Geotechnics and Infrastructure
Geotechnical Design and Ground Assessment
We select the foundation system from approved geotechnical investigation data, carry out the excavation support, liquefaction and ground improvement calculations to TBDY 2018 and draw the designs.
The work between the investigation report and the structural design
A geotechnical investigation report contains borehole logs, SPT values, shear wave velocity measurements and laboratory results, and most reports also include a foundation recommendation. Checking that recommendation by calculation against the actual loads of the structure, the basement depth and the neighboring buildings, and deciding how the excavation will be supported and whether the ground needs improving, is the job of geotechnical design. We carry out these calculations and draw the foundation, excavation support and ground improvement designs. We work for investors in residential, industrial and commercial buildings, contractors and public bodies.
In the 1999 Kocaeli earthquake, liquefaction, lateral spreading and shoreline collapses occurred in the coastal fills in and around Gölcük. In the loose sand and silty fills along the gulf shore, groundwater is still shallow today. Hillside settlements begin just behind the shoreline. Because the ground under two neighboring plots in the same district can behave very differently, we assess each plot with its own data.
Among the jobs we delivered in 2026, we designed ground improvement with deep soil mixing (DSM) columns for a multi-block service building to be built on soft clay. We designed jet grout columns for park structures to be built on uncontrolled fill on the shore. For the structures of a CNG station, we prepared the geotechnical report and the ground improvement design. In these jobs we assessed liquefaction and cyclic softening and calculated settlements with the finite element method.
Boreholes, SPT and other field tests, geophysical measurements, laboratory tests and the geotechnical investigation report are prepared by authorized firms and approved by the relevant authority. For the jobs above, too, we took the field data from the data reports of other authorized firms. We carry out the geotechnical design with this data, and coordinate with the firm doing the investigation so that the investigation program suits the structure.
Scope
Engineering interpretation of the investigation report
We read the soil profile, SPT and shear wave velocity data, the groundwater level and the laboratory parameters with design in mind. If data is missing or contradictory, we report it in writing.
Foundation system selection
Isolated, strip, mat or piled foundation. We compare the options by bearing capacity, total settlement and differential settlement, and where needed we calculate settlement with a finite element model.
Liquefaction and cyclic softening
We check the liquefaction potential in coastal fills and loose sandy sites, and the loss of strength during an earthquake in soft clays and silts. The foundation and improvement decision is made on this result.
Slope stability
On hillside plots and excavation slopes, we calculate the factor of safety separately for the static and seismic cases. If the result is inadequate, we propose drainage, a change in slope angle or a support structure.
Excavation support and deep excavation
Bored pile wall, sheet piling, prestressed anchors or soil nails. We choose the system by looking at the excavation depth, the foundations of neighboring buildings and the utility lines under the road.
Ground improvement
We compare jet grout, deep soil mixing (DSM) and stone column options with a piled foundation in the same table. The soil type, the depth to be improved, the structural load and the working space on site decide the choice. We also define the design basis of the chosen method and the verification tests after installation.
Applicable regulations and standards
We carry out foundation and ground calculations under the foundation design and ground provisions of the Turkish Building Earthquake Code (TBDY 2018). The local site class (ZA–ZF) is determined from shear wave velocity and field test data. Ground in class ZF, such as liquefiable soils, needs a site-specific assessment. We use TS 1500 for soil classification, TS 500 (the Turkish standard for the design of reinforced concrete structures) for reinforced concrete foundation members, and TS EN 1997-1 for the principles of geotechnical design. We write the relevant execution standards for piles and anchors into the design, and present the calculations in the form the authority and the building inspection firm require.
How we work
Preliminary assessment
From the preliminary architectural design, the location of the plot, the neighboring buildings and any earlier investigation data, we identify the geotechnical risks of the site.
Investigation program coordination
We send the authorized firm that will carry out the investigation, in writing, what the structure needs in terms of the number and depth of boreholes, field and laboratory tests and geophysical measurements.
Data evaluation
We select the design parameters from the data in the approved report and set the site class and the groundwater level to be used in design.
Calculations and options
We carry out the bearing capacity, settlement, liquefaction, slope and excavation support calculations. If more than one solution is possible, we set the technical results and approximate costs side by side.
Design and approval
We draw the foundation, excavation support and improvement sheets on the same grid lines and levels as the structural design, and work in the revisions from the authority and the building inspection firm.
Construction support
During excavation and piling, we compare the ground found on site with the design assumptions. If there is a difference, we revise the design.
Deliverables
- Geotechnical assessment and foundation system selection report
- Bearing capacity, settlement, liquefaction and cyclic softening calculation report
- Settlement analysis by the finite element method (where required)
- Slope stability calculation report (where required)
- Excavation support design (plan, sections, anchor and pile details, excavation stages)
- Ground improvement design basis and quality control testing program
- Recommendations for monitoring and measurement during construction
Frequently asked questions
Do you prepare the geotechnical investigation report?
No. The investigation report is prepared by authorized firms and approved by the authority. We talk to the firm so that the investigation program suits the structure, and carry out the geotechnical design with the data in the approved report.
Is a liquefaction assessment needed for a plot near the shore?
Yes, if the groundwater is shallow and the ground is loose sand or silty sand. This is common in the fill areas of Gölcük and along the gulf shore. In soft clays and silts we also check the loss of strength during an earthquake separately.
Mat or piled foundation?
That depends on the calculation. Bearing capacity, the expected total and differential settlement and the liquefaction result decide it. We calculate both options and write in the report which one we chose and why.
What should be done for a basement excavation next to a neighboring building?
The excavation support design comes first, and excavation starts after it. Depending on the depth and the ground, we design support with a bored pile wall, anchors or soil nails. The condition of the neighboring foundations and the order in which the excavation proceeds are shown separately in the design.
Which is more economical, ground improvement or a piled foundation?
The soil profile of the site decides that. If a wide area of soft clay has to be improved, DSM is often the suitable choice. When working in a tight space or close to an existing structure, jet grout comes forward, though its unit cost is higher. If the firm stratum is not very deep, a piled foundation may be more economical. We compare the options together with an approximate cost calculation.
Examples from practice
Our projects in this field
- Geotechnical report and excavation and shoring design for a wastewater treatment plantKocaeli / Körfez · 2025
- Wastewater treatment plant: DSM ground improvement and soil-nailed shoringKocaeli / Kandıra · 2026
- Multi-block service building: geotechnical report and ground improvement with DSMKocaeli / Kartepe · 2026
Request a quote for your project
Write to us with the type of building, its location and the documents you have. We will agree the scope and timeline with you and send a written quote.