The geotechnical engineering laboratory of the IIEES, which began its activities in 1993, is now recognized as one of the most advanced research centers in the country in the field of geotechnics. Relying on advanced and specialized equipment added to the facility in 1998 and 2005, this laboratory has played a significant role in enhancing technical knowledge and improving safety against geotechnical hazards, especially earthquakes.
The modern equipment in this laboratory enables precise examination of the dynamic behavior of soils under dynamic loading and determination of key parameters for seismic hazard analysis and resilient seismic design. The center’s capabilities are focused on two main areas: laboratory testing on soil samples (element tests) and geophysical field testing.
This diversity in methods and equipment allows for a wide range of specialized tests to meet research and industrial needs. As a result, the laboratory is not only recognized as a scientific reference in geotechnical research but also contributes significantly to improving the quality and safety of civil engineering projects by offering its specialized services to the industry.
Tests such as grain size distribution, Atterberg limits, compaction, shear strength, consolidation, and more advanced tests like triaxial and direct shear provide quantitative and qualitative information about the physical, hydraulic, and strength properties of soil. These data form the basis for modeling soil behavior under various loading conditions, evaluating geotechnical stability, selecting foundation type and depth, and designing soil stabilization systems.
Geophysical methods, compared to other ground investigation techniques such as drilling, offer advantages due to ease of use and non-intrusiveness. These methods provide extensive data both at depth and near the surface in a shorter time, which, when combined with other ground investigation results, lead to more comprehensive information.
This collection includes various devices and tools used to assess physical characteristics (such as grain size distribution, Atterberg limits, density, and porosity) and soil strength properties (such as shear strength, compressibility, and permeability). Examples include:
These tests are essential in geotechnical engineering, foundation design, dam construction, road building, and other civil structures, helping engineers predict and analyze soil behavior under different loads.
This advanced geotechnical system allows for both static and dynamic testing, enabling precise analysis of soil behavior. With 8 independent auxiliary cells, it can conduct multiple tests simultaneously and apply confining pressures up to 2 MPa (20 bar) and axial pressures up to 10 MPa (100 bar) with ±0.1% accuracy.
Key applications include:
The main advantage of using 8 auxiliary cells is increased efficiency and reduced testing time through simultaneous testing and result comparison. This device complies with international standards ASTM D2850, ASTM D4767, and ASTM D7181 and is considered essential for geotechnical identification and engineering design.
This device creates controlled vibrations to determine the minimum void ratio (lowest ratio of void volume to total volume) in granular soils like sand and gravel. By placing the soil sample in a special chamber and applying vibrations with specific frequency and amplitude, the soil particles reach their densest possible state.
Key applications include geotechnical studies for road construction, dam building, and foundation design, as the compressibility and strength of granular soils are directly related to their void ratio. This test is conducted according to international standards such as ASTM D4254.
These devices are standard laboratory equipment for determining soil shear strength parameters including cohesion (c) and internal friction angle (φ). The direct shear device consists of a box divided into two halves, with the soil sample placed between them. Under constant vertical stress, shear stress is applied.
The direct shear test is conducted according to international standard ASTM D3080. Its main advantage is ease of execution and relatively low cost compared to other methods for determining soil shear strength.
These devices are specialized geotechnical laboratory equipment used to study the consolidation behavior of fine-grained soils under incremental axial loading. The uniaxial consolidation apparatus (oedometers) at IIEES apply compressive pressures up to 64 kg/cm² to interpret the consolidation properties, such as pre-consolidation stress, compression ratios, rates of deformation, and so on.
Other important uses include:
These tests are primarily conducted according to ASTM D2435 standards.
This device is used to determine the unconfined compressive strength of cohesive soils such as clays. In this test, the soil sample is subjected to axial compressive loading without any lateral confinement until failure. By measuring compressive strength and stress-strain behavior, engineers can estimate resistance parameters like cohesion. This device is especially useful in geotechnical studies and construction projects requiring rapid soil strength evaluation.
One of the most efficient tools to measure soil properties at small-strains. The device can measure shear modulus (G) and damping ratio (D) of soil samples at very small strains (10⁻⁶ to 10⁻⁴). A cylindrical soil sample is subjected to a desired consolidation stress and vibrated at various frequencies to determine its resonant frequency. Shear stiffness is calculated from the resonance frequency.
This device examines soil behavior under complex dynamic loads. It uniquely allows the hollow soil sample to experience four degrees of freedom (axial, vertical, diagonal, and torsional), with independent variation of each principal stress component. Analyzing results requires technical expertise and is mainly used in research studies.
Designed for studying soil behavior under cyclic axial and lateral loading. It enables cyclic triaxial testing and includes six auxiliary cells for preparing multiple samples—especially valuable for time-consuming saturation and consolidation processes in fine-grained soils.
Unique features such as precise pore pressure control, volume change measurement, and continuous data recording make this device interesting for advanced geotechnical research.
Beder elements allow for measuring shear wave velocity (Vs) and calculating small-strain shear modulus (Gmax) of soil. A pair of piezoelectric elements (transmitter and receiver) are installed at both ends of the soil sample, and shear waves are transmitted to accurately measure dynamic soil properties. However, the bender elements remain in the sample during subsequent large-strain loading
