechnical feature of the location
The conducted investigation and testing and the geotechnical prospecting of the terrain established that the location consists of three lithostratigraphic units and the Eocene limestone bedrock covered with deposits of made ground and alluvium. Alluvial deposits were brought by the canalized watercourses Mala and Velika Rijeka.
The spatial arrangement of geotechnical units and the position of the future object is shown in the geotechnical section. The section gives a clear insight into the conditions of the foundation soil below the object.
Archaeological excavations at the location
An archeological site was found next to the location of the future Albatros 2 Hotel, where parts of prehistoric objects were explored. The archeological units attributed to the medieval period were isolated.
Archeological excavations were conducted in parallel with the investigation and testing for the future Albatros 2 Hotel. The remains of border walls, villa rustica and parts of mosaics were found.
The Roman villa is a building built during the Roman Republic and the Roman Empire and was originally a Roman country house for members of the upper-class. Later, the Roman villa evolved into two types: the villa urbana which represented the center of the rural estate and the villa rustica which represented the rural household in which the members of the lower classes resided.
Design guidelines
After the geotechnical investigation and testing, recommendations for the foundation soil arrangement and foundations were established. A shallow foundation with a combination of AB slab foundations and strip foundations on a rock embankment in geotechnical unit 1 – Alluvium was selected. The planned foundation evenly distributes the bearing surface and keeps the soil compaction within acceptable limits.
Read more: Types of shallow foundations
