F R O M T H E E X P E R I E N C E O F C O N S T R U C T I O N ORGANIZATIONS

EFFICIENT

METHODS

ON P E R M A F R O S T OF

CONSTRUCTING

OF

SOILS THE

FOUNDATION (FROM

THE

NORIL'SK

M . V. K i m

ENGINEERING

EXPERIENCE

COMBINE) UDC624.139.54

The Noril'sk Mining and Metallurgical Combine and the city of Noril'sk were built under the rigorous climatic conditions of the Arctic region. The foundation soils at the construction sites a r e p e r m a f r o s t and contain much ice. During the f i r s t decade of constructing Noril'sk there were many cases of the deformation of buildings and s t r u c t u r e s built on the frozen ground. The number of buildings deformed as a consequence of disturbance of the stability of the foundation soil following its thawing reached 30 at the s t a r t of the 1940's. At the f i r s t stage of construction of Noril'sk the builders, of course, were guided by the small body of l i t e r a t u r e data concerning construction on p e r m a f r o s t soils and by the recommendations of OST 90032-39 [10]. However, the Noril'sk builders creatively approached the regulations and technical specifications and r e v i s e d them on the basis of their experience and observations [4, 5]. The design and construction of the Noril'sk Combine and the city of Noril'sk involved a long search f o r efficient designs and industrial methods of construction, their verification in practice, and continuous improvement. Each stage involved the s e a r c h f o r economic designs and efficient methods of foundation engineering which would ensure longevity and operational reliability of the buildings and s t r u c t u r e s being built. By the middle of the 1940's the number of deformed buildings and structures (of those newly built) markedlydropped, although the volurae of construction increased many times. This was promoted mainly [2, 3]: a) by thorough engineering surveys and site explorations in the region of Noril'sk which preceded the development of the designs of the combine and c i ~ and which elicited the specific c h a r a c t e r i s t i c s of the climatic and p e r m a f r o s t conditions of the region as a whole, and, in g r e a t e r detail, the peculiarities of the frozen-ground conditions of each construction site; b) by selecting the method of using soils as bases by thorough study of the plans of the city, industrial sites, and individual buildings and s t r u c t u r e s , with consideration of the technical characteristics of the objects and specific frozen-ground situation of the construction sites; c) by developing designs which would p e r m i t using industrial methods in constructing the substructures° d} by laying the sewers in such a way as to preclude the thermal effect of the pipes on the frozen bases of buildings and structures; e} by the s t r i c t e s t observance of the rules of operating the buildings and s t r u c t u r e s in conformity with the adopted method of using the soils as bases. The official rules and regulations (NiTU 118-54, and subsequently SN 91-60) of designing bases and foundations in p e r m a f r o s t regions were used successfully and widely in foundation p r a c ~ c e at Noril'sko The main shops of metallurgical, concentration, power, and mining enterprises of the Combine, which a r e distinguished by heavy loads, wet production p r o c e s s e s , and large r e l e a s e s of heat, were constructed on rocky soils and on talik (tabetisol) without consideration of the permanently frozen state of the foundation soils (merged I according to SN 91-60).

Noril'sk. Translated from Osnovaniya, Ftmdamenty i Mekhanika Gruntov, No. 5, pp. 29-32, September October, 1967.

352

I

-~z~oo zsoo 12600 280o z z o o12600a -2600L3200 . 2EOO . . g60O . Z6QQ . . 3ZOO . .~600 -- [ . . . . -! - _ :

_

Fig. 1. Pile foundation of large-panel house of series 1-464-m. I) Grading surface; ID surface of permafrost; H1) powdery sand; IV, V) clay soils with ice inclusions. The city of Noril'sk and the residential .villages of the mining region were constructed ~ t h preservaf~on of the permanently frozen state of the soils (method II according to SN 91-60). The construction of buildings and strucazres was accomplished in rigorous conformity with the general plans for any permanently frozen soil, including those with interbeds and lenses of underground ice. Disturbances of the ensemble of the city were not permitted. This problem could be solved for the conditions of KoriUsk only by constructing the buildings and laying the 'engineering networks in the area of the city and villages with subsequent conduction of thermotechn2cal measures recommended when constructing by method IIo The planning procedure used at NoriUsk is in full accord with the natural climatic c]mracteristics of the NoriPsk region and is confirmed by our construction practice and long (10-25 years) service of r e s t den~al and public buildings of the city. Dozens of small industrial enterprises (brick and concrete-block plants, calcining shop, regional boiler and repair plants, electric power plants, etc.) have also been built by the II method. Many of these different enterprises have been in service successfully for 10-20 y e a r s .

353

Fig. 2. Pile construction- Boring of holes and placement of piles in them. Auxiliary shops of the combine (metal-structures, casting, mechanical, charging, forging, locomotiver e p a i r shops, and others) have been constructed by the III method,which permits thawing of the p e r m a f r o s t soils of the base, with adaptation of the frames of the p r e c a s t reinforced-concrete buildings to inevitable settlements of the foundations, the maximum absolute magnitudes ofwbich are determined to be 250 ram. These shops have been built on bases composed of coarse-fragmental soils and have been in s e r v i c e for 15-25 y e a r s . During the f i r s t y e a r s of their s e r v i c e , c r a c k s were observed in the walls of the buildings, the crane rails were repeatedly straightened, and the equipment was leveled following settlement and tilting of the foundations. However, despite this,the men-tbers of the reinforced-concrete frames did not collapse. With r e g a r d to the use of the III method when constructing industrial shops of a combine we can ass e r t that construction by this method on frozen coarse-fragmental softs has completely proved itself. P r e c o n s t r u c t i o n thawing of the foundation soils (method IV according to SN 91-60) has limited use in the contTuction at Noril'sk. It was used in the construction of the underground reinforced-concrete channel of the city combined sewer and utilities system and in the construction of the head house and headframe of mine 7:ois. In the f i r s t case,thawing of the ice i~clusions was accomplished by electrical heating, and in the second case,cementation of the soil was p e r f o r m e d to a depth of 20 m in addition to thawing the icy c o a r s e - f r a g m e n t a l soils of the base [2]. These examples, as well as the favorable experience of using the method of cementation when straightening out deformed structures [8] at Noril'sk, permit us to regard preconstruction thawing (anditsnecessary subsequent strengthening) of soils as one of the efficient methods of constructing an artificial base and to r e c o m m e n d it for introduction into construction practice. During the f i r s t 25 y e a r s of construction of Noril'sk, foundations of different types were used: a) monolithic concrete column, m o r e r a r e l y reinforced-concrete column and strip footings (when constructing cellar rooms),when constructing industrial buildings by the I method; massive and, m o r e r a r e l y , r e i n f o r c e d - c o n c r e t e f r a m e - t y p e foundations f o r equipment and machines; b) monolithic concrete column footings under the r e i n f o r c e d - c o n c r e t e wall beam of the bearing wail, m o r e r a r e l y p r e c a s t concrete footings of the same type,and a low concrete pile grillage of wooden piles when constructing residential and public buildings by the II method; c) r e i n f o r c e d - c o n c r e t e shoe-type foundations under columns and,more rarely, a continuous reinforcedconcrete slab under small buildings and eonstructing industrial buildings by the III method; d) column footings when constructing by the IV method,

354

Although these types of foundations proved themselves, satisfying the requirements of stability of buildings and s t r u c t u r e s e r e c t e d on them, they also had substantial shortcomings, the main ones being that they w e r e labor-consuming and expensive. To reduce the cost and a c c e l e r a t e the p r o c e s s of constructing foundations at Noril'sk, the possibilities of using pile foundations were investigated. Reinforced-concrete pile foundations frozen into the p e r m a f r o s t soil {by the Ii method) began to be used in residential and civil construction. By the end of the 1950s this type of foundation became the most common,and completely replaced other types. Within the past decade about 400,000 m 2 of b r i c k apartment buildings, some of which were of s e r i e s 1-447, and m o r e than 150,000 m 2 of large-panel apartment buildings of s e r i e s 1-464-m havebeen constructed on pile foundations in Noril'sk. The introduction of pile foundations in Noril'sk was preceded by extensive experimental studies to develop the technology of performing pile works in p e r m a f r o s t soils and investigation of the behavior of f r o z e n - i n piles and of piles whose lower ends r e s t in rock. All this permitted a continuous improvement of the designs of pile foundations, calculations of the strength of their bases, and methods of performing substructure works. The design office of the Noril'sk Combine with participation of the Noril'sk laboratory of bases and foundations of K r a s n o y a r s k P r o m s t r o i n i i p r o e k t worked out different alternatives of pile foundations [21. The m o s t rational of them, according to which the foundations of buildings of s e r i e s 1-464-m a r e presently being constructed, is shown in Fig. 1. This version called for a single-row placement of frozen-in piles with a high type of continuous pile grillage; a high air space under the building within which are located the sewer and utility systems suspended f r o m the floor; a concrete block under the pipes for carrying away the waters arriving in the air space. Pile foundations a r e constructed in the following manner. Holes with a diameter 3-4 cm l a r g e r than the pile diameter are bored. Then the borehole is filled with drilling mud to l/3 of its depth and into it is lowered the pile (Fig. 2) fabricated at the local plant for structural elements. The pile forces out the drilling mud, which fills aH cavities in the hole. A f t e r some time the mud freezes and the pile becomes strongly frozen into the p e r m a f r o s t soil. The method of constructing pile foundations is accomplished in accord with RSN 14-62 [121. The conversion to pile foundations in combination with p r e p a r a t i o n o f the area during the s u m m e r by l a y e r - b y - l a y e r removal and t r a n s f e r of the soil by bulldozers as it falls have made it possible to achieve a high degree of indns~ialization and mechanization of fov_,~dation practice. The cost of foundations with frozen-in piles for brick buildings of s e r i e s 1-447 is almost half that of column footings, the consumption of labor for construction is less by a factor of 10. Substructure works have been accelerated by a factor of 5--6 [2]. In r e c e n t y e a r s the quite important problem of stable construction on high-temperature (above -2°C) p e r m a f r o s t soils has been successfully solved at Noril'sk. As an experiment,five large-panel houses of s e r i e s 1-464-m were built on soils with a temperature o f - 0 . 5 to--I.5°C. Their construction was accomplished in accord with special instructions which called for thermoteehnieal m e a s u r e s directed towarda steady lowering of the temperature foundation soil of the buildLugs during construction and during the f i r s t y e a r s of their service. The instructions recommend, in p a r tic,alar, artificial c o l d - a i r cooling of the supporting soil {before placing the piles) by sucking the a i r out of the bottom of the hole in o r d e r to accelerate freezing of the piles to the p e r m a f r o s t stratum of soil [6, 7]. The stability of these houses during construction and during their service o v e r the past 2-3 y e a r s has been confirmed by the results of instrumented observations, As is noted above, the main shops of the combine were constructed by the I method on rock bases. With f u r t h e r expansion and reconstruction of the combine the a r e a s with shallow bedrocks were completely used. In this connection it became particularly urgent to find rational solutions f o r the construction of deep foundations (15-25 m) on a rock base. As a result of theoretical and experimental investigations,a new method of cons~ucting deep pile foundations, based on the principle of end restraint of the pile with a rock base [13], was developed and introduced in industrial construction. The pile was restrained in a socket bored out in the rock by eementa-

355

tion of the base (Fig. 3) or by vibratory drivir~ of the pile into the rock socket previously filled with plastic concrete. A number of essential industrial objects have been constructed during the last F i v e - Y e a r Plan on foundations with a depth of up to 20 m and m o r e . Shell piles with an outside diameter of 600 mm and inside diameter of 400 mm are used when there a r e large loads on the foundations and the bedrocks a r e deep. The design load on individual shell piles reaches 400 t with a bending moment of 150 t o n - m e t e r s . The most ccmplex excavation works were previously organized to construct column footings when the rock lay at a depth of 20-25 m, and 1.5-2 y e a r s were spent for substructure works for an average size shop. With conversion to pile foundations the time of substructure works has been reduced to 5-6 months, their consumption of labor has been reduced by a factor of 5-10, and the cost has been cut in half o r m o r e . The advantages of using foundations with piles e m bedded into the rock base are not limited just to these technical and economic indexes. The construction of such foundations permits developing an efficient overall layout of the industrial complex for new constructions with a compact arrangement of all its objects at one construction site. t

~

It

N

Fig. 3. Diagram of the e ~ . . ~ c t i o n of foundations with e n d - b e a ~ pftes supported in rock. i) Boringc~l~les; 2) placement of pile and injurer into hole; 3) transportable device; I~ frozen alluvium; If) fractured bedrock with ice inclusions; HI) s t e m h e a t ~ ; IV) inJection of grout; V) e l e c t r i c a l heating.

In conclusion, it is n e c e s s a r y to point out that the NoriPsk laboratory of bases and foundations of Krasnoyarsk P r o m s troiniipreekt, in creative collaboration with the builders of the Noril Tsk combine, is continuing to improve the technology of substructure works, designs, and methods of calculating pile foundations of various configuration.

The immediate tasks of investigations a r e to solve the most urgent problems of foundation er~ineering under conditions of p e r m a f r o s t sofia, namely: improvement of the technology of performing substructure works on hightemperature p e r m a f r o s t soils when constructing by the II method; mastering of the t~mlmolo~ of constructing frozen-in clubfoot piles; investigation of the bearing capacity of frozen-in clubfoot piles under various frozen-ground conditions; investigation of the behavior of piles in the p r e s e n c e of a horizontal load under conditions of gradually thawing soft. The solution of these problems will promote the better use of progressive types of foundations in construction practice in E a s t e r n Siberia and the F a r North. LITERATURE I.

CITED

V. F. Zhukov, C o n ~ the P r o b l e m of Laying Pipelines with a Large .Release of Heat in the Nori1'sk C o a r s e - F r - ~ e n t a l Soils,Byulleten t tekhn, informatsii Noriltskogo kombinata, 1-2 (8-9) (194~.

t

3, 4.

M. V. Klm, M. A. Bitadze, B. F. Ermilov, et al., Construction of Foundations Under P e r m a f r o s t Conditions [in Russian], Gosstroiizdat (1962). M. V. Kim, Selection of Methods of Foundation Engineering Under Conditions of Noriltsk, StroitelTnaya P r o m y s h l e n n o s t t, 8 0959). M. V. Kim, Bases ~ Foundations of Civic Buildings of Noril'sk, Report at the VII Interdepartmental Conference on G e o e r ~ I o g ~ in 1956,"Reports on General Geocryology~ [in Russian], Izd. AN SSSR (1959).

.

35G

M. V. Kim and B. S. Pavlov, Measures f o r the Stability of Structures on P e r m a f r o s t , Byull. tekhn. informatsii N o r i l t s l m ~ kombinata, 1 (7) (1944).

6. 7. 8. 9. 10. 11. 12. 13.

M . V . Kim, Construction of Large-Panel Buildings on High-Temperature Permafrost Soils (from the experience of Noril'sk),Osnovaniya, fundamenty i mekhauika gruntov, 6 (1964)~ G.N. Maksimov, Artificial Air Cooling when Constructing Pile Foundations on Permafrost Soils. Collection No. 55 of NII Osnovanii "Bases and Foundations" [in Russian], Stroiizdat (1964). G.N. Maksimov, Methods of Restoring the Stability of Deformed Buildings, Byull. tekhn, informatsii Noril'skogo kombinata, 3-4, (66-67) (1967). Regulations and Technical Specifications for the Design of Natural Bases and Foundations of Buildings and Industrial Structures in P e r m a f r o s t Regions (NTU 118-54) [in Russianl (1955). Regulations and Technical Specifications for the Design of Bases and Foundations Under Permafrost Conditions (OST 90032-39) [in Russian] (1939). Technical Specifications for the Design and Bases of Foundations on Permafrost Soils (SN 91-60) [in Russian] (1960). Instructions for the Design and Construction of Pile Foundations on P e r m a f r o s t Soils (RSN 14-62) [in Russian] (1964). L Yao ~ s h t e i n , Industrial Method of Foundation Engineering in Industrial Construction in Permafrost Regions. Report at the Conference-Seminar on Exchange of Construction Experience in P e r m a f r o s t Regions of Noril'sk [in Russian], 2, Krasnoyarsk (1963).