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Historic hotel's function room saved from 12m deep sinkhole in 3 days

Challenge

A 4m-wide, 12m-deep sinkhole was discovered under the main function room of the Grade II listed Queens Hotel. The traditional mass-fill solution meant months of closure and cancelling all booked weddings.

Solution

Geobear injected a specialist lightweight geopolymer to fill the 25m² void. The material was 70% lighter than the alternative and completed in 3 days, saving all bookings.

3 days

Project completion time

12 metres

True depth of the void

25m²

Total affected area

70% lighter

Than the mass-fill concrete alternative

Background

The Queens Hotel, a Grade II listed building in Cheltenham, uncovered a large sinkhole (approx. 4m across) under its main function room, the Regency Room. The void was dangerously close—just 1.5m from the hotel's front façade. Tension cracks were visible, indicating a risk of further collapse.

Challenge

The hotel faced a catastrophic failure. The sinkhole, suspected to be a failed well, put the building's foundation at risk. The main alternative, mass concrete filling, was rejected for several reasons:

 

Time

It would have closed the function room for months, forcing the cancellation of all upcoming wedding bookings.

 

Risk

The full depth of the weak ground was unknown, and the invasive works could further weaken the soils beneath the hotel's main façade.

 

Access

Site access for heavy plant and concrete delivery was extremely restricted.

The client was able to honour all their bookings and bring the room back into use "several months ahead of time."

Solution

Geobear was called in to provide an emergency solution. Our own dynamic probe testing revealed the issue was far worse than it appeared: the void extended 12m deep and affected a 25m² area.

Our engineers designed a two-part geopolymer solution:

Deep stabilisation: A specialist resin with a "lengthy liquid phase" was injected into the deepest part of the void to handle potential water and stabilise the soils at depth.

Lightweight fill: A different geopolymer was used to fill the main irregular-shaped void.

This solution was at least 70% lighter than the mass concrete option, placing minimal new load on the surrounding weak ground.

View into the void below Queens Hotel Cheltenham being filled by Geobear
View of void filled with geopolymer

 

Results

The entire project was completed, on time and within budget, in just 3 days. The hotel remained fully open, and the solution was so fast that a wedding reception took place in the Regency Room as planned the following weekend. The client was able to honour all their bookings and bring the room back into use "several months ahead of time."

Facing an unexpected ground failure?

Don't let a sinkhole or void shut down your business. Get an immediate, lightweight, non-invasive solution.

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