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Geotechnical monitoring

Heterogeneous or problematic ground conditions can cause unpredictable behaviour with devastating consequences for the construction of new infrastructure and the maintenance of existing assets. 

James Fisher Strainstall (JF Strainstall) adapts a range of solutions to provide reliable and actionable data; a powerful tool in risk reduction which provides cost savings over other alternatives.

As a leading innovator and provider of specialist structural health monitoring and testing services with more than 50 years’ experience, James Fisher Strainstall applies state-of-the-art monitoring technology to safeguard critical infrastructure against ground-borne risks. We support clients across all sectors by scoping, designing, installing, and maintaining monitoring systems to mitigate risk to their assets. Our team of experts are impartial to instrument manufacturers. We apply our knowledge to integrate any sensor type into the data acquisition system, meaning we can deliver a solution that meets any requirement. With our in-house design and production facilities, we are able to develop bespoke systems with improved capabilities over available technology.

Slope monitoring solutions

Our team designs and installs early warning systems to notify asset owners of ground movements, allowing them to take preventative actions, which can include carrying out emergency inspections, implementing temporary speed restrictions, or closing roads or railway lines. We develop systems using a range of technologies to monitor:

  • Depth of slip plane
  • Lateral movement at surface
  • Settlement and heave
  • Rainfall
  • Groundwater level and pressure
  • Load in soil nails and retaining walls
  • Tilt of surface and retaining walls

Tunnel monitoring solutions

Whether for a new tunnel construction project or an existing operational asset, instrumentation is crucial for ensuring the integrity and safety of subsurface structures.

For new projects, geotechnical ground instrumentation is used to confirm the construction against design. Measurement of ground movements during tunnel construction allows settlements to be compared to predictions and, where threshold conditions occur, action to be taken. For existing tunnels, monitoring is typically carried out to ensure the tunnel or its surrounding geological conditions are not adversely affected by nearby construction works, such as piling, adjacent construction, demolition or tunnelling.

Typical measurements taken include:

  • Ground movements or settlement
  • Settlement of above-ground or underground structures
  • Groundwater level and pressure
  • Tunnel convergence and deformation
  • Crack propagation and growth
  • Load, stress and strain in tunnel lining
  • Rate of corrosion in reinforced concrete tunnel lining
  • Load in rock bolts and soil nails

Rock fall monitoring solutions

The sudden nature of rock failure makes it difficult to monitor any precursory movement in order to anticipate pending failure. At the earliest, any movement will be detected at the moment at which the rock fails, possibly obstructing a road or railway. In these cases, time is of the essence and any early warning systems must allow data to be processed and transmitted in real time as signallers, or highways agency control rooms will need to respond within seconds of any incident occurring. 

We have designed systems to provide an early warning to alert customers when at-risk rock slopes or cliff faces fail. These systems utilise load sensors within the rock fall’s mesh and netting. They are linked to the appropriate network rail signalling centre or highways control room to alert them when rock falls have occurred, allowing immediate and appropriate action to be taken. This allows temporary speed restrictions or line and lane closures to be implemented only when there is a measurable risk to traffic, as opposed to blanket restrictions.

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