Underground Works

Underground works that take place in an urban environment pose specific difficulties due to their impact on nearby buildings and structures.

Monitoring is a safety tool in the construction of tunnels, for both the structures built and for those in the immediate surroundings. The Monitoring Plan manages this tool, and it is essential that experts in the field perform all its aspects so that it is given due importance and a complete chain of measurement and analysis is devised.

In this respect, Ofiteco has the experience and resources to provide a compact, reliable and comprehensive solution for any project.

The Monitoring Plan covers all project control aspects from design phases to implementation on site, supervision and information management.

The initial phases in drafting the Monitoring Plan are:

• Study of project documentation: alignment, construction method, geotechnics, etc.
• Producing a Prior Inventory of Buildings in the field, classifying them according to how vulnerable they are and the estimated impact of the construction project.
• Selection of control variables and appropriate instrumentation for monitoring them.
• Selection of the type of reading to be performed: manual or automated for each variable to be controlled.
• Zoning of the alignment based on hazardousness and instrumentation distribution.
• Installation and reading procedures.
• Definition of Control Thresholds for each specific control.
• Establishment of Reading Frequency for every manual reading control variable.
• Establishment of the flow of information and Action Protocol in the event that Control Thresholds are exceeded.

Equipment selection and installation: this is an essential stage in the measurement chain and it is therefore important that it is performed and supervised by the team that will later take the measurements and analyse the data. Installation procedures will be in place before any equipment is installed. Ofiteco has over 40 years experience in the installation of instrumentation equipment.

Supervision: when the Control Thresholds established for manual reading devices are exceeded, the Monitoring Plan states the frequency of the reading for each of them. Procedures will be followed to take the initial measurement and the periodic readings established in the Monitoring Plan, as well as the periodic calibrations of the measurement instruments to be performed on site.

Maintenance: the monitoring teams on site will be responsible for the maintenance and replacement of devices, which may become damaged during the execution of the works.

Specific controls of the surrounding area of the site, such as vibration control and environmental factors (dust, noise), etc.

Information analysis: the employee with maximum responsibility for the analysis of the obtained data is the Monitoring Manager, whose duties include: producing the Monitoring Plan, producing the installation and reading procedures, coordination of work teams, analysis and filtering of the obtained data and writing of result reports.

The main agents in the project, namely Project Management, Designers, Technical Assistance and Construction Company, are provided with a Web Management Tool for the storage, management and display of data, which can convert the huge quantity of data generated during the monitoring into a useful tool.

The web tools functionalities include:

• Real time of automatically acquired data (e.g. Total Stations).
• Manually read data.
• Display of engineering values.
• Possibility of historic display of individual variables or sets of variables.
• Alarm and warning management.
• Inclusion of TBM progress variables, advance end progress in conventional methods, diaphragm walls, etc.
• Generating reports and exporting data.
• Access using a password-protected browser.