Purpose: This application note explains how to assess the functionality and stability of retaining walls with Resensys Wireless High-Resolution Tilt/Inclination SenSpot^TM Sensors.

‍Motivation: Failure of retaining walls can cause of death of highway users. Also, failure of these walls can cause of the repair or retrofit works that can lead to delays and huge financial loss due to closures of highway lanes. Wireless structural monitoring can help to assess the condition of retaining walls to ensure the proper performance of these structures, especially in the presence of adverse environmental conditions.

Resensys Solution: Retaining walls are conventionally monitored via visual inspection and surveys. This solution is very expensive and it cannot provide accurate information about the health of retaining walls or the condition of retaining wall faces. Wireless high-resolution tilt SenSpot^TM sensors have been designed to assist authorities with this application. Wireless high-resolution Tilt SenSpot^TM sensors are able to be installed on and within retaining walls, and they are capable of monitoring inclination of retaining walls in high precision (0.00016 degree or 0.5 arcseconds). This allows complete condition awareness and remote monitoring of retaining walls, and is particularly useful to allow quick assessment of conditions after events like severe floods.

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Resensys Wireless TiltSenSpot^TM sensor for measuring and monitoring tilt/inclination (in two directions) and temperature on the face of a Retaining Wall

The Resensys cutting-edge wireless technology and tools provides cost-effective solutions to meet any requirements of the retaining walls monitoring by following benefits and unique features:

· Wireless Tilt SenSpot™ Sensor: No wiring, minimal lane closure for installation.
· Sensors with 10+ Years of Battery Life: No need for battery replacement, maintenance or calibration in the field.
· Easy Installation: Self-adhesive(e.g. on steel) or flange-mount(e.g. on concrete).
· Quick Testing: Can be installed for short-term testing, easy to remove and reuse on other structures and                                     applications.
· Long-term monitoring: Designed to be used for long-term monitoring (e.g., several years).
· Small Size and Lightweight
· Being Suitable for Different Kinds of Materials: Can be used on steel, concrete, timber and composites.
· Rugged and Weatherproof Devices:  Can operate in rain snow, ice, high humidity and extreme weather (-40°C                                                                               to +65°C or -40°F to +150°F).
· Infrastructure Less: Battery Operated, Energy self-sufficient, No need for communication infrastructure at the                                            bridge or retaining wall site.
· Provide Data Visualization and Data Analysis
· Provide Alert Services: Alert generation and management with customizable alert levels, automated structural                                                     diagnostics, capability of providing e-mail or text message alerts.
 · Very High Resolution for Wireless Tilt SenSpot™: 0.00016 degree or 0.5 arcseconds.

This system reduces installation cost and time for owners/authorities to get the real-time data they need for retaining walls monitoring. A unique capability of Resensys wireless gauges is to measure at very high precision, while providing ultra-low power usage to allow short and long term monitoring.


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High-resolution tilt measurements (2D-roll & pitch) in SenScope^TM software for an installed HRT gauge (High-Resolution Tiltmeter) on a panel of a retaining wall
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Wireless Dual-Axis Inclinometer (Tiltmeter) SenSpot^TM installed on a face of a retaining wall and its movement and sign conventions (Roll: tilting of the wall in longitudinal direction & Pitch: tilting of the wall in transverse direction)

A typical retaining walls monitoring system includes the following components:

• Wireless Tilt/Inclination SenSpot™: sensors are attached to the retaining walls critical sections. The number of                                                      gauges required per retaining wall is usually dependent upon the design,                                                                         existing issues on members and retaining walls monitoring needs.

• SeniMax™: is a wireless data logger gateway that is connected to the cellular or satellite networks; it wirelessly                          collects SenSpot™ data at the site and sends it to a cloud database server (one SeniMax™ can cover as                           many as 100 SenSpot™ sensors and devices within its wireless communication range).

• SenScope™: software for data analysis and visualization, data export, automated alert management, thermal                            analysis, and retaining walls data analysis. For retaining walls monitoring, Resensys SenScope™ has                     the feature to provide alert notifications when pre-set data thresholds have been exceeded (by                             sending warning email/text/notification to corresponding authority).

The figure below shows a picture of a practical Resensys Structural HealthMonitoring (SHM) system, which can be used for Retaining Walls Monitoring.