Geotechnical and Geodetic Surveys in Ganja

Engineering geological conditions in Ganja

Ganja lies at the north-eastern foot of the Lesser Caucasus on the Ganja–Gazakh inclined plain. The land descends gradually from the foothill belt in the south-west towards the Kura depression in the north-east. The Ganjachay river crosses the city, and its valley and terraces are the main feature of the urban relief. Overall the terrain is gentle, but locally steep banks occur along the river, irrigation canals and gullies.

The ground consists mainly of alluvial fan deposits of rivers descending from the mountains: gravel and pebbles, coarse soils with sandy infill, overlain by loess-like loams and sandy loams of varying thickness. Close to the Ganjachay the gravels come near the surface; further from the river the clayey cover may thicken. On some sites the loams may contain carbonate and gypsum inclusions; their presence is established by laboratory analysis.

The older parts of the city contain cultural layers and made ground accumulated over centuries, which may conceal remains of ancient buildings, wells and kahrizes (traditional underground water channels).

Key construction risks in Ganja

• Collapsible soils. Loess-like loams formed in a dry climate look reasonably strong at natural moisture, but when wetted they may settle further under their own weight or the foundation load. This most often shows up after leaks from water pipes, irrigation or rainwater ponding around a building. Collapsibility can only be determined by laboratory testing.
• Variable gravel foundation soil. Gravels contain lenses of sand and clay, and the top of the layer lies at different levels. This can lead to differential settlement and calls for a denser borehole grid.
• Groundwater. In the Ganjachay valley and on irrigated land the water table is relatively shallow, while in the upper parts of the city it is deeper. During the irrigation season and with canal leakage the level rises and may wet collapsible soils.
• Kahrizes and underground voids. In historic cities, old kahriz galleries and wells are often discovered unexpectedly during construction; a foundation placed over them suffers local settlement.
• Seismicity. The Ganja area is historically known for strong earthquakes and belongs to a seismically active zone. The design seismic intensity is taken from the applicable standards and codes and refined for the ground conditions on site.

The practical consequence for the designer is to establish the type of collapsibility. If collapse occurs only under foundation load, correctly sizing and embedding the foundation and draining water away from the building is often sufficient. If the soil collapses under its own weight as well, the solution becomes more complex: compaction, cutting through the collapsible stratum or a piled foundation may be required. The choice is based on the collapsibility indicators and the thickness of the collapsible stratum given in the report.

Surveys typically required

The key questions in Ganja are the thickness and collapsibility of the loess-like stratum and the depth of the gravel foundation soil. Usually the following are carried out:

• borehole drilling and sampling, with undisturbed samples from the loess-like stratum;
• where the clayey cover is thin, dynamic probing to trace the top of the gravel;
• mechanical properties — oedometer tests and collapsibility assessment with wetting;
• physical properties and chemical analysis of soil and water;
• groundwater level and regime, especially next to irrigated land;
• in the old city, ground penetrating radar (GPR) or an electrical resistivity survey to detect voids and kahrizes;
• where existing buildings show cracks, a foundation soil investigation for existing buildings.

Once the foundation pit is excavated, a foundation pit inspection confirms that the actual ground matches the report.

How the work is organised

During the site visit we check the terrain, irrigation canals, remains of old structures and rig access. Drilling slows down in gravels and tools wear faster, which determines the schedule and the choice of equipment.

Preserving the natural moisture of undisturbed loess-like samples is especially important: if it changes, the collapsibility test result is distorted. The samples are therefore sealed airtight on site and sent to the laboratory promptly. Distance affects the price through equipment transport, crew accommodation and sample shipping; combining several projects in one trip can reduce these costs. To get a price, send a quote request.