Working with HM Government of Gibraltar over 10 weeks in Gibraltar
CAN designed and installed a high-capacity rockfall catch fence in Gibraltar to help protect the highway and nearby properties from falling rock. The project delivered a practical stabilisation solution while overcoming challenging ground conditions and minimising disruption to the surrounding area.
This project required CAN to design and install a 5000kJ rock catch fence system at the toe of a large sand and talus slope. Located beneath towering cliffs on the East side of Gibraltar, the catch fence was installed to protect both the highway and private properties below.
The chosen solution was the Geobrugg RXE-5000. In designing this catch fence, CAN worked closely with Geobrugg in order to ensure that the finished product met the requirements of the specification, but was also buildable in an efficient and cost-effective manner.
The catch fence is secured with 75 hollow bar anchors and micro piles. Groups of anchorages were encased in reinforced concrete foundations supporting the 7.5m high posts.
The poor ground conditions of weathered sand and rock meant that large amounts of temporary works were required to stabilise the slope above the worksite, in order to safely excavate for the large RC foundation pads and to provide benches for vertical drilling.
It was not an option to use excavator-mounted drill rigs on temporary benches due to the limitations on width and allowable bearing pressures. Therefore, CAN’s custom-built slope-mounted drill rigs were used to install the inclined anchors.
Utilising quickly installed temporary catch fences, along with existing catch fences as protection, CAN was able to carry out the works safely, protecting the road users below. Additional careful planning kept road closures to a minimum for concrete wagons and craneage.
