A serious accident occurred in the province of Lualaba, in the Democratic Republic of Congo: the collapse of a portion of the earth covering the access tunnel to a cobalt mine. The landslide event caused the deaths of at least 32 workers, according to local authorities. The video demonstrates the significant extension of the landslide and its impact on the adjacent areas. Rescue operations are still underway and the toll of the serious accident could worsen.
Although the site had been declared unusable due to recent heavy rains, some workers were in the area at the time of the collapse, and subsequently suffered the collapse. Local authorities have stated that the cause of the landslide can be traced back to the rain events of the previous days. The precipitations, in fact, have favored abundant infiltrations of water into the overlying soil, altering the hydraulic regime normally present in the layers of the “coverage” and, consequently, the stability of the geotechnical system which until now allowed the transfer of stress to the lateral terrain areas.
Water, penetrating the solid skeleton of the ground (which has its own porosity), can – in general – cause a reduction in resistance: the result, as in this case, can be the trigger of landslides or structural failures, the latter only if there are structural works that interact with the layers of soil affected by the phenomenon.
The first reconstructions incorrectly speak of a “collapsed bridge”, but technically it is an excavation cap formed following mining operations. This appears to lack real engineering, according to the current documents and information that can be found online. The phenomenon is comparable to an induced landslide, linked to the variation in interstitial pressures and the loss of balance of the layers of soil overlying the excavation, already in themselves weakened by the presence of the works and – in the specific case – not equipped with an appropriate cambering system capable of guaranteeing the right condition of equilibrium (as happens, for example, inside a tunnel).
