Drones are increasingly being utilized in CREATE Team for geotechnical investigations to enhance efficiency, accuracy, and safety in data collection. Equipped with high-resolution cameras, LiDAR, thermal, and hyperspectral sensors, drones are widely used to survey large or inaccessible areas, capturing detailed surface and environmental data without the need for extensive ground operations. Hyperspectral imaging, in particular, allows for the identification of different soil and mineral types based on their spectral signatures, aiding in more precise site characterization. This aerial data supports the planning and execution of subsurface investigations by identifying potential hazards, mapping geological features, and monitoring site conditions over time. When integrated with traditional geotechnical methods, drone technology significantly improves the quality of data for risk assessment and project planning.

Electrical Resistivity Imaging (ERI), also known as Electrical Resistivity Tomography (ERT), is a widely used geophysical technique for investigating subsurface conditions by measuring the soil or rock’s resistance to the flow of electrical current. The method involves inserting multiple electrodes into the ground in a linear or grid pattern and injecting a low-voltage electrical current through selected pairs of electrodes while measuring the resulting potential differences across others. These measurements are then used to calculate the apparent resistivity of the subsurface materials. Since different geological materials—such as clay, sand, rock, or water-saturated zones—have distinct resistivity values, ERI can effectively map variations in subsurface composition, structure, and moisture content. This makes it particularly valuable for identifying groundwater levels, detecting voids or sinkholes, mapping bedrock depth, and assessing contamination plumes. In geotechnical investigations, ERI offers a non-invasive, cost-effective method for obtaining high-resolution 2D or 3D images of the subsurface, which aids in risk assessment, foundation design, slope stability analysis, and environmental studies. Its adaptability to various site conditions and ability to cover large areas make it a powerful tool for preliminary site investigations and ongoing monitoring.

Multichannel Analysis of Surface Waves (MASW) is a widely adopted, non-invasive geophysical method used to evaluate the shear wave velocity (Vs) profile of the subsurface, which is directly related to soil stiffness and plays a critical role in seismic site response and geotechnical engineering. The technique involves generating surface (Rayleigh) waves using a controlled seismic source—such as a sledgehammer or mechanical vibrator—and recording their propagation using a linear array of geophones (typically 24 or more channels). The key advantage of MASW lies in its ability to analyze the dispersive behavior of surface waves: different frequencies penetrate to different depths, and by measuring the change in wave velocity with frequency (dispersion), it is possible to infer the variation in shear wave velocity with depth. The result is a 1D, 2D, or even 3D velocity model of the subsurface that provides insights into stratigraphy, stiffness contrasts, and potential weak layers. MASW is particularly effective in characterizing soft sediments, locating bedrock depth, and evaluating ground response for earthquake hazard analysis. Compared to invasive methods, it is quick to deploy, cost-effective, and well-suited for urban and sensitive environments. It is widely used in site classification (e.g., for determining Vs30), foundation design, road and pavement studies, and other applications where understanding subsurface stiffness and layering is critical.

Ground Penetrating Radar (GPR) is a high-resolution, non-invasive geophysical method used to investigate shallow subsurface features by transmitting high-frequency electromagnetic waves into the ground and recording the reflected signals from subsurface interfaces. The system typically consists of a control unit, transmitting and receiving antennas, and a data acquisition device. As the radar waves encounter materials with contrasting dielectric properties—such as soil layers, voids, buried objects, or moisture—they are partially reflected back to the surface, where they are detected and recorded. GPR is especially effective in mapping shallow subsurface conditions (typically up to 10–15 meters depth, depending on soil type and antenna frequency), making it highly valuable in geotechnical, environmental, archaeological, and forensic investigations. In geotechnical applications, GPR is used to locate utilities, detect voids and sinkholes, assess pavement conditions, and map rebar or structural elements in concrete. It is also helpful in identifying changes in soil stratigraphy, groundwater tables, and other anomalies. One of the key advantages of GPR is its ability to provide real-time, continuous data with minimal site disturbance. However, its effectiveness can be limited in clay-rich or highly conductive soils, where signal attenuation is high. Despite these limitations, GPR remains a versatile, rapid, and cost-effective tool for shallow subsurface exploration and monitoring.

Large Diameter Consolidation (LDC) testing is an advanced laboratory method used to evaluate the compressibility and consolidation behavior of soils, particularly soft clays and silts, under more representative stress and drainage conditions than those provided by conventional oedometer tests. Unlike standard consolidation tests, which typically use small specimens (usually 50 mm in diameter), LDC tests use significantly larger soil samples—often 150 mm or more in diameter—allowing for better representation of in-situ conditions, including fabric, layering, and natural heterogeneity. This increased size also reduces the scale effects and boundary constraints that can influence test results in smaller samples. LDC testing is especially valuable in the design and analysis of large-scale geotechnical projects such as embankments, land reclamation, and foundations on soft ground, where accurate prediction of settlement and rate of consolidation is critical. The test provides key parameters such as the coefficient of consolidation (Cv), compression index (Cc), and preconsolidation pressure, which are essential for settlement analysis and time-rate calculations. Additionally, with appropriate instrumentation, LDC setups can monitor pore water pressure dissipation and vertical strain continuously, offering deeper insight into soil behavior during loading. Overall, Large Diameter Consolidation testing provides a more realistic and reliable assessment of compressibility characteristics for critical geotechnical designs involving soft or sensitive soils.

Field-Scale Direct Shear Testing is a geotechnical testing method used to determine the shear strength parameters of soil or rock interfaces under in-situ conditions, offering a more realistic assessment compared to laboratory-scale tests. Unlike standard laboratory direct shear tests, which are performed on small, remolded or disturbed samples, the field-scale version involves testing large soil blocks or natural surfaces directly at the site. This allows engineers to capture the true behavior of the soil, including natural structure, layering, moisture content, and potential weak planes that are often lost or altered during sample extraction and handling. The test typically involves applying a normal load to a large shear box or reaction frame placed on or around the soil mass, followed by controlled horizontal shearing to measure the soil’s response. Key parameters obtained include cohesion (c), angle of internal friction (φ), and shear strength under specific normal stresses. Field-scale direct shear tests are especially useful for assessing slope stability, embankment performance, and the shear strength of interfaces such as those between soil and geosynthetics or rock discontinuities. Though more time-consuming and logistically demanding than laboratory tests, field-scale shear testing provides critical, site-specific data that enhances the reliability of geotechnical designs, particularly in complex or sensitive soil conditions where accurate shear strength values are essential for safety and performance.

Triaxial testing equipment is a fundamental component in geotechnical laboratories, used to determine the mechanical properties and strength behavior of soils under controlled stress conditions. The apparatus typically consists of a cylindrical chamber (triaxial cell) where a cylindrical soil specimen, usually enclosed in a rubber membrane, is subjected to confining pressure through a fluid medium. Axial load is then applied vertically through a loading piston, allowing the sample to be sheared under controlled stress paths. Triaxial tests can be conducted in various forms—unconsolidated undrained (UU), consolidated undrained (CU), and consolidated drained (CD)—depending on whether drainage is permitted and how pore water pressure is measured. Advanced triaxial systems may include automated loading frames, pressure-volume controllers, pore pressure transducers, and data acquisition systems, allowing precise control and monitoring of load, deformation, and pore water response. These systems are capable of performing both static and dynamic testing, including cyclic loading for earthquake engineering applications. Triaxial testing provides critical parameters such as shear strength, cohesion, angle of internal friction, Young’s modulus, and Poisson’s ratio, which are essential for analyzing slope stability, foundation behavior, and earth structure performance. Due to its versatility and ability to simulate real-world stress conditions, triaxial testing remains one of the most reliable and widely used methods for characterizing soil behavior in geotechnical engineering.

Soil Water Characteristic Curves (SWCC), also known as soil moisture retention curves, describe the relationship between soil water content and matric suction, providing critical insight into a soil's hydraulic behavior. These curves are essential for understanding unsaturated soil mechanics, infiltration, evaporation, and the movement of water through soil profiles. Two commonly used instruments for generating a complete SWCC are the HYPROP and the WP4C. The HYPROP system is used to measure the wet range of the curve (low suction values, typically 0–100 kPa) by monitoring the evaporation of water from a saturated soil sample in a controlled environment. It uses precision tensiometers and weight sensors to continuously record suction and water loss during drying. On the other hand, the WP4C measures the dry range of the curve (high suction values up to 300 MPa) using chilled mirror dew point technology to determine the water potential of very dry soil samples. By combining data from both devices, a complete SWCC can be developed, covering the full range of soil suction. This curve is crucial for modeling unsaturated flow, estimating permeability, and predicting plant-available water. The HYPROP and WP4C together offer a powerful, accurate, and efficient approach to characterizing soil-water relationships for agricultural, environmental, and geotechnical applications.

Large-scale lysimeters are precision instruments used to study the movement of water, solutes, and nutrients through the soil profile under natural or controlled environmental conditions. Typically constructed as large soil-filled containers or monolithic blocks (often 1–3 meters deep and wide), lysimeters allow for direct measurement of evapotranspiration, infiltration, drainage, and changes in soil water storage. These systems are often equipped with sensors for monitoring soil moisture, temperature, and tension at various depths, as well as collection systems to measure leachate and solute transport. Some advanced lysimeters also integrate weighing mechanisms to detect small changes in mass due to evapotranspiration. In geotechnical and environmental engineering, large-scale lysimeters are valuable for evaluating the hydraulic performance of soils used in covers, liners, or reclamation projects, as well as assessing contaminant migration and water balance under field-like conditions. Compared to small-scale laboratory tests, lysimeters provide more realistic data by preserving natural soil structure, root systems, and climatic interactions. While they require significant investment in terms of space, time, and maintenance, large-scale lysimeters remain one of the most accurate tools for studying unsaturated zone processes and supporting long-term water management, land-use planning, and environmental impact assessments.

Temporal Electrical Resistivity Imaging (ERI) refers to the use of Electrical Resistivity Tomography (ERT) over multiple time periods to monitor and analyze changes in subsurface conditions over time. By performing repeated ERI surveys at the same location, temporal ERI allows for the tracking of dynamic processes such as groundwater movement, contamination plumes, soil moisture changes, and the effects of construction or other site interventions. These time-lapse measurements can help identify seasonal fluctuations, the impact of rainfall, or the progression of soil consolidation or contamination spread. The ability to compare resistivity data over time makes temporal ERI a powerful tool for environmental monitoring, groundwater hydrology studies, and geotechnical applications, as it provides insights into how subsurface properties evolve in response to natural or human-induced factors. The technique is particularly useful for assessing long-term site conditions, detecting early-stage issues like leakage or instability, and providing data for risk assessment and mitigation strategies. By combining high spatial resolution with temporal monitoring, temporal ERI offers a comprehensive understanding of subsurface dynamics that is not possible with a single, static measurement.

Vertical Electrical Resistivity Imaging (VERT-ERI) is a specialized application of Electrical Resistivity Imaging (ERI) that focuses on mapping subsurface resistivity variations along a vertical profile, providing detailed information about the vertical distribution of geological layers and fluid content. Unlike traditional 2D or 3D ERI surveys that typically involve a horizontal array of electrodes, VERT-ERI involves placing electrodes in a vertical arrangement along a borehole or at specific intervals within the soil profile. This setup allows for more focused exploration of subsurface structures, particularly in layered deposits or when there is a need to analyze vertical variations in resistivity. VERT-ERI is especially useful for characterizing geotechnical conditions in areas with significant vertical heterogeneity, such as in fractured rock, soil profiles with varying moisture content, or stratified sediments. It helps identify features like groundwater tables, contamination zones, or soil compaction differences, all of which may be more apparent in the vertical direction. In environmental engineering, for example, VERT-ERI is employed to track the vertical migration of contaminants or to monitor the movement of water in confined aquifers. The technique can also be applied to assess the performance of geotechnical structures such as deep foundations, embankments, and tunnels by providing detailed data about vertical changes in subsurface resistivity over time. When combined with traditional ERI methods or other geophysical techniques, VERT-ERI can offer a complementary, highly detailed view of subsurface conditions, improving site characterization, resource management, and hazard mitigation efforts.