Building Ultra Tall on London's Clay

[mulattokid]

This is a subject of discussion that came up in the Shard thread.

When I was young I recall being taught that it was very very difficult to build skyscrapers on London Clay, or any similar substrate in any location.

In fact, this was sometimes given as one of the main reasons why building heights had to be limited in London.

Does anybody else recall this assertion? Does anyone have any information on this matter?

I was given to understand that only in fairly recent years has technology caught up with the desire to build ultra high buildings in such locations

[london lad]

I heard the same that the clay was too soft for tall buildings & its only in recent decades that this has been be overcome. However up to the late nineties the city (as well as most other London bourghs )had a very anti highrise policy hence no new towers in the city until Swiss Re. The success of CW saw the city change its policy hence the raft of proposals in the last 7 years.

[mulattokid]

Funny you should say that..I just found this:

'The repeal of the London Building Act in 1956 opened the way for towers to be built in London, but it was the work of engineer A W Skempton, who pioneered bored piles, that made the London clay able to support them.

http://www.bdonline.co.uk/story.asp?storyCode=3080008

[nezzybaby]

^I think you've answered your own question, but essentially it is more expensive and more complicated to build tall, but not impossible or infeasible.(unfeasible... charlie help!)

[dirtydog]

Originally Posted by mulattokid

I was given to understand that only in fairly recent years has technology caught up with the desire to build ultra high buildings in such locations

The existence of T42 proves that office towers were technically possible in the 70s, and thus that the lack of any further skyscrapers in the City for 30 years was due to other reasons.

[RoryT]

like i mentioned in the shard thread; i believe london had the means to build an ultra tall on it's London clay when NYC built their Chrysler and Empire State Buildings.

London has always had a strong knowledge base; producing some of the greatest engineers ever. If required to, London's engineers could have overcome the obstacle of building high on poor surface material.

I doubt finances would have been an issue

So the main factor restricting high rise development in London must have been the planning laws or a lack of need or desire to build upwards.

Also, didnt the Victorians propose some very tall buildings?

[mulattokid]

I agree......I think it must be attitude too. There is an old entertainer called Max Bygraves..a Londoner. I saw him interviewed many reayrs and he said that his father told him the savoy hotel and others along the north bank were skyscrapers (D'art Deco buildings of about 12 stories) when he was a boy in the 1930's.

I could just be a question of perspective.

The Victorians did want to build some major towers. In this case, I think it was money that was the issue. In which case, the knowledghe might have been there, but just too expensive to utilise, even for the extravagant, experimental and investing Victorians.

They would have made the technology, but you can bet it would involve impossibly gigantic foundations...as mentioned above....bore hole piling is a recent invention.

[gothicform]

I saw him interviewed many reayrs and he said that his father told him the savoy hotel and others along the north bank were skyscrapers (D'art Deco buildings of about 12 stories) when he was a boy in the 1930's.

actually shell mex house (which at the time was a different building called the cecil hotel) was. it is, if not the first, then one of the first skyscrapers in the world according to the definition. there's some argument over whether it is as it was finished a few months later than the first american one but had taken longer to build as it was bigger.

[mulattokid]

As always...a good point!

[Bones]

Tower 42 has very deep foundations. I think the book "London High" said they were 60 metres. (Emporis says 50 metres, 164 feet) An underground stream was found unexpectedly during construction which lasted unbelievably from 1971-1978.
Chicago also has soft ground. The technolgy of caissons or piling for skyscrapers was developed here for that reason decades ago.

[Chief]

There are a few issues at play here.

One is that tall buildings also usually have deep basements. London has a long history, and archaeological obligations on developers mean that access for site surveys, digs etc can add an unknown amount of time to a building programme. This one strong incentive not to build deep.

Another is, as mentioned, the London clay. It's wet and difficult to dig through, and this makes it more difficult to design a stable structure for the building you want to build on top. More difficulty = more time = more money. It's only more recently, particularly with advances in computer analysis packages and experience, that it's become more economical to do so.

Thirdly, it's only recently that London has begun to really catch up with and overtake New York in terms of its status and size as a financial centre.

Both these factors - engineering capability and cost/uncertainty - I believe made it more difficult, but not impossible, to build big and deep in London. You can solve just about any problem by throwing enough money at it. The two issues above meant that the economic incentives for building big had to be even greater in London than they did in New York, and it's only over the last decade or so that these issues have come into the correct alignment for us to see the kind of development we're seeing today.

[Black Cat]

Chicago and Shanghai both have very soils with poor bearing capacity, very problematic for supporting high rise buildings, yet this did not prevent tall structures from being constructed. London is no worse, and probably better. In London, St Pauls and Westminster Abbey for example are significant structures and neither have been known to settle, though the earlier St Pauls tower did suffer problems and had to be butressed. As said before, the issue for not building high rises in London was not soil conditions but due to prevailing attitudes about the acceptabililty of tall commercial or residential buildings. Building height limits were introduced following Queen Victoria being very unhappy to have her garden overlooked by residents of Queen Anne's Mansions built in the 1870s, which rose to 180 ft high, and also obstructed her view to the Parliament buildings (Victoria Tower). Thereafter height limits were introduced in London.

[Bones]

I have heard that the skyscrapers in Shanghai are slowly sinking.

[Cat man do]

http://www.news24.com/News24/World/N...426200,00.html

The while city is sinking with the skyscrapers being blamed in part.

[dirtydog]

Originally Posted by Bones

I have heard that the skyscrapers in Shanghai are slowly sinking.

China's largest city, Shanghai, is to slash construction of new high-rise buildings to try and stop the city from sinking under the weight of all the concrete and steel.

Shanghai is reportedly sinking 1.5cm each year
Parts of Shanghai are now sinking at a rate of one-and-a-half centimetres a year, largely as a result of a massive building boom there over the last 10 years.

According to Saturday's China Daily, tall buildings look nice but they can also cause problems - a fact that Shanghai is rapidly finding out.

Over the last decade a massive building boom has totally transformed the skyline of China's largest city.

According to the paper, at least 3,000 high-rise buildings have gone up; another 2,000 are on the drawing-boards.

World's tallest building

Shanghai is already home to China's tallest building and a new building now under construction will be the world's tallest.

All this in a city that is, in effect, built on a drained swamp.

Now, as the city gradually sinks below the level of the Huang Pu river, the city fathers are getting cold feet - or should that be wet feet?

Construction of new skyscrapers is to be cut, but with so many already built or under construction it may not be enough to stop Shanghai's sinking feeling.

http://news.bbc.co.uk/1/hi/world/asi...ic/3105948.stm

crazy.

[TomD'07]

Originally Posted by Bones

I have heard that the skyscrapers in Shanghai are slowly sinking.

Shanghai has massive flooding problems as its built on alluvial soils (yellow or yangtze river delta??). I read that sea water can filter through and upwell under buildings closest to the sea. Coupled with sea level rise of ~50cm in the next 100 years then theyre going to have huge problems.

[mulattokid]

I know salisbuy Cathedral is built on some kind of reed mat. I imagine that Westminster cathedral is too, bien located right by the river.

Victoria Tower is a Victorian skyscraper is it not? That must have deep foundations.

I recall that work on the new Westminster Station had to be stopped, as St. Stephens Tower was movign back and forth. I believe it transpired the the ebb and flow of theThames was the cause of the oscillation.

[dronkula]

I, probably incorrectly, always through that Dubai was kinda built on sand?

[mulattokid]

Originally Posted by dronkula

I, probably incorrectly, always through that Dubai was kinda built on sand?

" It is a foolish man that builds his house on sand " The Good book (somewhere)

[gothicform]

I know salisbuy Cathedral is built on some kind of reed mat. I imagine that Westminster cathedral is too, bien located right by the river.

you have misremebered the cathedral i think. that is winchester cathedral which was at the beginning of the 20th century collapsing. investigations by architects found it was built on foundations only 6 feet deep with a reed mat under it that kept it floating above a swamp!

Restoration work was carried out by T.G. Jackson during the years 1905–1912, including the famous saving of the building from total collapse. Some waterlogged foundations on the south and east walls were reinforced by a diver, William Walker, packing the foundations with more than 25,000 bags of concrete, 115,000 concrete blocks and 900,000 bricks. He worked six hours a day from 1906 to 1912 in total darkness at depths up to 6 m, and is credited with saving the cathedral from total collapse. For his troubles he was awarded the MVO.

in other words, one man laid the foundations for the cathedral underwater. a huge achievement that made him one of the most famous people in the country being awarded a personal pension, either by the king or parliament, i cant remember which whilst becoming a member of the royal victorian order and being a commoner was unheard of. i believe that walker died of spanish flu at the end of ww1.