A BOOM in basement construction in Moscow has put much of the ground in the city at risk of collapse, engineers told NCE this week.
A wealth of underground car parks and shopping centres, built amid a construction boom in the Russian capital in recent years, have put an estimated 15% of the city's surface at risk of collapse, say reports.
Arup associate Steve Macklin, who has worked on major projects in the city, told NCE that there was a danger that basement structures could destabilise the many existing caves lying underneath Moscow.
These were formed by chemical erosion known as 'karst' of the layers of mudstone and limestone, which comprise the city's substratum.
Over the years, holes in the highly permeable limestone have allowed ground water to percolate through the ground, opening up voids varying in depth from 10m to 100m.
Some of the newly constructed basements were in danger of adding stresses around these voids and disturbing their stability, Macklin said.
'People are doing things that could disturb the stability of these caves, ' he said. 'A 40m deep basement will change the loads in the ground. Karst hazard maps would improve the chances of detecting these caves and then you could start to come up with a predictive model.' Existing mapping of ground conditions in Moscow is limited.
A major section of the main road into the city, the Leningradsky Prospekt road, collapsed recently and mayor of Moscow Yuri Luzhkov is reported to have ordered a review of construction work in the city amid concerns that other major ground collapses could follow.
Hugh Doherty, director of Russia and central Europe at consultant Waterman, structural engineer on a proposed Norman Foster-designed tower in Moscow, said: 'Ground conditions in Moscow can be quite a challenge, but there's no reason to get overly concerned so long as the work is done in the proper manner.'