Construction Monitoring

Work close to an operating railway, a metro tunnel, a highway or a buried utility is carried out under the asset owner’s conditions. Those conditions set exclusion zones, predicted movement limits and reporting obligations, and they are enforced.

DYWIDAG designs and operates the monitoring that those obligations. Movement of the third-party asset is measured independently of the works, against the limits written into the agreement, and reported in the form and at the frequency the owner requires. Track geometry, tunnel convergence, structural movement of bridges and retaining structures, ground settlement above and alongside the asset, and vibration from piling, excavation and demolition are all covered.

Instrumentation is selected for assets that cannot be taken out of service and for locations with no power or communications: wireless tilt sensors, automated total stations, in-place inclinometers, vibrating wire piezometers, crack gauges and vibration meters, reporting through gateways to Infrastructure Intelligence.

• Independent measurement of railways, tunnels, highways, bridges and buried utilities against the limits in the asset protection agreement
• Reporting in the form and at the frequency the asset owner requires, with alarms escalating under the agreed protocol

A deep excavation could be supported by a system that is temporary by design: sheet pile or diaphragm walls, props, ground anchors, berms and falsework, each carrying load that changes as the dig advances and as the permanent works take over. Deflection and load have to be measured against the design assumptions at every stage.

DYWIDAG monitors the support system through the full construction sequence. Wall deflection is measured by in-place inclinometers within the wall and by automated total station observation of wall-mounted prisms. Prop loads and ground anchor loads are read by load cells and strain gauges, so that structures are not subjected to excessive stresses beyond their design capacities. Crane bases, retained facades and falsework are instrumented with tilt sensors and optical displacement sensors where their stability governs the programme.

Monitoring is staged to follow the construction sequence, with instruments installed, relocated and removed as the works advance, keeping equipment on site only where it is needed.

• Wall deflection by in-place inclinometers and automated total station, with prop and ground anchor loads read against design capacities
• Crane bases, retained facades and falsework instrumented, with monitoring staged to follow the construction sequence

Excavation, piling, tunnelling and dewatering can all redistribute stress and water in the ground, and the surface expression of that is settlement or heave, including some distance from the activity causing it. The mechanism is subsurface, and the movement reaches neighbouring structures before anything is visible at ground level.

DYWIDAG assesses soil and rock stability by measuring ground inclination, pore water pressure and ground deformation, detecting movements and ensuring safety and stability. Measurement is taken within the borehole by in-place inclinometers reporting automatically at a configured interval, and by manual probe survey where verification is required or where power and communications are impractical. Piezometers record pore water pressure and groundwater level, which commonly explains the movement observed, and extensometers and settlement cells quantify vertical movement at depth and at the surface.

• Weather is recorded alongside the ground data, because wind, rainfall and temperature are frequently external contributing factors behind the movement.
• Settlement and heave quantified by extensometers and settlement cells, with rainfall, wind and temperature recorded as context.
• Ground inclination, pore water pressure and deformation, with in-place inclinometers reporting automatically and manual probe surveys in the same borehole

Consent to build is frequently conditional on what the site emits. Noise, dust and vibration limits are written into planning conditions and local consents, and a complaint from a neighbour or a claim of damage from an adjoining owner is answered with measurement records or it is not answered at all.

DYWIDAG provides assessment and management of noise, dust and vibration levels, to mitigate potential impacts on surrounding communities and ecosystems. Continuous monitors are positioned at the site boundary and at sensitive receptors, recording against the limits set in the consent. Vibration is measured by triaxial meters that detect a threshold breach at the sensor itself, which matters during piling, demolition, breaking and compaction, when levels change within seconds.

Measurement runs continuously, so the record covers the whole period of the works and not only the occasions someone attended. Readings and alarms are held in Infrastructure Intelligence with automated notification by email or SMS.

• Noise, dust and vibration measured continuously at the boundary and at sensitive receptors, against the limits set in the consent
• Triaxial vibration meters detecting threshold breaches at the sensor during piling, demolition, breaking and compaction