STRICT CONTROLS over construction work in Moscow remain in place after a series of ground collapses in the city in recent months, EF can report.
Scrutiny of construction work in the city ordered by Mayor of Moscow, Yuri Luzhkov continues amid concerns that other major ground failures could follow.
'It's still strictly necessary for each project to be reviewed at a state level, ' Professor Vladimir Gagin from the Moscow State University of Civil Engineering told EF.
Professor Vladimir Baulin, exhead of the Geocryology Research Department at the Russian Federal State Enterprise, said a lack of investment in geotechnical services, while a spate of underground shopping centres and car parks have been built, had made much of the city's ground unstable.
'In Moscow in the last 10 to 15 years, construction companies in pursuit of profit have minimised the expenses for geotechnical research and have therefore increased the structural risks, ' he said.
He added that the recent collapse of a major section of the main road into the city, the Leningradsky Prospekt road - an event which sparked the current review of geotechnical construction work - was the result of inadequate geotechnical testing of the ground underneath.
'The collapse of the Leningradsky Prospekt was caused by infringement of construction technology and design, ' he said.
UK consultant Arup associate Steve Macklin, who has worked on major projects in the city, said the danger was particularly acute because construction of underground structures could destabilise 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 strata.
Holes in the highly permeable limestone had allowed groundwater to percolate through and this had slowly opened up voids varying in depth from 10m to 100m.
Some of the newly built basements were in danger of adding stresses around these voids, he added.
Baulin agreed, and added that soils with Karst voids were affecting about 20% of Moscow, particularly in the west and south west of the city around the Moscow River.
Macklin believes Karst hazard maps would improve the chances of detecting these caves: 'Then you could start to come up with a predictive model, ' he said. But existing mapping of ground conditions in Moscow is limited, he told EF.
Baulin said the most complete information about Moscow's substratum is held by the Mosgorgeotrust enterprise.
He said the city authority had started a long term project to map ground conditions, but the work was far from complete.
Fast completion of the maps is crucial because of Moscow's continuing construction boom that includes underground structures.
'To ban construction of underground car parks and other underground structures is useless, while the city is growing both upwards and downwards, ' said Baulin.
'What's important is that this development should be provided for by highly professional assessment of geological conditions of the construction site.'