Geo-technical Instrumentation

Geo-technical monitoring has become a major requirement in all aspects of today’s construction industry.

Requirements for instrumentation that can be used in the continuous monitoring of embankments, structural settlement , load and stress testing, means clients are now looking for reliable instrumentation that is proven in today’s harsh working environments.

NVM have a proven record in the supply, installation and training of the following geo – technical instrumentation.

Inclinometer systems

Inclinometer systems can be used to measure deflections in piles and to ensure that holding anchors put in place are performing within their tolerances, and are not affected by ground movements.  In this way they can be of assistance to design teams by confirming that projects are working with in the agreed limits put in place prior to construction.  Inclinometer systems are used in the monitoring of piling operations to detect slope zones of movement or displacement and to establish if the movement is constant, accelerated or responding to any remedial measures put in place by the contractor.

The main objective of measuring inclination is to predict any type of movement so that preventative measures can be undertaken and the project can move forward with out any safety or build concern.

 

Applications for vertical inclinometers include:

• Monitoring slopes and landslides to detect zones of movement and establish whether movement is constant, accelerating, or responding to remedial measures.
• Monitoring dams, dam abutments, and upstream slopes for movement during and after impoundment.
• Monitoring the effects of tunneling operations to ensure that adjacent structures are not damaged by ground movements.

Embankment monitoring

The construction of motorway or rail embankments and levees often require instrumentation to monitor the progress of consolidation and to determine whether the embankment is stable or if there is movement that it is within agreed design tolerances.

Geo-technical Instrumentation can also be utilized to monitor the effectiveness of vertical drains used to accelerate consolidation in embankment construction or on any project where the risk of slope destabilisation is evident.

Typical Instruments used to measure Embankment Movement include:

Inclinometers, Piezometers, Pressure Cells, Settlement Systems, Rod Extensometers

All the above can be recorded both manually or automatically depending on the site requirements.

A system could consist of piezometers installed on the upper slopes of the embankment, tiltmeters placed on retaining walls, and inclinometers which are installed through the slip plane. The piezometers monitor pore-water pressure, the tiltmeters monitor rotation of the retaining walls, and the inclinometers monitor subsurface movements.

Piezometers

There are numerous applications for piezometers and thus there are many different types of piezometers – (standpipe, pneumatic and vibrating wire) all are used to measure pore water pressure to establish safe rates of fill or excavation.

Typical applications for piezometers include the following

• Monitoring pore water pressures to evaluate slope stability.
• Monitoring dewatering systems used for excavations.
• Monitoring ground improvement systems, such as vertical drains and sand drains.
• Monitoring pore pressures to check the performance of earthfill dams and embankments.
• Monitoring pore pressures to check containment systems at landfills and tailings

Data loggers

Data loggers are an electronic devices that record data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors.  They are based on the principle of a digital processor (or computer) and are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors.  They can be used to interface with a personal computer and utilize software to activate the data logger and view and analyze the collected data, while others have a local interface device (keypad, LCD) and can be used as a stand-alone device.

One of the primary benefits of using data loggers is the ability to automatically collect data on a 24-hour basis.  Upon activation, data loggers are typically deployed and left unattended to measure and record information for the duration of the monitoring period. This allows for a comprehensive, accurate picture of the environmental conditions being monitored, such as air temperature and relative humidity.

Distribution

In 2009 NVM Ltd acquired the sole Irish distribution of Geosense Instrumentation allowing them to provide their clients with state of the art monitoring instrumentation and an in-depth bank / library of geo-technical instrumentation knowledge from one of the worlds leading instrumentation suppliers. Download the latest Geo-Sense catalogue.

Training

NVM / Geosense can provide in house training courses both in our offices in Drogheda or at our clients premises, alternatively training courses can be completed in the Geosense head office in the Uk.  These training sessions can provide clients with a basic knowledge on instrumentation allowing the client to be in command of the instrumentation in use on site while being safe in the knowledge that backup is at hand at the end of the phone through NVM.

Settlement cells

Settlement cells are used to monitor settlement and heave in soils.

 

Typical applications include:

• Monitoring settlement or heave in embankments and embankment foundations.
• Monitoring subsidence due to tunneling and mining.
• Monitoring consolidation under storage tanks.
• Monitoring settlement due to dewatering or preloading.
• Monitoring settlement in fills.

Tilt meters are used to monitor changes in the tilt of a structure.  Tilt changes may be caused construction activities, such as excavation, tunneling, and dewatering, that affect the ground that supports the structure.  Changes in tilt may also result from loading of a structure, such as the loading of a dam during impoundment, the loading of a diaphragm wall during excavation, or the loading of a bridge deck due to wind and traffic.

Tilt

Typical applications for tilt meters include:

• Monitoring stabilization measures, such as pressure grouting and underpinning.
• Monitoring structures for the effects of tunneling and excavating.
• Evaluating the performance of bridges, beams, and dams under load.
• Monitoring the stability of structures in landslide areas.
• Monitoring the deflection and deformation of retaining walls.
• Monitoring convergence and other movements in tunnels.
• Providing early warning of threatening deformations, allowing time for corrective action to be taken or, if necessary, for safe evacuation of the area.