Collapsing metastable unsaturated macroporous loess ground in Belarus, Ukraine, Southern Russia, parts of Central (Middle?) Asia, Western Siberia and the Caucasus/ Kopet Dagh regions (work in progress).

Ian Smalley, Giotto Loess Research Group, Waverley Materials Project, School of Architecture, Nottingham Trent University, Nottingham NG1 4BU, UK ian.smalley@ntu.ac.uk

Introduction #1
Collapsing ground causes widespread geotechnical problems. The typical collapsing ground system is an unsaturated metastable loess soil and the problem is at its worst in China and in parts of Eastern Europe and the FSU where thick loess deposits coincide with regions of urban development and industrial activity. Much of the literature is in Russian and many of the most interesting sites are within the boundary of the former Soviet Union; two facts which have combined to prevent a general worldwide study of these critical materials. Progress on unsaturated loess studies within the Soviet Union was handicapped by a failure to agree on such basic questions as the nature of loess and the mode of its formation and by the dispersal of specialists throughout the Union.

We propose a study on collapsing loess in the FSU, and a first step will be to define the areas of occurrence and make a simple definition of loess type. Some gross simplifications are involved in this initial enterprise. We base our distribution studies on the map by Abelev & Abelev(1968) showing 'collapsing loess ground within the territory of the USSR'. This still appears to be a useful map, but more detail is given on a later presentation by Sergeev et al(1986). These maps will eventually be reproduced and circulated in the Loess Letter map series; they should be available at GeoEng 2000.

Quotation: Trofimov 1990
Collapsibility is a specific property of loess rocks of different geneses(aeolian, slopewash, alluvial fan, alluvial, lacustrine-alluvial). It is expressed in the ability of strata of loess rocks to decrease their volume under a constant acting load, as a result of which collapse of the mass's ground surface and deformation of engineering structures occur. This property makes loess soils fundamentally different from many other types of disperse soils. The genesis of collapsibility is an interesting and complex question, with which many Soviet researchers have been engaged(Yu.M.Abelev, V.P.Anan'ev, I.M.Gor'kova, N.Ya.Denisov, N.I.Kriger, A.K.Larionov, G.A.Mavlyanov, A.V.Minervin and E.M.Sergeev).

Regions: Seven loess regions are proposed; these are initial suggestions only

1. The Western Loess: This is by far the largest and most important region. In Belarus there appears to be relatively little loess; some patches near Minsk. To the south, in Ukraine there is widespread loess- this is a region with many geotechnical problems. This is glacial loess of northern origin, the river Dnepr has moved and distributed much material. This zone takes in the Crimea and spreads north to Orel and nearly to Moscow, and east to Kazan. It includes Rostov-on-Don and the site of the Atommash factory collapse.

2. The Caucasus + Kopet Dagh: A defineable region of mountain loess associated with the Caucasus mountains- stretching roughly south-east from Tbilisi. Another zone, east of the Caspian Sea, on the southern boundary of Turkmenistan, mountain loess fron the N.Iran mountains, near Ashkhabad, can be included.

3. Central Asia: The loess around Alma-Ata, Tashkent, Dushanbe, Samarkand and Bukhara; classic mountain loess, material from High Asia carried by river into desert regions and deposited in piedmont regions or desert fringes. Abelev & Abelev show substantial deposits to the west of Lake Balkhash. The Amu Darya and Syr Darya rivers have carried much loess material into desert regions; it is the irrigation of these loess soils which has led to the demise of the Aral Sea.

4. The Orsk-Omsk Loess: It is tempting to call this the Ural loess but origins are obscure. Material is certainly carried down the Ural River towards the Caspian Sea and this might be mountain loess with a particle origin in the Ural Mountains. This could apply only to the western part of the region near Orsk. The Omsk loess is close to the Irtysh river which flows to the north-east out of the Altay mountains. There is loess all along the Irtysh to the south of Omsk, and this must be classic High Asian mountain loess. Category 4 is probably going to need a sub-division, and further careful consideration.

5. The Tomsk loess, or the Ob Loess: Tomsk represents the northern limit of this loess region; the Ob moves material north from the mountains. Surgut is well to the north of the loess region. Abelev & Abelev show no collapsing loess in the W.Siberian plain.

6. The Kansk loess, or the Yenisey Loess: To the east of region 5 and similar in style; mountain loess supplied by the river Yenisey.

7. The Irkutsk Loess: A smaller region, associated with the Angara river, north of Irkutsk. No deposits shown east of Lake Baikal.

In each of these regions there are major towns which suffer, to some degree, from subsidence problems caused by hydrocollapse in the unsaturated loess. Particle origins are glacial or mountain, in most cases substantial river transport is involved, the final deposition is by airfall sedimentation. A more elaborate formation model may not be required. Subsidence problems arise via syngenetic processes and hydrocollapse operates as defined by the 'small clay' model.

For discussion: is each region a large, medium or small loess region? Is the loess of mountain or of glacial origin? Does any associated river flow essentially to the north or to the south?...

Quotation: Kriger & Kotel'nikova 1978 
The origin of loess is still in dispute. In our opinion, there is now proof of the sub-aerial origin of loess, but loess deposits may also be subaqueous. There are strongly differing ideas concerning the degree of weathering of loessal material. Even a short time ago loess was regarded as a weathering crust, but Kriger has now shown that the mineral in loess have a slight degree of weathering. Clearly epigenetic weathering did not play an important part in formation of the properties of loess. Vysotskiy showed that in steppes, from a depth of 2-3m downward, the loess usually exhibits a 'dead' horizon with a low moisture contant(<10%) of the deposit which is not subjected to seasonal fluctuations. Here moisture transfer is not intense. Finally Denisov developed our knowledge concerning the undercompaction of loess with respect to its stressed state.

Introduction #2 [Reprise]
The western part of the FSU is an important loess zone and there are significant deposits in the southern parts of the region, relating to the high border mountains and the Central/Middle Asian deserts. Despite its interesting nature and widespread occurrence this loess is not well known in a worldwide sense, it does not have the stature in the world literature that it deserves.

There are various reasons why the FSU loess has not been fully appreciated: the literature is in Russian- which is a major world language, but not one which is widely understood outside the FSU- so the debate on the FSU loess has always tended to be internalised.. And of course for many years this internalisation was deliberate, a political policy of non-contact made the dissemination of useful and interesting information very difficult. In Western Russia and Ukraine the coincidence of thick loess and high concentrations of urbanisation and industry is greater than in any other part of the world and this has meant that a high proportion of loess publications in Russian deal with foundation engineering and related topics which do not have the worldwide audience which say palaeoclimatic studies have.

During the 1990s this situation might have changed but in fact little has happened. The political constraints have largely been replaced by economic constraints. The vast Russian loess effort which was separated from us by politics and language is now a modest effort separated from us by economic barriers. The Soviet Union used to be a major participant in INQUA activities but at Durban in 1999 all that had vanished.

A consequence of this is that if a general account of the FSU loess is to be written it will have to be done by outsiders. C18 and the Loess Commission perceive that what we need is a general account of loess and subsidence problems in the FSU-major fields of study and endevour by generations of Russian speaking scholars must be acknowledged and appreciated. In the 175 years of loess research the major Russian contribution has been in the geotechnical field- major figures like the Abelevs, Denisov, Krutov, Minervin, Kriger, Sergeev etc deserve their places in loess history. This account is a first attempt at some of these aims. Our aims are to provide a description of loess distribution in the FSU and to say something about the Russian approach to problems in engineering geology and ground engineering. Some terminology will have to be inexact; we deal with literature written in the Russian language, mostly by Russians, but of course also by other nationalities living within the borders of the FSU; so inevitably Ukrainians(say) will be described as Russians, despite our efforts to avoid this. There are problems even at the level of Central Asia vs Middle Asia, and Central Europe vs East Europe, so terminological caution is required

A brief history of collapsing loess problems in the USSR was given by Krutov(1987). He suggested that about 10% of the territory of the USSR was vulnerable to collapsing soil problems and indicated that about 30% of construction in the 1960s-1980s was in collapsing soil regions. Problems arose in the 1920s with irrigation systems in Central Asia and the North Caucasus, and oil industry construction at Grozny. In the first five-year plans large metallurgical and machine manufacturing plants were constructed at Zaporozhe, Nikopol, Dnepropetrovsk, Zhdanov, Kherson and Kuznetsk, also irrigation systems and hydraulic structures in Central Asia, the North Caucasus and Transcaucasia[Krutovs place names-note that some have changed since 1987].

In the years after the Great Patriotic War very large industrial structures e.g. VAZ, KamAZ, Atommash, KZTE etc were built and there was widespread residential and industrial construction in the Ukraine, the Rostov region, Siberia and Central Asia.The first solutions(according to Krutov) to the related foundation problems were made by Yu.M.Abelev. He was certainly publishing papers on flexible foundations in the early 1930s. Krutov lists as having made significant contributions: M.Yu.Abelev, V.P.Anan'ev, Kh.A.Askarov, L.G.Balaev, Ya.D.Gil'man, V.N.Golubkov, M.N.Goldstein, A.A.Grigoryan, N.Ya.Denisov, S.N.Klepikov, A.A.Kirilov, N.I.Kriger, A.K.Larionov, I.M.Litvinov, G.M.Lomize, G.A.Mavlyanov, A.A.Musaelyan, A.A.Mustafaev, N.A.Ostachev, A.L.Rubinshtein, E.M.Sergeev, V.E.Sokolovich, R.A.Tokar and N.A.Tsytovich.

Osipov & Sokolov(1995) commenting nearly ten years later, suggested that 55 towns and cities in the FSU suffered from loess subsidence problems[it would be nice to have a list of these]. They proposed that the extent of collapsing loess in the FSU amounted to about 3.5 million km2. They also listed six monographs to give background to the collapsing loess study:

1. V.P. Anan'ev 1964: Mineralogical Composition and Loessial Soil Properties

2. L.G. Balaev & P.V.Tsaryev 1965: Loessial soils of Central & Eastern Pre-Caucasus Area

3. N.I. Kriger 1965: Loess, its properties and relation to the geographical environment

4. V.I. Krutov 1982: Basements and Foundations on Collapsible Soils

5. A.K. Larionov 1971: Research Methods of Soil Structures

6. E.M. Sergeev, A.N.Larionov & N.N.Komissarova 1986: Loess Soils in the USSR

Longer versions of some of these references will be given in later episodes of this story; they appear here as listed by Osipov & Sokolov. Note Kriger 1965- one of the truly great classics of loess literature; and also Sergeev et al who provide a useful map of loess in the USSR. Kriger in 1986 published a book completely devoted to loess subsidence which includes the only worldwide map of collapsing soils ever published[more on books in the next section].

Publications
There are many books relating to our topic; many were published in very small print runs; many are totally unavailable and inaccessible- but we can identify a few classics. We mention initially three works: Loess, its properties and relation to the geographic environment by N.I.Kriger(prepared for the INQUA Congress in the USA in 1965); Fundamentals of design and construction on collapsing macroporous ground by Yu.M.Abelev & M.Yu.Abelev, published in Moscow in 1968(there might be a later edition); and Loess soils of the USSR by Sergeev, Larionov & Kommissarova, published in 1986. The Kriger book is a great classic, written to express Kriger's view that climatic zoning was very important in loess formation, it was however written from a foundation engineering institute by a leading expert on loess collapse. It is one of the few Russian texts to contain an adequate bibliography(which was republished separately by Loess Letter in 1984). Only 1350 copies of this book were printed, and very few were exported, so it is no surprise that this great classic is not well known, and not widely appreciated in the non-Russian speaking world.

The Sergeev et al (1986) study, in two volumes, gives a more up to date view of the FSU loess; part one deals with genesis, post-genetic changes and engineering-geological characteristics of loess soils; part two looks at methods of economic development of areas composed of loess soils ; part three considers artificial improvement of loess soils. Volume one which contains parts 1 to 3 makes do with 38 references; Kriger is not mentioned. One gets the impression, looking at Russian literature, that there is a tradition of not mentioning the rivals, and also that there is a great rivalry between the universities and the research institutes. The size of the USSR meant that local expertise was very important so that the major centres boasted their own particular scholars: Anan'ev in Rostov-on-Don, Lysenko in Leningrad, Mavlyanov in Tashkent etc. Something to be discussed in future sections will be this location of specialists, and an attempt will be made to link investigators to techniques; everybody knows that Sokolovich is the expert on chemical stabilization and thast Krutov specializes in dynamic compaction; we need to identify more places, more techniques and more people.

Key Reference: Jefferson, I.F., Evstatiev, D., Karastenev, D., Mavlyanova, N. & Smalley, I.J. 2003. Engineering geology of loess and loess-like deposits; a commentary on the Russian literature. Engineering Geology 68, 333-351.