Ground cavities are voids below the surface that may not be visible from above, yet can threaten the stability of structures if their roofs collapse or the soil above them moves. That is why detection before construction is advised on sites where cavities are suspected.
How are they detected?
- Ground penetrating radar (GPR): picks up changes in the layers near the surface.
- Seismic surface waves (MASW): estimate layer stiffness and reveal weak or hollow zones.
- Electrical resistivity tomography (ERT): shows contrasts in the properties of the layers beneath the site.
Once suspect locations are identified, they are verified by drilling holes at those points.
How are they treated?
When cavities are confirmed, holes are drilled at their locations and injected with cement grout to fill the voids. This improves the soil and raises the safety and stability of the structure.
Our experience
Our projects include cavity probing for Riyadh Metro Line 6, as well as cavity detection and grouting for residential and commercial buildings in Riyadh.