Introduction
A geotechnical investigation determines the engineering properties of the soil and rock beneath a proposed structure, informing foundation type, depth, and design loading. Skipping or under-scoping this step is one of the most common causes of foundation-related defects and cost overruns in construction projects across Saudi Arabia's varied ground conditions — from coastal sabkha soils to deep desert sand and rock formations.
Importance of Site Investigation
Soil conditions vary significantly across Saudi Arabia, from collapsible and saline soils in coastal and low-lying areas to dense rock formations in the central and northern regions. A geotechnical investigation gives designers the actual ground data needed to select an appropriate foundation system rather than relying on generic assumptions that may be unsuitable for the specific site.
Soil Sampling
Disturbed and undisturbed soil samples are recovered at intervals throughout each borehole for laboratory analysis. Undisturbed samples preserve the soil's natural structure and are used for strength and consolidation testing, while disturbed samples support classification and index property testing.
Boreholes
Boreholes are drilled to depths determined by anticipated foundation loads and local geology, typically using rotary or auger drilling methods. Each borehole is logged in detail, recording soil and rock strata, groundwater level, and sample recovery at each depth interval.
Standard Penetration Test (SPT)
SPT is performed at regular intervals within each borehole, measuring the number of blows required to drive a standard sampler into the soil. The resulting N-value correlates with soil density and strength, forming a key input for foundation bearing capacity calculations.
Laboratory Testing
Recovered samples undergo laboratory testing to determine engineering properties relevant to the project's design requirements, covering classification, strength, and compressibility characteristics of the soil profile.
Rock Coring
Where rock is encountered at shallow depth, rotary core drilling recovers intact rock cylinders for assessment of rock quality, strength, and fracture characteristics, which inform foundation design on rock-bearing sites.
Groundwater Investigation
Groundwater level and behavior significantly affect foundation design, excavation methodology, and construction sequencing. Monitoring wells and piezometers may be installed to track groundwater levels over time where seasonal variation is a design consideration.
Engineering Report & Recommendations
All field and laboratory data is compiled into a geotechnical engineering report presenting soil profiles, test results, and specific foundation recommendations — including allowable bearing capacity, settlement estimates, and any ground improvement requirements identified during the investigation.
Borehole Drilling Capabilities
- Geotechnical Boreholes — standard foundation design investigation
- Environmental Boreholes — contamination assessment and remediation planning
- Monitoring Wells — long-term groundwater level and quality tracking
- Core Drilling — intact rock and soil sample recovery
- Rotary Drilling — efficient penetration through mixed soil and rock
- Auger Drilling — rapid shallow investigation in cohesive soils
Soil Testing Capabilities
- Moisture Content
- Atterberg Limits
- Compaction Test
- California Bearing Ratio (CBR)
- Triaxial Test
- Shear Strength Test
- Consolidation Test
- Permeability Test
- Grain Size Analysis