24/7 asset monitoring assures Rotterdamsebaan tunnel construction

Challenge

The new 4 km-long Rotterdamsebaan will connect the A4-A13 motorway to The Hague’s inner ring road. With almost half in the form of tunnelling beneath residential and industrial areas, the Municipality of The Hague set challenging requirements for the monitoring and control of tunnel boring machine (TBM) operations.

Solution

To reduce geotechnical risks and guarantee the integrity of assets above and adjacent to the designed tunnel line, we implemented a comprehensive 24/7 geo-monitoring programme. Harnessing asset and soil data from millions of data points, our dynamic Virgeo® data management platform offered near-real-time reporting in unprecedented detail, readily meeting the client’s rigorous risk management demands.

The new dual carriageway included an underground section 1860 m long that comprised two bored tunnels, each with an internal diameter of 10.15 m.

With the TBM operating at the relatively shallow depths of between 8 m and 31 m, intensive monitoring was a priority to measure the effects of soil relaxation in response to the passage of the TBM shield. Structural risks, such as rotation, sagging and hogging, are associated with the possible differential settlement of nearby built structures, depending on their relative distance, foundations and ground conditions.

Complex monitoring campaign

To achieve the data magnitude and detail critical for effective TBM risk management, we designed and implemented an extensive monitoring programme involving:

• 40 robotic total stations (RTSs) with automatic levelling and 6000 prisms

• Geodetic control measurements including relative and absolute x, y and z values in millimetres

• 24/7 asset and surface monitoring with data collection from an estimated 200 million data points

Fast-track data-process and visualisation

Our Virgeo® georisk platform, with its ability to rapidly process and analyse huge volumes of Geo-data into usable intelligence, provided:

• Near-real-time insight of all subsurface data

• Live positioning of the TBM

• Metadata for all monitoring assets

• Processing of more than 400,000 measurements per day into an easy-to-use format

Our insights gave the client a continuous flow of extremely reliable information for enhanced control of ground risks and tunnelling operations.

Real-time visualisation of the status of monitoring points, using easy reference colour-coding, provided the project team with constant clarity on the status of the nearby buildings and surface settlement. Outlier detection contributed to a substantial reduction in unwanted notifications, and cloud-computing reduced latency, ensuring excellent speed of response to users even when accessing large datasets.

The digital platform’s uptime was well over 99 %, adding significant value for the client and demonstrating the platform’s robustness for greater risk control

Innovative highlight

Innovative georisk modelling and digital sharing improved technical and safety control during construction, and Virgeo® met the client’s and stakeholders’ strict criteria for TBM impact monitoring and data reporting.

Online availability of near-real-time data on the tunnelling environment gave both client and contractor unprecedented project insight. This supported fully informed and proactive decision-making for the construction team, while offering important transparency for public reassurance that the project progress remained within the safety thresholds.

Impact

With over 300 assets, including businesses and housing, located above or adjacent to the tunnel corridor, we met the objective of delivering continuous insight into actual settlement. Our extensive monitoring and fast-tracking of highly accurate data using Virgeo® gave the project team powerful ground knowledge for improved control and risk management of TBM activities.

This enabled boring operations to be optimised to reduce surface ground settlements and to control and mitigate against the risk of damage to adjacent assets. Just as critical, our versatile digital solution engendered public confidence by demonstrating that the client and project team had a high degree of control during construction.