Where every geotechnical project begins: getting to know the ground in place, measuring it and recording it.
Drilling and field testing are data-gathering works that form the basis of every geotechnical project, enabling the actual ground conditions to be determined in place.
With its experienced staff and advanced equipment fleet, Geobim Engineering carries out drilling works at the depth and precision the project requires; it sets out the soil profile, layer transitions and groundwater level in detail. As part of our field works, the bearing capacity, compressibility, consistency and permeability of the ground are determined through tests compliant with international standards such as SPT, CPT/CPTu and pressuremeter.
The disturbed and undisturbed samples taken from the boreholes are carefully preserved for the analyses to be carried out in the laboratory. All field works are conducted in full compliance with the relevant standards and regulations; the data obtained is systematically recorded so as to form a sound engineering basis for the subsequent design and execution stages.
Our ground investigation methods, each compliant with international standards, applied individually or together depending on the project.
01
The most common in-situ soil test, measuring the number of blows (N) required for a 30 cm penetration of a standard sampler driven by a 63.5 kg hammer inside a borehole.
02
A high-resolution in-situ ground investigation system that continuously records the tip resistance, friction and (in CPTu) pore water pressure of an electronic cone pushed into the ground at a constant rate.
03
A direct test in which a cylindrical probe lowered into the borehole is inflated to load the surrounding ground horizontally, yielding the in-situ horizontal deformation modulus (EM) and limit pressure (PL).
04
The horizontal deformation profile is taken at regular intervals from inclinometer casings installed in the ground or in structural elements. It is a critical early-warning tool in monitoring deep excavations, shoring walls and slopes; it provides lateral movement tracking with millimetric precision.
05
A test that directly measures the bearing capacity and load-settlement behavior of a pile in the field; performed by static, dynamic or bi-directional (Osterberg) methods.
06
A test that rapidly and non-destructively evaluates the integrity of a pile (crack, necking, neck-down, length) by measuring the reflections of the stress wave propagating along the pile from a low-strain hammer blow.
The Standard Penetration Test (SPT) is the most widely used in-situ ground investigation method worldwide. The test consists of driving a standard split-spoon sampler lowered to the bottom of the borehole to a depth of 45 cm by the free fall of a 63.5 kg hammer over 76 cm, and recording the number of blows (N) required for the final 30 cm.
The resulting N value allows the relative density, internal friction angle, bearing capacity and compressibility of the ground to be determined directly or through correlations. It also provides a key input parameter for liquefaction analysis under seismic action. The disturbed samples taken simultaneously with the test are evaluated for soil classification and laboratory tests.
In SPT applications, Geobim Engineering measures the hammer energy efficiency (Er) with calibrated equipment in compliance with standards; it presents the N values in (N₁)₆₀ format with energy, fines and overburden corrections, producing accurate and reliable design parameters.
ASTM D1586 · TS 1900-1| Parameter | Value / Description |
|---|---|
| Hammer mass | 63,5 kg |
| Drop height | 76 cm free fall |
| Sampler | Split-spoon, Ø 50.8 mm / Ø 34.9 mm inner diameter |
| N value | Number of blows for the final 30 cm (blows/30 cm) |
| Measured quantities | Penetration resistance, soil class (sample) |
| Applicable soil | Granular soils, clays, transition layers |
The Cone Penetration Test (CPT) is an advanced in-situ investigation method that continuously records the tip resistance (qc) and sleeve friction (fs) with depth as an electronic probe with a 60° conical tip is pushed into the ground at a constant rate of 2 cm/s. The CPTu version, also known as the piezocone, additionally records the pore water pressure at the u₂ position in real time; this also provides information about the consolidation and drainage conditions and the in-situ stress history.
CPT/CPTu is used to determine soil stratification continuously and at high resolution, to detect thin layers and for soil classification with established correlations such as Robertson (1990). Compared with the SPT, its operator dependence is far lower and its repeatability is high; for this reason it is the primary investigation tool preferred on critical projects.
In CPT/CPTu applications, Geobim Engineering uses an electronic piezocone system; by recording all data in real time, it accurately reports the soil profile, bearing capacity parameters and liquefaction risk.
ASTM D3441 · ASTM D5778 · ISO 22476-1| Parameter | Value / Description |
|---|---|
| Push rate | 2.0 cm/s (constant) |
| Cone angle | 60° · Base area 10 cm² |
| qc — Tip resistance | Axial force on the cone tip / area |
| fs — Sleeve friction | Unit area force on the friction sleeve |
| u₂ (CPTu) | Pore water pressure at the cone shoulder |
| Data resolution | Continuous recording every 1–2 cm of depth |
The pressuremeter test (PMT) is based on inflating the measuring cell in the body of a cylindrical probe lowered into the borehole with water or gas pressure to load the surrounding ground horizontally. From the pressuremeter curve obtained by measuring the applied pressure and the ground deformation simultaneously, the in-situ horizontal deformation modulus (EM), limit pressure (PL) and subgrade reaction coefficient (Ks) are determined directly.
Unlike penetration tests such as SPT or CPT, the pressuremeter test applies load horizontally to the ground, simulating the real in-situ stress conditions. Thanks to this feature, it is particularly valuable in the design of retaining and shoring walls, in load-settlement analyses and in determining the lateral capacity of piles. It is applicable across a wide range of soils such as clay, silt, sand, gravel and soft rock.
With Ménard-type pressuremeter equipment, Geobim Engineering applies both pre-bored and self-boring procedures to produce repeatable results that cause minimal disturbance to the ground and are fully compliant with standards.
ASTM D4719 · NF P 94-110 · ISO 22476-4| Parameter | Value / Description |
|---|---|
| EM — Deformation modulus | From the linear region of the loading curve |
| PL — Limit pressure | The pressure at which ground yielding begins |
| P₀ — Horizontal earth pressure | In-situ horizontal stress estimate |
| Probe diameter | Ø 44–74 mm (depending on borehole diameter) |
| Application depth | ≤ 60 m |
| Applicable soil | Clay, silt, sand, gravel, soft rock |
The inclinometer is based on measuring horizontal displacement along depth by means of a probe lowered into special grooved casings installed vertically in the ground or in structural elements (shoring wall, retaining wall, embankment, landslide mass). Readings taken at set intervals reveal the cumulative lateral deformation profile with millimetric precision.
It is a critical early-warning tool for monitoring the development of deformation over time in deep excavation shoring systems, slopes, retaining structures, embankments and landslide areas. It provides reliable data so that timely measures can be taken if threshold values are exceeded.
Geobim Engineering ensures the correct installation of inclinometer casings and performs periodic or continuous readings with a calibrated probe; it evaluates the data against the reference (zero) reading and reports it in terms of direction and magnitude.
ASTM D6230 · ISO 18674-3| Parameter | Value / Description |
|---|---|
| Measured quantity | Horizontal displacement with depth |
| Reading interval | Typically every 0.5 m of depth |
| Monitoring type | Periodic or continuous |
| Application area | Shoring, slope, retaining, embankment, landslide |
The pile load test is the most reliable method for determining the actual behavior of a pile under axial (compression/tension) or lateral load in the field. Load is applied to the pile in increments and the settlement/displacement occurring at each increment is measured to obtain the load-settlement curve; from this curve the ultimate bearing capacity and the safe working load are determined.
The static load test (ASTM D1143) is the reference method and is performed using reaction piles or kentledge. Dynamic loading (high strain, ASTM D4945) offers a fast and economical alternative, while the bi-directional load cell (Osterberg) method is preferred for high-capacity piles. Lateral load tests, in turn, are essential in the design of piles subjected to horizontal forces.
Geobim Engineering designs the test setup according to the pile type and target load; it records load, settlement and, when required, strain data along the pile with precise instrumentation, thereby verifying the design capacity.
ASTM D1143 · ASTM D4945 · ASTM D3966| Parameter | Value / Description |
|---|---|
| Measured quantity | Load-settlement / displacement relationship |
| Methods | Static, dynamic, Osterberg, lateral |
| Maximum load | ≥ 1.5–2.0 times the design load |
| Result | Ultimate capacity and safe working load |
The Pile Integrity Test (PIT — Pile Integrity Test) is based on the principle of recording, with an accelerometer, the reflection of a low-strain stress wave that is generated by a small hand-held hammer blow on the pile head and travels along the pile, reflecting from changes in section or impedance (crack, necking, widening, pile toe).
Since it is a fast, economical and non-destructive (NDT) method, it is ideal for screening the integrity of a large number of piles on a site in a short time. It is used to verify the pile length and to detect the approximate location of concrete discontinuities and potential defects; suspicious results are verified, when required, by methods such as sonic tomography (CSL).
Geobim Engineering performs PIT measurements with calibrated equipment; it evaluates the wave reflections in the time domain and reports the continuity condition for each pile.
ASTM D5882 · ASTM D6760| Parameter | Value / Description |
|---|---|
| Method | Low-strain hammer blow (sonic echo) |
| Measured quantity | Stress wave reflection time / velocity |
| Detected | Crack, necking, widening, pile length |
| Advantage | Fast, economical, non-destructive (NDT) |
Complementary methods applied together with or independently of SPT, CPT and PMT depending on the project.
A test that measures the undrained shear strength (Cu) of soft cohesive soils in place. Cu is obtained directly from the shear moment generated by rotating a four-bladed vane; it is critically important in very soft clays where sampling and laboratory procedures are problematic.
The settlement-load relationship is measured by applying incremental load to a rigid steel plate placed on site. The bearing capacity and deformation modulus are determined in place for shallow and semi-deep foundations; it is widely used in checking fills, foundation bases and road subgrades.
The hydraulic conductivity (k) of soil and rock is measured on site using the Lefranc (open-end), Lugeon (packer) and slug test methods. It provides a key input parameter in planning ground improvement, drainage design, water-retaining structures and grouting programmes.
Continuous core samples are taken from soil and rock by the rotary drilling method. The Rock Quality Designation (RQD), layer transitions and fracture frequency are determined. Undisturbed samples are sent to the laboratory for consolidation, triaxial and permeability tests.
The groundwater level and water pressure are measured periodically or continuously with piezometers installed in boreholes. The water conditions critical to excavation design, drainage planning and shoring calculations are monitored and recorded before and throughout construction.
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