Geotechnics and geology

The services offered by CODEXSA within this discipline are quite broad and perfectly adaptable to our clients' needs. They have been developed since we started as a company 30 years ago. During this time, we have conducted over 10,000 geological-geotechnical studies. This affords us vast experience and thorough knowledge of soil. Of note are the following activities applicable to any market segment that requires them.



This section lists a wide number of onsite tests conducted via company equipment and own specialist personnel.
GEOREFERENCING RECOGNITION POINTS AND GEOLOGICAL CARTOGRAPHY

CODEXSA has GNSS/GIS hand receivers to georeference points in the field. These units provide constant submetric readings in real time and post processing. They combine high-performance receivers with hand units in order to take accurate and reliable data, even in the most demanding environments.

These instruments are also used as support in making geological cartography. They make it possible to perform geological surveys at proper scales by using topographical base maps, aerial photos and satellite images. Finally, they are complemented with geological-geotechnical profiles.

MECHANICAL BORING

We have specialized, versatile equipment to perform mechanical boring that makes it possible to directly observe the materials that comprise the subsoil. Unaltered samples or paraffin-coated specimens are taken from which the necessary parameters for studying the land's behavior will be obtained in the laboratory.

We have the capacity to develop different operations that offer suitable solutions for each type of land and project:

  • Soil drilling.
  • Gravel drilling.
  • Rock drilling.
  • Rotation sample taking: simple battery.
  • Rotation sample taking: double battery.
  • Rotation sample taking: triple battery.
  • Rotation sample taking triple battery; thin wall.
  • Unaltered sample taking: Shelby.
  • Unaltered sample taking: fixed piston.
  • Thick wall sample taking.
  • SPT Test.
  • Paraffin-coated specimen.
  • Permeability: Lugeon test.
  • Permeability: Lefranc test.
  • Pressure meter test (OYO pressure meters).
  • Installation of inclinometers.
  • Inclinometer measurement reading.
  • Piezometer installation and drainage.
  • Vane Test, pocket penetrometer.
  • Checking resistance at pile tip.
WIRE-LINE SYSTEM DRILLING

For developing deep drilling, we have equipment designed to use the wire-line technique. Its main feature is that maneuvers to hoist the rods to empty the tube specimen are avoided. This makes it possible to reduce operation times.

DYNAMIC PROBING TESTS

They constitute the simplest way to determine the resistance of the different layers or strata of land by driving in a probing component joined to the rods.

Our equipment is known for being self-propelled with small dimensions. This makes it easy to use it in areas with difficult access. It makes it possible to perform different types of probing tests:

  • Borros.
  • DPH (Dynamic Probing Heavy).
  • DPSH (Dynamic Probing Super Heavy).
TEST PITS

As a supplement to complex campaigns or in the case of simple surveying, we conduct test pits that enable direct soil inspection, sample taking and conducting onsite tests. Test pits are directed and described by a geologist. A stratigraphic cut of the land is attached as well as its condition with regard to humidity, hardness or compactness.

INCLINOMETERS: INSTRUMENTS, RECORDING MEASUREMENTS AND INTERPRETATION

We have the technical resources and training both for land or component instrumentation and for taking subsequent measurements. We also have specific software to obtain graphics from deflections accumulated during probing and their evolution over time. This technique is particularly useful and recommendable in studying the stability of hillsides and slopes because it makes it possible to identify the direction and magnitude of the movements produced.

PRESSURE METER TESTS

CODEXSA has a mobile unit to perform pressure meter tests: Onsite deformation of soils and soft rocks.

These tests require previous drilling to reach the stratum upon which work is to be done. We solve this matter with our own drilling equipment. Uniform radial pressure is applied on the geotechnical level wall. This pressure is progressively increased with a certain speed and an ongoing reading is taken.

VIBRATING CORD PIEZOMETERS: INSTALATION, READING MEASUREMENTS AND INTERPRETATION

With this technique, we can obtain values for water pressure from pores as well as the water level in drillings, embankments, etc. To do so, the values of the detectedvibrations are electronically translated in order to monitor piezometric values of water in soils and rocks. The range of measurements that the installed piezometers offer is generally 350 KPa.

We have a portable reading unit with a capacity for more than 11,000 readings and scaled to allow direct conversion to engineering units.

ELECTRICAL GEOPHYSICS

We have these geophysical recognition techniques in order to support and supplement the geological-geotechnical and hydrogeological campaigns, especially on very broad surfaces that are based on properties such as electricity conductors of the land different strata.

  • Electrical resistivity: It is used to determine conductive and chemical aggressiveness characteristics of subsoil materials at certain depths.
  • Vertical Electrical Probes: They make it possible to identify the type of land existing in the subsoil, the strata present and their thicknesses.
  • Test pits or geoelectrical tomographies: They make it possible to obtain a continuous geoelectrical section of the land.
PUMPING AND TRACER TESTS IN AQUIFERS

As a supplement to the geotechnical tests, we offer gaging and pumping tests in aquifers.

On the one hand, the aquifer's parameters are determined (hydraulic conductivity, transmissivity and storage coefficient) are determined. The behavior during pumping is also determined in order to determine the flow direction with the help of tracers.

And on the other hand, the aquifer's hydraulic properties are determined in order to subsequently predict their behavior under diverse situations, evaluate the availability of underground water resources, etc.

VERIFICATION AND INJECTION AT PILE TIPS

We offer our clients this method of directly auscultating pile tip concrete. It also makes it possible to become familiar with the characteristics of the land that serve as support. In those cases where it is necessary, we can perform injection via pumping a cement grout that improves the pile tip's supportive characteristics.

CODEXSA experience doing this work at sites on land and sea.

The experience acquired over the span of 30 years allows us to provide our clients with advanced solutions that are adapted to their needs. This is the framework for the advice or geotechnical assistance that we provide at different levels based on the characteristics of the project. We can participate in either one or several of the following stages:

  • Geotechnics campaign design.
  • Onsite tracking of geotechnical field campaigns.
  • Excavation supervision. Verification of project geotechnical parameters.
  • Advising and optimization of excavation and foundation solutions.
  • Foundation design calculations and recommendations.
  • Geological-Geotechnical Extensions.

This work is carried out by specialized and experienced technicians able to work on projects nationwide and abroad.

Our network of laboratories allows us to conduct a vast number of specific tests in this discipline:

Soil classification.
Granulometric analysis.
Granulometric analysis by sedimentation.
Atterberg Limits.
Apparent density. Hydrostatic balance.
Real specific weight of a plot of land.
Humidity via oven drying.
Simple compression.
Direct cut (CD, CU, UU). (*)
Resistance of soil. Triaxial. (CD,CU,UU.) (*)
Permeability with pressure on glue on triaxial cell.
Swelling pressure on edometer. (*)
Free swelling in edometer. (*)
Consolidation in edometer. (*)
Collapse test. (*)
Lambe expansivity.
Flooding under load in edometer. (*)
Variable load permeability.
Constant load permeability.
Porosity of a plot of land.
Determination of pH.
Baumann-Gully Acidity.
Soluble sulfates.
Carbonate content. Bernard Calcimeter.
Aggressiveness of phreatic water.
Organic matter content.
Content of chloride, sulfates, etc.
Proctor Test (normal/modified).
C.B.R.

(*) CODEXSA® has 23 edometers, 5 direct cutting machines and 1 triaxial unit, all computerized, as well as a consolidation bedplate with 6 cells.

Our technicians can devise different types of reports that adapt to our clients and specific needs of their projects.

GEOTECHNICAL STUDIES

Taken from field and laboratory campaigns, the reports offer suitable recommendations on the most appropriate foundation for the project in question and based on the specific geotechnical and geological characteristics of the land. The different possible alternatives are stated with the recommendations to consider in each case. Geotechnical reports are accompanied by compilation of data, results and calculations that justify all the conclusions and solutions reached.

HYDROGEOLOGICAL AND HYDROLOGICAL STUDIES

Hydrogeological studies are based on determining and characterizing capacities such as the materials' aquifers, both in solid rock (based on fracturing analysis) and in sedimentary materials (porosity, texture and structure). Once the aquifer and behavior of the material have been characterized, it will be possible to know their regulation and hydrological and hydrogeological operation.

Moreover, we conduct natural risk studies, namely hydraulic studies, to determine flooding risks; a frequent occurrence in the Mediterranean climate.

The tests and studies conducted make it possible to characterize the aquifer's hydrogeological-hydraulic properties (permeability, hydraulic conductivity, transmissivity and storage coefficient) in order to subsequently predict its behavior under diverse situations, and to evaluate the availability of underground water, etc.

Hydrogeological studies:

Characterization of aquifers (permeability, flows, storage and quality of water).
Capturing underground water for storage (well design study and project).
Influence of phreatic levels and volumes for foundations and infrastructures.
Studies for protecting and determining pollution.
Pumping and tracer tests in aquifers.

Hidrological studies:

Characterization of hydrographic basins (water balances). Water resource analysis.
Flood study.
Estudio de inundaciones y avenidas máximas.
Determining Hydraulic Public Domain (HPD).
Drainage network design (rainwater).
Wastewater treatment plan design and projects.
SLOPE STABILITY

Through the use of specific software and the data obtained in the corresponding field and laboratory campaigns, simulations will be conducted to establish proper stability and safety parameters.

Thus, it will be possible to prevent possible landslides while work is being performed. It will also make it possible to size up containing walls and causes of possible pathologies, etc. can be established.

RESULTS REPORT

We devise compiled reports of the field and laboratory campaigns that state the results obtained, characteristics of the materials tested, stratigraphic cuts and photographs. Thus, all necessary parameters for the most recommendable design will be available.

ENVIRONMENTAL CHARACTERIZATION STUDIES

The purpose of environmental characterization of soil and underground water is to either confirm or rule out the resence of contaminants in the subsoil by performing fieldwork and identifying the potential sources of contamination. This makes it possible to evaluate the possibility that significant contamination has occurred at the site where future projects will be located.

The parameters that are regularly studied are:

  • On soil samples:
    • pH.
    • Conductivity.
    • Organic matter content.
    • Granulometry and texture.
    • TPH (Total Hydrocarbons).
    • Metals Scan (As, Cu, Cr, Co, Cd, Ni, Pb, Hg and Zn).
    • PCB´s (Polychlorinated biphenyls).
  • On underground water samples:
    • pH
    • Conductivity
    • Temperature.
    • Dissolved oxygen.
    • COD (Chemical Oxygen Demand)
    • TPH (Total Hydrocarbons).
    • Metals Scan (As, Cu, Cr, Co, Cd, Ni, Pb, Hg and Zn).
    • PCB´s (Polychlorinated biphenyls).

To conduct this type of study, the following aspects have special relevance:

  • Procurement of remarkable regional information.
  • Selected sampling points according to the study area's characteristics.
  • Sampling at intervals of marked depth.
  • Proper packaging of samples (with volatile material loss control).
  • Proper sampling of underground water (draining probes).
  • Tracking via chains of custody and packaging procedures and conservation of samples according to international standards.