Stabilization of a building under construction after a collapse

Following the appearance of a 2 m diameter fontis during the construction of a building in Yerville (76), the entire area was consolidated with expansive resin injections in order to be able to welcome future inhabitants.

The commune of Yerville, located 30 km from Rouen, has been developing for several years with the establishment of new housing estates and an activity zone. During the completion phase of the construction of a set of buildings, a disaster appeared in front of the stairwell of a building in R + 2.

A 3,5 m deep collapse

Despite the preliminary geotechnical study, a sunk about 2 m in diameter on the ground and 3,5 m deep surprised all stakeholders during the construction of the trenches for the supply networks. Water infiltration caused by heavy rain may have acted as a catalyst in the presence of a underground mining sand and gravel, known as stony. The proximity of the building and one of its piles located less than 3 m from the collapse, entailed a risk of destabilization for the residential structure.

An expansive resin to durably consolidate the cobble

Following the various penetrometer drilling and destructive drilling indicating the absence of residual voids, the solution URETEK Deep Injections^® was chosen to stabilize and strengthen the fontis area. After backfilling the collapse, expansive resin was injected in a column to treat 166 m3 of reworked soil up to the base of the collapsed cavity located 13,5 m deep. In just 4 days, the injections made it possible to strengthen the area thanks to a mesh of precise injections. The two comparative tests with the penetrometer were able to conclude from the relevance and success of this action to secure the residential area in the long term.

Filling a marnière or cailloutière before collapse, what solution?

After detection of a underground cavity of natural or anthropological origin without collapse, URETEK^®offers with the process Cavity Filling an exclusive filling solution to improve the resistance of floors. It consists in propelling deactivated clay balls in the volume to be filled with a resin agglomerating the grains until perfect bonding is achieved in the upper part of the cavity. This process then allows a secured very fast risk areas avoiding the appearance of fonts like that of Yerville.