October 20, 2023
Nestled in the picturesque village of Gerb, Catalonia, Spain, the El Espígol boulder, or Penya de l’Espígol, has recently drawn attention due to its potential instability. Back in 2019, this colossal rock raised concerns when deep cracks marred its surface, setting the stage for the El Espígol Rock Stability Monitoring Project. A collaborative effort between the Provincial Council of Lleida and contractor Kuroba Quatre SL, this ongoing project exemplifies the imperative of constant vigilance and swift action to protect communities from impending natural disasters. In this blog, we delve into the origins, timeline, and instrumental strategies that underscore the significance of proactive geotechnical engineering and hazard management.
In the charming village of Gerb, Catalonia, Spain, there's been a growing concern about the safety of the El Espígol boulder. Locally known as Penya de l’Espígol, this massive rock stands 32 meters tall and spans 24 meters wide. Back in 2019, it was flagged as "potentially unstable." This set the stage for the El Espígol Rock Stability Monitoring Project, a joint effort between the Provincial Council of Lleida and contractor Kuroba Quatre SL. This project underscores the importance of ongoing vigilance and quick action when it comes to protecting communities from potential natural disasters.
So, what triggered the need for this project? Well, it all started when deep cracks were spotted on the rock's face. This discovery got the folks in Gerb pretty worried, and rightfully so. To address these concerns, the town council decided to investigate further, leading to the realization that constant monitoring was the way to go to prevent a potential disaster.
Now, let's talk about the timeline. The El Espígol Rock Stability Monitoring Project kicked off in December 2021, and it's still ongoing as of February 2023. We're now well into the second year of this project, and it's already given us crucial insights into the condition of the rock, prompting some rapid actions to secure the area.
When it comes to the tools and gear used for monitoring, Kuroba Quatre teamed up with Encardio-Rite, and they opted for some no-frills equipment. They started off with crack meters and wireless tilt meters. The crack meters helped keep tabs on the width of any existing cracks in the rock, while the tilt meters tracked changes in the rock's tilt. On top of that, they used load cells to measure the force on the rock bolts and piezometers to monitor water pressures beneath the surface.
The data collected by these instruments was sent to a central server through wireless RF data loggers and a gateway. This made it easy for all the people concerned to access and use the data in almost real-time. And just to add another layer of security, they had an alarm system that would go off in case of any major movement, thanks to an extensometric sensor.
As things progressed, they expanded the system with more load cells and piezometers. They upgraded the alarm system to make sure that any sensor exceeding its limits would set off the alarm. This way, they weren't relying on just one sensor to keep them safe.
Surprisingly, within two weeks of setting up the monitoring, it became clear that the rock was in trouble. The tilt meters recorded a whopping 18-degree tilt, and the crack meters showed a displacement of almost 5 mm.
No time was wasted. They swiftly took action, putting up the metal mesh and installing rock bolts to stabilize the situation. They also added more instruments to keep an eye on things, all the while receiving real-time data to make sure they stayed on top of any changes.
In the end, the El Espígol Rock Stability Monitoring Project stands as a powerful reminder of how essential continuous monitoring and quick responses are when it comes to safeguarding our communities from potential natural disasters. This case study shows us the significance of being proactive and staying alert in the field of geotechnical engineering and hazard management.
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