Publisher’s version / Version de l'éditeur:
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la
première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
Technical Translation (National Research Council of Canada), 1966
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.
https://nrc-publications.canada.ca/eng/copyright
NRC Publications Archive Record / Notice des Archives des publications du CNRC : https://nrc-publications.canada.ca/eng/view/object/?id=fe4ff553-9fd6-4e0f-b72b-2c212df64d64 https://publications-cnrc.canada.ca/fra/voir/objet/?id=fe4ff553-9fd6-4e0f-b72b-2c212df64d64
NRC Publications Archive
Archives des publications du CNRC
For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.
https://doi.org/10.4224/20375925
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Specific features of the maintenance of structures in permafrost conditions
Dement'ev, A. I.; National Research Council of Canada. Division of Building Research
PREFACE
T h i s t r a n s l a t i o n i s t h e s i x t h from t h e Russian permafrost
p u b l i c a t i o n " ~ r i n c i p l e s of ~ e o c r y o l o g y " , P a r t I1 ( ~ n g i n e e r i n g Qeocry- :logy). The f i r s t t r a n s l a t i o n i n t h i s group was Chapter I e n t i t l e d
P r i n c i p l e Aspects of Engineering Geocryology (permafrost S t u d i e s ) " by N . I . Saltykov (TT-1215). The second was Chapter VII a articular
Aspects of Mining i n Thick ~ e r m a f r o s t " by V.P. Bakakin (TT-1217). The t h i r d was Chapter I1 "Deformation of S t r u c t u r e s R e s u l t i n g from t h e Processes of Freezing and Thawing" by A . I . Dementlev (TT-1219). The f o u r t h was Chapter V I I I " ~ e d s f o r Roads and ~ i r f i e l d s ' by
G.V. Porkhaev and A.V. Sadovskii (TT-1220). The f i f t h was Chapter I X "underground U t i l i t y ~ i n e s " by G .V. Porkhaev (TT-1221) ,
T h i s t r a n s l a t i o n of Chapter X I by A . I . Dementtev d i s c u s s e s t h e p a r t i c u l a r problems of m a i n t a i n i n g s t r u c t u r e s i n permafrost a r e a s . Problems a s s o c i a t e d w i t h keeping t h e s i t e i n good c o n d i t i o n a r e p r e - s e n t e d f i r s t . T h i s i s followed by t h r e e s e c t i o n s each c o n s i d e r i n g a p a r t i c u l a r c o n s t r u c t i o n method and a s s o c i a t e d maintenance requirements. The f i r s t i s concerned w i t h t h e c o n s t r u c t i o n method used t o p r e s e r v e t h e permafrost c o n d i t i o n i n t h e f o u n d a t i o n s o i l s , t h e second a l l o w s t h e permafrost t o thaw, and t h e t h i r d d i s r e g a r d s t h e permafrost be- cause it does n o t a f f e c t t h e s t r u c t u r e . The c h a p t e r concludes w i t h i n s t r u c t i o n s f o r r e l e a s i n g t h e completed s t r u c t u r e t o t h e occupants, and s u g g e s t i o n s f o r long-term o b s e r v a t i o n s on performance.
T h i s c h a p t e r was t r a n s l a t e d by Associated T e c h n i c a l S e r v i c e s I n c . , E a s t Orange, New J e r s e y , U.S.A., f o r t h e U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, N.H., U.S.A. The Divi- s i o n of B u i l d i n g Research i s g r a t e f u l t o t h i s agency f o r p e r m i t t i n g t h e N a t i o n a l Research Council t o i s s u e t h i s t r a n s l a t i o n i n i t s Tech- n i c a l T r a n s l a t i o n s s e r i e s , and t o Dr. R.J.E. Brown of t h i s D i v i s i o n who checked t h e t r a n s l a t i o n .
Ottawa R.F. Legget
NATIONAL RESEARCH COUNCIL OF CANADA Technical Translation 1232
Title : Specifia features of the maintenance of structures in
permafrost conditions
soben en nos ti
ekspluatatsionnogo soderzhaniya sooruzheniiv
usloviyalch rasprostranenlya mnogoletnemerzlykh gruntov)Author : A.I. Dementtev
Reference: Principles of geocryology (permafrost studies), Part 11,
Engineering geocryology, Chapter XI. Academy of Scienaes
of the U.S.S.R. Moscow 1959. p.285-297
(~snovy geokriologli (merzlotovedeniya), Chastt vtoraya,
Inzhenernaya geokriologiya, olava XI. Akademiya Nauk
SPECIFIC FEATURES OF THE MAINTENANCE OF
STRUCTURES IN PERMAFROST CONDITIONS*
Introduction. 1. Special features of maintenance of a built-up area. 2. Maintenance of structures erected with preservation of fro- zen state of the foundation soils.
3.
Maintenance of structures erec- ted without preservation of the foundation soils in the frozen state.4.
Maintenance of structures erected without taking into account changes in aggregate state of the foundation soils.5.
Special fea- tures of turning over the structures for operation.6.
Organization of long-term observations of structures erected on perennially frozen ground.
Introduction
The consideration of the stability and condition of any structure erected on perennially frozen ground, and of the interaction between the structure and the ground, should take into account three periods:
(a) period of erection of the structure;
(b) initial period of use and maintenance of structure, when it adjusts to the new environment and sometimes modifies it;
(c) second'period of use and mainterlance of structure, when underlying ground has already become stabilized to a certain degree and the structure has achieved an equilibrium with its environment.
The most complicated and important is the initial period of use and maintenance of the structure. Although it is considerably shorter than the second period, it requires closer attention and sometimes active interference in the process of interaction between the structure and environment in which it was built.
The stability and normal operation of engineering structures in perma- frost areas depend not only on the correctness of design but also on the qual- ity of construction work and on the observance of maintenance rules during use.
Requirements concerning design and construction of structures have been investigated to the greatest extent and are the main subject of discussion in the foregoing chapters of this volume. This chapter is devoted to the impor- tant but not sufficiently elaborated problem of the maintenance of structures during use.
*
Terminology corrected to conform to that used in other chapters of this publicat ion.-
Ed. (~ussian)The special features of the maintenance of structures erected on perennially frozen ground, as compared with the maintenance of structures
erected in regions without permafrost, are principally determined by the ther- mal interaction between structure and the ground. A prolonged thermal inter- action may cause substantial changes in engineering properties of soils and may lead to phenomena that had never occurred on the construction site before the structure was erected.
It often happens that structures undergo deformation during use and expensive repairs and renovation work are needed; sometimes structures fail completely. This results in considerable losses to the national economy (Chapter 11). Many of these deformations might be avoided by compliance with elementary rules of maintenance during use.
The questions of use and maintenance should be taken into account from the very beginning of the construction work. First of all, it is necessary to watch that perennially frozen ground does not thaw during construction, if this was not provided for In the design. Thawing may result from disturbance of the vegetative cover on the construction site, from wetting of excavations, and from the operation of temporary structures, such as concrete plants, con- crete and mortar mixing installations, temporary communications, etc. There- fore, heat-generating temporary installations should be located far away from principal structures and should be under continuous observation. At times, construction work reveals that exploration (survey) data do not tally with the actual permafrost conditions.
Acknowledging that correct use and maintenance is of great importance for ensuring the stability of structures, the following three principles should be kept in mind.
1. Maintenance of the structure is an important link in the chain of successive stages involved in the erection and use of the structure: design, construction and maintenance.
2. Incorrect use and maintenance may lead to destruction of the structure, even when it was well designed and soundly constructed.
3.
At times, special methods of maintenance make it possible to eliminate errors made during design and construction work.Of these three principles, the first one is the most important, and we shall treat it in greater detail. First of all, it should be noted that the maintenance of structures is closely related to the natural conditions of the region. The methods of maintenance of a structure should not be planned with- out taking into account the local natural conditions, geological conditions, and thermal regime of perennially frozen ground, and the characteristics of the given construction site and given structure. These factors predetermine
t h e c o n d i t i o n s of maintenance and c r e a t e t h e s i t u a t i o n i n which t h e g i v e n s t r u c t u r e o p e r a t e s .
A s s t a t e d i n Chapter I , methods of m a i n t a i n i n g s t r u c t u r e s must be c l o s e l y r e l a t e d t o and f u l l y dependent on t h e method used t o e n s u r e t h e s t a b i l i t y of t h e s e s t r u c t u r e s . For example, i f a s t r u c t u r e was e r e c t e d w i t h p r e s e r v a t i o n of t h e f r o z e n s t a t e o f t h e b e a r i n g medium, t h e n i t s maintenance must be such t h a t t h e foundation s o i l s w i l l not thaw a s l o n g a s t h e s t r u c t u r e i s u s e d . I f
a s t r u c t u r e was e r e c t e d w i t h prethawing of t h e ground, o r was b u i l t on a t a l i k , t h e n f r e e z i n g of t h e ground b e n e a t h t h e s t r u c t u r e must not be p e r m i t t e d , be- cause t h i s would lead t o i t s deformation.
Maintenance measures a p p l i e d t o keep a s t r u c t u r e i n good c o n d i t i o n may
d i f f e r i n r e l a t i o n t o t h e i r purpose and amount of e f f o r t expended. The pur- pose of t h e s e measures depends on t h e method of c o n s t r u c t i o n . The e f f o r t expended i s determined by t h e i n t e n s i t y and s e v e r i t y of t h e f a c t o r s t h a t have t o be combatted i n o r d e r t o s e c u r e a sound c o n d i t i o n of t h e s t r u c t u r e . If a s t r u c t u r e i s b u i l t by t h e method of r e t a i n i n g t h e f r o z e n s t a t e of t h e b e a r i n g medium, i t i s n o t always easy t o p r e s e r v e t h i s s t a t e . Under c o n d i t i o n s of low
a i r t e m p e r a t u r e s and p e r e n n i a l l y f r o z e n ground, f o r example, on Taimyr, it may be s u f f i c i e n t t o p r e v e n t heavy accumulations of snow around s t r u c t u r e s . I n Vorkuta, it would a l s o be n e c e s s a r y t o m a i n t a i n i n good o r d e r c o o l i n g p l a n t s o p e r a t i n g on t h e p r i n c i p l e of u t i l i z i n g t h e w i n t e r c o l d . It i s p o s s i b l e t h a t i n C h i t a o r i n t h e Petrovsk-Transbaikal r e g i o n p r e s e r v a t i o n of t h e b e a r i n g medium i n t h e f r o z e n s t a t e would i n v o l v e m a i n t a i n i n g a c o o l i n g u n i t o r f o r c e d v e n t i l a t i o n . The same h o l d s t r u e where a s t r u c t u r e was e r e c t e d a c c o r d i n g t o a d e s i g n t a k i n g i n t o account t h e adjustment of elements of t h i s s t r u c t u r e t o d i f f e r e n t i a l s e t t l e m e n t of t h e b e a r i n g medium a s i t thaws i n t h e c o u r s e of t i m e . The main f e a t u r e of t h e maintenance of such a s t r u c t u r e l i e s i n con- t r o l l i n g t h e adjustment of i t s elements t o s e t t l e m e n t , because a t p r e s e n t t h i s adjustment does n o t proceed a u t o m a t i c a l l y . T h i s i m p l i e s t h e f o l l o w i n g :
(1) s y s t e m a t i c o b s e r v a t i o n t o determine whether t h e a c t u a l s e t t l e m e n t w i t h
time a g r e e s w i t h t h a t provided f o r i n t h e d e s i g n ; ( 2 ) r e g u l a t i o n of ground thawing; and ( 3 ) mechanical r e g u l a t i o n of s e t t l e m e n t of i n d i v i d u a l p a r t s of t h e b u i l d i n g . The degree of complexity involved i n c o n t r o l l i n g t h e adjustment of t h e s t r u c t u r e t o s e t t l e m e n t depends on t h e p r o p e r t i e s of t h e ground a t t h e s i t e . When s e t t l e m e n t i s extreme and h i g h l y d i f f e r e n t i a l , amounting, f o r ex- ample, t o 100 o r 150 ma p e r y e a r , and t h e b u i l d i n g has a complex d e s i g n ( f o r example, a feame s t r u c t u r e on a continuous f o o t i n g ) and occupies a l a r g e a r e a , t h e n t h e r e g u l a t i a n should be performed once o r t w i c e a month. When s e t t l e - ment i s n e g l i g i b l e , f o r example 5 o r 10 mm p e r y e a r , and t h e b u i l d i n g i s sup- p o r t e d by a continuous r e i n f o r c e d - c o n c r e t e f o u n d a t i o n s l a b , t h e n no r e g u l a t i o n
may be needed. We are discussing here the normal use and maintenance of a structure correctly designed and built, taking into account the local pecu- liarities of the site and in compliance with requirements of engineering geocryology
.
In view of the fact that, on the one hand, maintenance measures for structures erected on permafrost have not as yet been sufficiently studied, and, on the other hand, a great diversity of types of engineering structures exists, we shall consider in this chapter mainly the maintenance of industrial and residential buildings, which represent the most common and the best stud- ied type of engineering structures. However, the considerations presented here may be used to a certain degree to clarify maintenance features of other
structures, such as hydroelectric plants, mines and airports.
1. Special Features of Maintenance of a Built-up Area
Of utmost importance in the normal operation of a structure erected on frozen ground is the systematic care and efficient maintenance of the built-up area (site).
Unlike the maintenance of a built-up area in normal conditions, which involves only the diversion of surface water, snow removal and preservation of graded surfaces and pavements, the maintenance of a built-up area in perma- frost conditions requires, in addition, the preservation of the thermal regime and the state of the ground as foreseen by the design. This should be done not only at the location occupied by a structure but throughout the built-up area, because groundwater circulating there may substantially influence the heat exchange beneath the individual structures. Therefore, it should be kept in mind that when structures with different thermal regimes are erected on ad- joining sites, changes in the hydrogeological and thermal conditions of these sites are possible, and often inevitable; and these, in turn, influence the stability of the structures.
The following factors may influence the formation of the thermal regime and state of the perennially frozen bearing medium beneath the structure:
(1) Liberation of heat from the structure itself, both in cases of normal maintenance and in connection with disturbance of normal technological
prooesses;
(2) liberation of heat from water mains, sewer systems, heating pipes, etc., especially in cases of leakage;
(3)
snow cover, especially large local accumulations of snow;(4)
presence of ground and surface water;L i b e r a t i o n of h e a t from t h e s t r u c t u r e i s a dominant f a c t o r i n t h e
formation of t h e t h e r m a l regime o f t h e ground beneath t h e s t r u c t u r e . Depend- i n g on t h e magnitude of t h e h e a t p r o d u c t i o n o r h e a t a b s o r p t i o n , which depends t o a l a r g e degree on t h e methods of maintenance of t h e s t r u c t u r e and on t h e compliance w i t h e s t a b l i s h e d requirements, t h e s t r u c t u r e may c o n t r i b u t e e i t h e r t o t h e c o o l i n g o r t o t h e thawing of p e r e n n i a l l y f r o z e n ground beneath i t . It
may be mentioned, a s a n example, t h a t i n p r a c t i c e i n d u s t r i a l waste w a t e r s , even t h o s e having a h i g h temperature, a r e o f t e n allowed t o d i s c h a r g e d i r e c t l y i n t o t h e ground. There a r e many recorded c a s e s where b u i l d i n g s c o l l a p s e d com- p l e t e l y because of badly organized d i s c h a r g e of warm water, which caused thaw- i n g and s e t t l i n g of t h e f r o z e n ground beneath them.
A sudden c o o l i n g of t h e ground beneath t h e s t r u c t u r e , n o t a n t i c i p a t e d by t h e d e s i g n , such a s a n i n t e r r u p t i o n i n h e a t i n g of b u i l d i n g s e r e c t e d on n a t u r a l o r a r t i f i c i a l t a l i k s , may r e s u l t i n f r e e z i n g of t h e ground, heaving, and d e f o r - mations of t h e s t r u c t u r e .
The main r u l e co b e observed i n t h e maintenance of s t r u c t u r e s e r e c t e d i n permafrost r e g i o n s i s s t r i c t p r e s e r v a t i o n of t h e t h e r m a l regime a n t i c i p a t e d by t h e d e s i g n .
L i b e r a t i o n of h e a t from water, sewage, h e a t i n g and o t h e r p i p e l i n e s . Underground c o n d u i t s a r e a c o n s t a n t source of h e a t and have a c o n s i d e r a b l e
e f f e c t on t h e temperature of t h e surrounding ground. E s p e c i a l l y l a r g e changes a r e caused by underground steam o r h o t water p i p e s . The h e a t i n g e f f e c t of t h e s e p i p e s i s u s u a l l y i n c r e a s e d by t h e f a c t t h a t groundwater c i r c u l a t i n g around them becomes warm and i s transformed i n t o an independent h e a t c a r r i e r . There were c a s e s observed where groundwater completely f i l l e d t h e b u r i e d boxes i n which h e a t i n g p i p e s were l a i d , which r e s u l t e d i n a very r a p i d growth of t h e zone of thawed f r o z e n ground. Thawing of t h e ground may l e a d t o i t s s e t t l e - ment and consequently t o t h e s e t t l e m e n t of p i p e s . For example, a t one of t h e i n d u s t r i a l e n t e r p r i s e s n e a r C h i t a , d u r i n g seven y e a r s ' o p e r a t i o n of t h e h e a t - i n g p i p e l i n e , i t s s e t t l e m e n t i n some s e c t i o n s reached 1 m. Normal o p e r a t i o n of t h i s p i p e l i n e was r e s t o r e d a f t e r t h e p i p e s were i n s t a l l e d i n boxes on t h e ground s u r f a c e
.
&Frozen s o i l s a r e i n t e n s i v e l y heated and consequently thaw i n t h e v i c i n i t y of p i p e s used f o r t h e d i s p o s a l of h o t waste water from i n d u s t r i a l p r o c e s s e s and from b a t h houses. Water p i p e s and c i t y sewer p i p e s , when i n good condi- t i o n , a l s o have a h e a t i n g e f f e c t on f r o z e n ground, b u t t h i s e f f e c t i s n e g l i g i - b l e and does not l e a d t o t h e deformation of a d j a c e n t s t r u c t u r e s . The h e a t i n g of t h e ground i n c r e a s e s markedly when p i p e s a r e i n improper c o n d i t i o n and l i q u i d l e a k s i n t o t h e ground.
A continuous c o n t r o l should be e x e r c i s e d over t h e o p e r a t i o n and s t a t e of water and sewer p i p e s , and e s p e c i a l l y of h e a t i n g p i p e l i n e s l o c a t e d i n t h e a r e a a d j a c e n t t o t h e s t r u c t u r e s . A l l t h e g , a l l e r i e s ( t u n n e l s ) , boxes, manholes and s o on, a s w e l l a s j o i n t s and i n s u l a t i o n of p i p e l i n e s , should be s u b j e c t e d t o s y s t e m a t i c i n s p e c t i o n .
Any leakage from water, sewer, o r h e a t i n g p i p e s , however n e g l i g i b l e i t may be, should be considered a s damage, and should be e l i m i n a t e d immediately. When water supply and h e a t i n g networks a r e l a i d above t h e ground s u r f a c e , l e v e l l i n g of p i p e s should be performed a n n u a l l y i n t h e summer, and, i f g r a d e s have changed, t h e y should be brought i n t o l i n e w i t h t h e d e s i g n . When p i p e s a r e l a i d i n d i t c h e s , c a r e should be t a k e n t o prevent thawing o f t h e ground a t t h e bottom and s i d e s of t h e d i t c h d u r i n g t h e summer, beyond t h e l i m i t s of t h e a r t i f i c i a l b a s e . I n w i n t e r t h e thawed ground should be completely f r o z e n by means of v e n t i l a t i o n by o u t s i d e a i r .
Heat i n s u l a t i o n of water and sewer p i p e s i n d i t c h e s and a i r s p a c e s below t h e f l o o r s i s mandatory. Those i n t h e a i r s p a c e s should be r e g u l a r l y inspec- t e d . To p r o t e c t water and sewer systems from f r e e z i n g , a l l measures s p e c i f i e d i n t h e d e s i g n should be c a r r i e d o u t , i n c l u d i n g h e a t i n g of vrater t o t h e temp- e r a t u r e e s t a b l i s h e d by d e s i g n computations and d i s p o s a l of warm waste water
(from b a t h houses, l a u n d r i e s , e t c . ) i n t o t h e sewer system. The temperature of water i n wafver supply systems should be s y s t e m a t i c a l l y measured a t t e r m i n a l p o i n t s of t h e d i s t r i b u t i o n system. The temperature of waste water should be measured a t p l a c e s of i t s d i s c h a r g e on t h e ground s u r f a c e .
The water flowing from h y d r a n t s l o c a t e d n e a r b u i l d i n g s and i n t h e s t r e e t s c e r t a i n l y should be d i v e r t e d i n t o t h e sewer system. I n e x c e p t i o n a l c a s e s , i n s e t t l e m e n t s l o c a t e d f a r from l a r g e r e s i d e n t i a l and i n d u s t r i a l b u i l d i n g s , i t i s
p e r m i s s i b l e t o d i v e r t water t o low-lying ground i n a r e a a n o t b u i l t - u p a t p r e s - e n t and not t o be b u i l t - u p i n t h e f u t u r e .
When a h e a t i n g system i s b e i n g emptied, t h e w a t e r should a l s o be d i s - charged e i t h e r t o t h e sewer system o r t o low-lying a r e a s l o c a t e d beyond t h e b u i l t - u p a r e a a t a d i s t a n c e no c l o s e r thanX>m from b u i l d i n g s .
Snow cover and l o c a l snow accumulations. It i s known t h a t l o c a l snow accumulations may a c t a s s o u r c e s of h e a t and s u b s t a n t i a l l y a f f e c t t h e thermal regime of t h e ground.
The h e a t i n g e f f e c t of snow accumulations may be e s p e c i a l l y l a r g e i n c a s e s where t h e p e r i m e t e r w a l l s of a s t r u c t u r e a r e n o t provided w i t h a i r v e n t s ; and a c c o r d i n g t o t h e d e s i g n , c o o l i n g of t h e a i r space between t h e f l o o r and t h e ground should proceed o n l y by h e a t conduction from t h e p e r i m e t e r w a l l . T h i s q u i t e o f t e n s u f f i c e s i n r e g i o n s w i t h low a i r t e m p e r a t u r e s i n t h e w i n t e r . How- e v e r , when t h e p e r i m e t e r w a l l s u r f a c e i s covered by snow, t h e a i r space below t h e f l o o r i s warmed and t h e f r o z e n s t a t e of t h e f o u n d a t i o n s a i l b e n e a t h t h i s
s t r u c t u r e , planned f o r i n t h e d e s i g n , may be d i s t u r b e d ,
Snow accumulations may have a n a d v e r s e e f f e c t on t h e o p e r a t i o n of t h e v e n t i l a t e d a i r space between t h e f l o o r and t h e ground and on o t h e r c o o l i n g d e v i c e s . If a i r v e n t s i n p e r i m e t e r w a l l s e n c l o s i n g t h e above a i r apace, o r t h e i n l e t s o r o u t l e t s of o t h e r c o o l i n g i n s t a l l a t i o n s , a r e blocked by snow, t h e i n f l u x of o u t s i d e cold a i r through t h e s e openings w i l l be reduced. Con- s e q u e n t l y , t h e e f f e c t of t h e c o o l i n g i n s t a l l a t i o n w i l l be d e c r e a s e d . A pro- longed r e d u c t i o n i n t h e e f f i c i e n c y of c o o l i n g i n s t a l l a t i o n s may l e a d t o thaw- i n g of t h e ground and consequently t o deformation of t h e s t r u c t u r e . Therefore, snow accumulations should not be p e r m i t t e d i n p l a c e s n e a r t h e v e n t s of v e n t i - l a t e d a i r spaces below f l o o r s , o r n e a r o u t s i d e openings of f o r c e d v e n t i l a t i o n c o o l i n g i n s t a l l a t i o n s , a i r v e n t s and g r a t i n g s . They should be r e g u l a r l y i n s - pected and c l e a r e d a f t e r each snow storm i n w i n t e r .
Ground and s u r f a c e water. Having a h i g h h e a t c o n t e n t , ground and s u r f a c e water r e p r e s e n t s an important h e a t i n g f a c t o r i n t h e e s t a b l i s h m e n t of t h e t h e r - mal regime of t h e ground. Any change i n t h e regime of t h e s e w a t e r s may l e a d t o a change i n t h e thermal regime of t h e ground. Consequently, t h e r e g u l a t i o n of s u r f a c e and underground water i s a n e c e s s a r y measure i n t h e maintenance of s t r u c t u r e s .
Proper a t t e n t i o n should be devoted t o keeping t h e decking* i n good o r d e r and t o d i v e r t i n g ground water from s t r u c t u r e s . No accumulation o r s t a g n a t i o n of groundwater should be p e r m i t t e d e i t h e r around t h e s t r u c t u r e o r i n t h e en- t i r e b u i l t - u p a r e a . Haphazard d i s c h a r g e i n t o t h e ground of waste w a t e r s from i n d u s t r i a l p r o c e s s e s , l a u n d r i e s , and b a t h houses should be f o r b i d d e n . T h i s water should be d i v e r t e d t o a r e a s l y i n g s u f f i c i e n t l y f a r from s t r u c t u r e s . P a r t i c u l a r c a r e should be t a k e n t o keep t h e d r a i n a g e network i n good r e p a i r .
The o p e r a t i o n of closed d r a i n s may be c o n t r o l l e d most r e l i a b l y by
measuring t h e ground water flow i n them. When t h e flow d e c r e a s e s s h a r p l y o r s t o p s completely, t h e damaged s e c t i o n of t h e d r a i n a g e system should be found by checking t h e water l e v e l i n t h e manholes. A d i s t u r b a n c e of normal condi- t i o n s i n a d j a c e n t manholes i n d i c a t e s t h a t t h e d r a i n a g e system i s plugged and
i t s c a p a c i t y i s d e c r e a s e d . A damaged s e c t i o n , l o c a t e d i n t h e above-mentioned manner, must be immediately r e p a i r e d .
Roads and s t r e e t s . Changes introduced i n t o t h e n a t u r a l thermal regime of t h e ground by l a y i n g o u t r o a d s and s t r e e t s a r e u s u a l l y r e v e a l e d by a n i n c r e a s e i n h e a t exchange. I n summer t h e d e p t h of thaw i s i n c r e a s e d beneath t h e roads; i n w i n t e r t h e c o o l i n g i n c r e a s e s . I n t e n s i v e c o o l i n g of t h e ground under r o a d s
*
Decking (otmostok) i s a ground cover of wood o r o t h e r m a t e r i a l extending outwards from t h e f o u n d a t i o n .i n w i n t e r s w i t h l i t t l e snow and low a i r t e m p e r a t u r e s may l e a d t o heaving of road beds and a d j a c e n t s t r u c t u r e s , and a l s o t o f r e e z i n g of w a t e r and sewer
systems, e s p e c i a l l y n e a r manholes.
Roads c r o s s i n g a b u i l t - u p a r e a and a d j o i n i n g d i t c h e s should be i n s p e c t e d , c l e a n e d , and k e p t i n good o r d e r . They should o p e r a t e p r o p e r l y d u r i n g t h e en- t i r e p e r i o d of u s e . When t h e snow b e g i n s t o m e l t , i t should be removed from d i t c h e s .
2 . Maintenance of S t r u c t u r e s E r e c t e d With
P r e s e r v a t i o n of t h e Frozen S t a t e of t h e Foundation S o i l s
The main r e q u i s i t e f o r a s t a b l e s t a t e of s t r u c t u r e s e r e c t e d by t h i s
method i s t h a t t h e f o u n d a t i o n s o i l s be kept f r o z e n d u r i n g t h e e n t i r e period of occupancy. The f r o z e n s t a t e of t h e ground should be preserved whereby h e a t l o s s e s from t h e s t r u c t u r e a r e minimal and t h e i n s i d e thermal regime f u l f i l l s t h e purpose of t h e s t r u c t u r e .
The f o l l o w i n g should be done i n o r d e r t o meet t h e s e r e q u i r e m e n t s : c o o l i n g i n s t a l l a t i o n s , v e n t i l a t i o n a p p a r a t u s , and t h e a i r space below t h e f l o o r should be maintained i n good o r d e r , and t h e i r normal o p e r a t i o n should proceed smooth- l y a s a n t i c i p a t e d by t h e d e s i g n computations and t h e d e s i g n of t h e s t r u c t u r e s . I n s t r u c t i o n s concerning t h e programme f o r r e f r i g e r a t i o n i n s t a l l a t i o n s and
t h e i r r e g u l a t i o n ( s t a r t i n g and s t o p p i n g of t h e i r o p e r a t i o n i n w i n t e r and sum- mer, t e m p e r a t u r e of i n f l o w i n g a i r , v e l o c i t y of a i r movement, e t c . ) should be g i v e n t o g e t h e r w i t h o t h e r i n s t r u c t i o n s on t h e maintenance of t h e s t r u c t u r e a t t h e t i m e when t h i s s t r u c t u r e i s b e i n g turned over f o r c p e r a t i o n . However, i f n e c e s s a r y , t N s programme may be ad J u s t e d a c c o r d i n g t o t h e r e s u l t s of o p e r a t i o n .
I n c a s e s where t h e f r o z e n ground a t t h e base of a s t r u c t u r e may be
e s p e c i a l l y s u s c e p t i b l e t o thawing, f o r example, under b r i c k - k i l n s , m e t a l l u r l - c a l f u r n a c e s , glass-works and t h e l i k e , and p a r t i c u l a r l y i n c a s e s where t h e danger of such thawing from i n d u s t r i a l p r o c e s s e s i n a s t r u c t u r e i s n o t f u l l y e l i m i n a t e d i n s p i t e of a l l measures t a k e n , r e g u l a r o b s e r v a t i o n s of t h e temp- e r a t u r e of t h e p e r e n n i a l l y f r o z e n ground should be o r g a n i z e d , a s w e l l a s ob- s e r v a t i o n s of t h e permafrost t a b l e . A schedule of t h e s e o b s e r v a t i o n s i s e s t a - b l i s h e d i n each i n d i v i d u a l c a s e depending on t h e n a t u r e of t h e s t r u c t u r e and on l o c a l n a t u r a l c o n d i t i o n s .
If o b s e r v a t i o n s r e v e a l d i s t u r b a n c e of t h e d e s i g n - s p e c i f i e d thermal regime of t h e permafrost and t h e permafrost t a b l e , measures f o r r e s t o r a t i o n of t h e u n d i s t u r b e d c o n d i t i o n s should be t a k e n immediately. T h i s may be accomplished by d e c r e a s i n g t h e amount of h e a t flow i n t o t h e f o u n d a t i o n s o i l s and may be implemented by v a r i o u s means, depending on t h e d e s i g n of t h e s t r u c t u r e . I n s t r u c t u r e s having t h e u s u a l v e n t i l a t e d a i r space below t h e f l o o r , It i s
expedient d u r i n g t h e w a r m months t o i n c r e a s e t h e h e a t I n s u l a t i o n of t h e ground s u r f a c e i n t h e a i r space, t h e s u r f a c e of t h e decking, and i n some c a s e s t h e p e r i m e t e r w a l l . I f t h e a i r space below t h e f l o o r i s being cooled by n a t u r a l o r f o r c e d v e n t i l a t i o n , i t i s recommended t h a t t h e a i r c i r c u l a t i o n be i n c r e a s e d i n w i n t e r and stopped when t h e temperature of t h e o u t s i d e a i r approaches t h e mean annual temperature of t h e p e r m a f r o s t . I n warm months, t h e h e a t i n s u l a - t i o n of t h e ground i n t h e a i r space should be guaranteed a s i n d i c a t e d above.
If c o o l i n g of t h e a i r space below t h e f l o o r r e s u l t s i n e x c e s s i v e h e a t l o s s e s of t h e s t r u c t u r e and i f t h e s e a r e caused by r e a s o n s o t h e r t h a n i n s u f f i - c i e n t h e a t i n s u l a t i o n of t h e f l o o r above t h e a i r space, t h e soundness of t h e accepted c o o l i n g programme should be checked and t h e e f f e c t i v e n e s s of c o o l i n g i n s t a l l a t i o n s d e c r e a s e d . T h i s may be achieved In t h e w i n t e r by c l o s i n g t h e v e n t s f o r t h e v e n t i l a t i o n of t h e a i r space f o r c e r t a i n p e r i o d s of t i m e , and i n a d d i t i o n by some i n s u l a t i o n of t h e p e r i m e t e r w a l l . A t t h e same time, t o avoid a n extreme i n c r e a s e i n t h e temperature of t h e cooled a i r space below t h e f l o o r and thawing of t h e u n d e r l y i n g p e r m a f r o s t , it i s recommended, w h i l e e x e c u t i n g t 9 e above measure, t h a t o b s e r v a t i o n s be made of t h e ground temperature and permafrost t a b l e .
The f l o o r s above t h e a i r space i n i n d u s t r i a l and r e s i d e n t i a l s t r u c t u r e s should be made a i r t i g h t and i n s u l a t e d t o such a degree t o a s s u r e normal condi- t i o n s of u s e on t h e ground f l o o r above t h e a i r space d u r i n g t h e e n t i r e w i n t e r . I n t h e p r o c e s s of i n s u l a t i n g , c l o s e a t t e n t i o n should be g i v e n t o t i g h t n e s s , e s p e c i a l l y i n p l a c e s where t h e f l o o r meets t h e w a l l s , because t h e presence of c r a c k s , even i n c a s e s of good h e a t i n s u l a t i o n , w i l l r e s u l t i n a flow of cold
a i r from t h e space below t h e f l o o r i n t o t h e b u i l d i n g . To p r e v e n t water from p e n e t r a t i n g i n t o t h e a i r space, f l o o r s of l a u n d r i e s , t o i l e t s and bathrooms should be made impermeable, a s w e l l a s t h o s e of p l a n t s where p r o c e s s e s r e q u i r e t h e u s e of l i q u i d s . Use of t h e v e n t i l a t e d a i r space a s a storeroom, dump, f u e l s t o r e , e t c . , should be f o r b i d d e n .
I n o r d e r t o d e t e c t s i g n s of deformation as e a r l y a s p o s s i b l e and t o prevent t h e i r development t o a degree endangering t h e s a f e t y o r normal opera- t i o n of s t r u c t u r e s , t h e l a t t e r should be r e g u l a r l y i n s p e c t e d . Schedules of such i n s p e c t i o n s a r e e s t a b l i s h e d i n each i n d i v i d u a l c a s e depending on t h e na- t u r e o f t h e s t r u c t u r e and l o c a l permafrost c o n d i t i o n s .
B u i l d i n g s and s t r u c t u r e s c h a r a c t e r i z e d by h i g h h e a t flow, such a s t h o s e c o n t a i n i n g a l a r g e network of h e a t - b e a r i n g p i p e s ( e l e c t r i c power p l a n t s , b o i l - e r p l a n t s , b a t h houses, l a u n d r i e s , d i s t r i c t h e a t i n g p l a n t s , e t c . ) should be i n s p e c t e d more o f t e n t h a n o r d i n a r y r e s i d e n t i a l and i n d u s t r i a l s t r u c t u r e s .
3.
Maintenance of Structures Erected Without Preservation of the Foundation Soils in the fiozen StateIt is known that when structures are built on perennially frozen ground without measures taken to keep the ground in the frozen state, two methods are used to secure the stability of the structures:
(1) designing the structure to adjust to gradual thawing of the ground under it during occupancy;
(2) preconstruction thawing of the foundation soils.
Each of these methods necessitates specific ways of maintaining the structures.
blaintenance of structures erected by the method of adjusting to a gradual
thaw in^ of the foundation soils. The simplicity or complexity of maintaining
structures resting on thawing foundation soils is closely related to the actu- al unevenness of thawing and the actual settlement rate of the soils and to the degree to which they agree with the predicted settlements accepted in the design.
The maintenance of structures under these conditions should be based on regular observations of the following factors: the external state of the struc- tures, the inside thermal regime, ground temperature, thawing regime (position of the permafrost table), and the displacement of structural elements.
If the actual thawing of frozen ground beneath the structure and the rate of its settlement coincide with the assumptions accepted in the design, and the structure was designed and constructed correctly, then it should be stable and its maintenance will involve only an accurate compliance with rules provided by the design. These rules may provide for a systematic heating of the ground and a systematic mechanical adjustment of the po~ition of certain elements of the structure.
Electric heaters specified in the design or pipes carrying steam or hot water may be used to heat the ground. The regulation of thawing in the main- tenance of the structure should be accompanied by control observations of the depth of thaw and settlement of the structure.
The task of technical supervision is the timely and careful operation of the above-mentioned heating installations, because overheating of the ground may result in undesirable settlement. The mechanical adjustnent of certain
supporting members of structures, such as crane tracks, girders, and others, as well as that of supporting parts of engines, is executed by means of speci- ally provided jacks, wedges and other devices similar to those used in the maintenance of structures erected on loess soils.
t h e n t h e s t r u c t u r e w i l l be under more favourable c o n d i t i o n s than t h o s e envisaged by t h e d e s i g n . I f , however, thawlng and s e t t l e m e n t proceed more r a p i d l y o r i n a d i f f e r e n t manner t h a n was a n t i c i p a t e d I n t h e design, addi- t i o n a l measures may be needed i n o r d e r t o r e t a i n t h e s t a b i l i t y and s a f e t y of t h e s t r u c t u r e .
Cracks and o t h e r deformation i n t h e elements of t h e s t r u c t u r e s may s e r v e a s e x t e r n a l i n d i c a t i o n s of a d e v i a t i o n of t h e a c t u a l thawing from t h a t a n t i c i - pated i n t h e d e s i g n . I f such i n d i c a t i o n s appear, then temperature measure- ments, l e v e l l i n g and o t h e r o b s e r v a t i o n s should be c a r r i e d o u t more f r e q u e n t l y and i n g r e a t e r d e t a i l .
I f t h e d e p t h of thaw and magnitude of s e t t l e m e n t of t h e s t r u c t u r e
d i s a g r e e considerably with t h e v a l u e s assumed i n t h e design, and a l s o i f t h e magnitude of s e t t l e m e n t of t h e s t r u c t u r e appears dangerous, i t may be neces-
s a r y t o r e g u l a t e f u r t h e r thawing. T h i s r e g u l a t i o n may involve e i t h e r a r t i f i - c i a l cooling o r a d d i t i o n a l h e a t i n g , according t o a s p e c i a l programme, of i n d i v i d u a l s e c t i o n s of t h e foundations s o i l s whose thawing l a g s considerably behind t h e thawing of t h e main ground mass under t h e s t r u c t u r e . Such addi- t i o n a l h e a t i n g aimed a t c o r r e c t i n g t h e s e t t l e m e n t of a water tower i n Trans- b a i k a l r e g i o n was s u c c e s s f u l l y c a r r i e d o u t i n 1942
-
1943 ( ~ e m e n t ' e v , 1944). Before undertaking any measures a f t e r t h e appearance of deformation i n t h e s t r u c t u r e , d e t a i l e d i n v e s t i g a t i o n s of t h e unfrozen a r e a should be con- ducted and t h e magnitude and r a t e of s e t t l e m e n t of t h e s t r u c t u r e determined.On t h e b a s i s of d a t a c o l l e c t e d , t h e reasons f o r deformation of t h e s t r u c t u r e a r e e s t a b l i s h e d and measures a r e planned t o e l i m i n a t e t h e s e deformations.
Maintenance of s t r u c t u r e s e r e c t e d w i t h p r e c o n s t r u c t i o n thawing of t h e foundation s o i l . To reduce expenditures, p r e c o n s t r u c t i o n thawing of t h e ground i s u s u a l l y conducted i n such a way t h a t i t covers only a p a r t of t h e a r e a s u b j e c t t o f u r t h e r thawing. Therefore c a r e should be taken t o secure an even and t h e slowest p o s s i b l e subsequent thawing.
The f r e e z i n g of thawed ground should not be permitted because i t may lead t o heaving of t h e ground and deformation of t h e s t r u c t u r e erected on i t . An i n t e r r u p t i o n o r d e l a y i n t h e c o n s t r u c t i o n work and breaks i n h e a t i n g of t h e s t r u c t u r e i n use may lead t o t h e f r e e z i n g of t h e t a l i k and t o t h e formation of masses of f r o z e n ground under t h e s t r u c t u r e . Under c o n d i t i o n s of normal oper- a t i o n , t h e p o s s i b l l i t y of such f r e e z i n g of t h e ground i s excluded.
I n c a s e s where t h e h e a t i n g of a s t r u c t u r e h a s t o be discontinued and i t
appears p o s s i b l e t h a t t h e prethawed ground under t h e s t r u c t u r e w i l l f r e e z e , i t
i s recommended t h a t boreholes be d r i l l e d f o r o b s e r v a t i o n s of t h e temperature and c o n d i t i o n of t h e foundation s o i l . I f f r e e z i n g of t h e thawed ground under t h e s t r u c t u r e i s discovered, measures must be taken t o maintain t h e ground i n t h e thawed s t a t e (covering and h e a t i n g ) .
In view of the novelty of the method of preconstruction thawing of the ground, observations of consolidation of the thawed ground after erection of the structure and during its use are of scientific and practical interest, These observations should be conducted by means of levelling the bench-marks installed in the walls and in the bearing elements of the structure, especial- ly during the first two or three years of use.
4. Maintenance of Structures Erected Without Taking Into Account changes in the Aggregate State of the Foundation Soils
The maintenance of structures is simplest in cases where the structures were erected under favourable lithological and hydrogeological conditions, where the structure and bearing capacity of the ground do not depend on temp- erature, and also in cases where the buildings were erected on unfrozen ground and the permafrost lies at great depth, and there are no reasons to expect that the erection of structures will result In freezing of ground that was formerly unfrozen.
In this case maintenance is reduced to upkeep of the built-up area and periodic inspection of the structure and adjacent area, especially of various protective installations, such as decking, gutters and others.
In cases where the permafrost occurs at depths ranging to 10 m and because of its properties belongs to the category of rather unfavourable ground (silty or with a hlgh moisture content), it is useful to carry out ob- servations of the permafrost table and of the changes in the thickness of the thawed layer beneath the structure. If signa appear indicating a disturbance in the stability of the structure in use, then it is necessary to check the position of the permafrost table beneath the structure and also the dimensions and form of the remaining thawed layer. If large changes are found which
threaten the future safety of the structure, then necessary measures should be developed and executed immediately, talcing into account all the established data and the present geocryological conditions.
In all other respects, the methods of maintaining structures do not differ from the usual methods applied in regions outside the area of peren- nially frozen ground.
5.
Special Features of Turning Over the Structures For OperationSpecial features in the construction and maintenance of structures erected in permafrost areas dictate special requirement8 in the turning over of these structures for operation, after all construction work has been fin-
1. In the process of turning over the structure for operation, the construction administration, in addition to the delivery of the usual docu- ments pertaining to the construction work, design and estimating, should de-
liver, and the agency taking over the structure should demand, the following documents :
(a) Description of geocryological conditions of the construction site together with an indication of the distribution and depth of occurrence of frozen ground, its temperature, depth of seasonal freezing and thawing, ground water regime and temperature. Also all the data pertaining to engineering- geological exploratory studies should be attached, including field records of exploratory borings, geological cores and sections, etc.
(b) Considerations concerning assumed changes in the regime and state of the permafrost after the erection of the structure.
(c) Documents indicating the method of construction of the structure and presenting an explanation of the reasons for using this method.
(d) Organizational outline of the construction work and a schedule of its daily accomplishment.
( e ) Daily reports on construction work indicating the time and conditions of execution, deviations from the planned work schedule, recorded temperature of outside air, etc.
(f) Documents stating what changes were introduced into the accepted design and indicating the reasons for these changes, new solutions taken, and results then obtained.
(g) Records of all observations, carried out during the periods of
engineering-geological survey and constmction work, pertaining to the follow- ing items: depth of seasonal thawing and freezing, ground temperature, ground- water level, grading records, etc.
(h) Special instructions concerning maintenance of the structure accord- ing to the geocryological conditons of the construction site and the selected method of construction.
2. The instructions on maintenance of the structure should include
directions aimed at establishing and preserving the thermal regime and state of the foundation soils predicated by the design and the selected method of
construction. Hence, the instructions should include the following material:
(a) The thermal regime of the frozen ground beneath the structure and the position of the frost table, as foreseen by the design.
(b) Description, programme and methods of regulating the operation of cooling installations, including the time of interruption in their operation during winter and summer.
thawing of the permafrost, then material should be presented on the process, magnitude and rate of this thawing, as foreseen in the design, as well as material on the dimensions of a developing basin and the magnitude and rate
of the structure1 s normal oettlement
.
(d) If the design calls for special installations to regulate the
progress of thawing of the frozen ground, then directions should be given con- cerning the use of these installations.
(e) In cases where special devices for adjustment of some elements of the structure undergoing differential settlement were installed in the course of construction work, instructions should be given for regulating and level- ling such elements as crane-supporting tracks, girders, supporting parts of machinery, etc.
3.
Together with the above-listed materials, the following data should also be delivered in the process of turning over the structure for operation.(a) List of boreholes used for temperature measurements, bench-marks, wall marks, frost gauges, resistance thermometer, frost-heave gauges and other devices for executing long-term observations; their location should be indi- cated in detail.
(b) Schedule of periodic inspection of the structure, cooling installa- tions, ventilation installations, the ventilated air space below the floor, and so on.
(c) Schedule of continuous observations: temperature measurements,
determination of the depth of thaw and amount of settlement of the structure, taking readings of frost gauges, frost-heave gauges, and other devices.
(d) Instructions on snow removal from the built-up area and on the regulation of snow accumulations around the structures, etc.
(e) Instructions on control over the diversion of surface and groundwater, over the operation of drains, gutters, ditches, and so on.
4. In the process of turning over for operation a structure erected by the method of preserving the frozen state of the ground, the commission in charge of taking over the structure should check and verify that the construc- tion work was executed according to the design and that the foundation soil is in a frozen state at the time of taking over the structure.
5.
In the process of turning over for occupancy a structure erected by the method of adjustment of the structure to thawing of the ground, the state of the ground beneath the structure should be. established at the time oftaking over the structure, and the depth of the permafrost table should be recorded.
6.
In the process of turning over for operation a structure erected by the method of prethawing the permafrost prior to construction, the commissiont a k i n g over t h e s t r u c t u r e should be c e r t a i n t h a t t h e f o u n d a t i o n s o i l i s
thawed t o t h e d e p t h s p e c i f i e d by t h e d e s i g n .
7.
I n t h e p r o c e s s of t u r n i n g o v e r a s t r u c t u r e f o r occupancy, i n a d d i t i o n t o t h e p r i n c i p a l s t r u c t u r e , s p e c i a l a t t e n t i o n should be devoted t o t a k i n g over a l l c o o l i n g and v e n t i l a t i o n i n s t a l l a t i o n s and a l l d e v i c e s used f o r l ~ n g - t e r m o b s e r v a t i o n s , such a s r e s i s t a n c e thermometers, w a l l marks, f r o s t - h e a v e gauges, f r o s t metres, and so on.8. The s t a t e of t h e f o u n d a t i o n s o i l s and t h e p o s i t i o n of t h e permafrost t a b l e beneath t h e s t r u c t u r e a t t h e time of t u r n i n g over t h e s t r u c t u r e f o r occupancy a r e e s t a b l i s h e d on t h e b a s i s of d a t a secured from o b s e r v a t i o n s c a r - r i e d o u t by t h e c o n s t r u c t i o n a d m i n i s t r a t i o n and from c o n t r o l measurements per- formed by t h e commission t a k i n g over t h e s t r u c t u r e . It i s n e c e s s a r y t o check whether t h e r e s u l t s of c o n t r o l measurements a g r e e w i t h p r e v i o u s o b s e r v a t i o n s .
9 . Taking over some s p e c i a l s t r u c t u r e s f o r occupancy should comply w i t h
t h e follolving d i r e c t i o n s :
( a ) I n t h e p r o c e s s of t a k i n g over i c e s t o r e h o u s e s and o t h e r above-ground s t r u c t u r e s b u i l t of i c e and f r o z e n ground, t h e c o r r e c t n e s s of t h e e x e c u t i o n of s t r u c t u r a l elements b u i l t of i c e o r f r o z e n ground should be checked, as w e l l a s t h e c o r r e c t n e s s of t h e i n s t a l l a t i o n of t h e i n s u l a t i n g l a y e r ; t h e tempera- t u r e i n s i d e t h e i c e s t o r e h o u s e should be recorded, a l s o t h e temperature i n s i d e t h e g a l l e r y i n t h e dam, and s o on.
I n s t r u c t i o n on t h e s p e c i a l f e a t u r e s of t h e p r o c e s s of t u r n i n g o v e r f o r occupancy s t r u c t u r e s b u i l t of i c e o r f r o z e n ground should a l s o be used in c a s e s where t h e s e s t r u c t u r e s were e r e c t e d i n a r e a s o u t s i d e t h e permafrost r e g i o n . I n t h e s e c a s e s , t a k i n g over of s t r u c t u r e s should proceed w i t h s p e c i a l c a r e . ( b ) I n t a k i n g over a n a r t e s i a n w e l l supplying water e i t h e r from a bed u n d e r l y i n g t h e f r o z e n ground o r from a thawed bed l y i n g between two f r o z e n ground l a y e r s , i t should be e s t a b l i s h e d t h a t no i c e b l o c k i n g o c c u r s i n t h e w e l l .
The a b o v e - l i s t e d requirements f o r t h e p r o c e s s of t u r n i n g o v e r completed s t r u c t u r e s a r e determined by a l l t h e s p e c i f i c f e a t u r e s of c o n s t r u c t i o n under permafrost c o n d i t i o n s and by t h e complexity of m a i n t a i n i n g t h e s e s t r u c t u r e s . Compliance w i t h t h e d i r e c t i v e s p r e s e n t e d i n t h i s c h a p t e r , as w e l l as meeting t h e requirements l i s t e d i n t h e s p e c i a l i n s t r u c t i o n s on maintenance o f t h e s t r u c t u r e , a t t a c h e d t o t h e t r a n s m i t t a l papers, w i l l f a c i l i t a t e observance of t h e e s t a b l i s h e d o p e r a t i n g c o n d i t i o n s of t h e s t r u c t u r e , w i l l i n c r e a s e t h e l a t - t e r ' s s t a b i l i t y and w i l l a s s u r e i t s normal u s e d u r i n g t h e e n t i r e p e r i o d of o p e r a t i o n .
6 . O r g a n i z a t i o n of Long-Term Observations of S t r u c t u r e s
Erected on P c r e n n l a l l y Frozen Ground
The n e c e s s i t y f o r continuous o b s e r v a t i o n s of t h e s t a t e and temperature of f r o z e n f o u n d a t i o n s o i l s has been mentioned r e p e a t e d l y i n t h i s c h a p t e r . T h i s requirement r e f l e c t s t h e s p e c i a l f e a t u r e s of m a i n t a i n i n g s t r u c t u r e s e r e c t e d i n permafrost a r e a s . These f e a t u r e s a r e n o t and cannot be involved i n t h e main- tenance of s t r u c t u r e s i n o t h e r a r e a s .
Depending on t h e method used i n t h e c o n s t r u c t i o n of t h e s t r u c t u r e , o b s e r v a t i o n s cover t h e f o l l o w i n g p o i n t s :
( a ) f o r s t r u c t u r e s e r e c t e d by p r e s e r v i n g t h e f r o z e n s t a t e of t h e ground
-
t h e l a t t e r ' s temperature and s t a t e beneath t h e s t r u c t u r e ;( b ) f o r s t r u c t u r e s e r e c t e d on thawing f o u n d a t i o n s o i l s
-
d e p t h , r a t e and u n i f o r m i t y of i t s thawing, r a t e and e x t e n t of t h e s t r u c t u r e ' s s e t t l e m e n t .( c ) f o r s t r u c t u r e s e r e c t e d without t a k i n g i n t o account changes o c c u r r i n g i n t h e s t a t e of t h e f o u n d a t i o n s o i l s
-
t h e s t a t e of t h e s t r u c t u r e .Continuous o b s e r v a t i o n s should be organized a s e a r l y as p o s s i b l e , p r e f e r - a b l y a t t h e very beginning of t h e c o n s t r u c t i o n work. The programme of o b s e r - v a t i o n s h a s t o be o u t l i n e d f o r each i n d i v i d u a l c a s e depending on t h e l o c a l n a t u r a l c o n d i t i o n s , s e l e c t e d method of c o n s t r u c t i o n , n a t u r e of t h e s t r u c t u r e and i t s s t a t e , and a l s o t a k i n g i n t o account a l l t h e above c o n s i d e r a t i o n s .
By way of example, we l i s t s e v e r a l i n s t i t u t i o n s having organized obser- v a t i o n s and c o n t r o l over t h e c o n d i t i o n of s t r u c t u r e s and b u i l d i n g s i n use i n such a way t h a t h i g h l y p o s i t i v e p r a c t i c a l r e s u l t s were o b t a i n e d . These i n s t i - t u t i o n s a r e as f o l l o w s : permafrost s t a t i o n s of t h e N o r i l t s k Combine and
D a l l s t r o i , a s w e l l a s a l l permafrost s t a t i o n s of t h e I n s t i t u t e of Geocryology of t h e Academy of S c i e n c e s of t h e USSR: i n Vorkuta, I g a r k a , C h i t a ( c l o s e d i n 1944), Yakutsk, Aldan and Anadyr ( c h a p t e r I1 of t h e volume; Dementlev, 1952; and o t h e r s ) .
Unf'ortunately, t h e s e o b s e r v a t i o n s a r e made and t h e "permafrost s e r v i c e t ' o p e r a t e s i n o n l y a few c o n s t r u c t i o n o r g a n i z a t i o n s and a t i s o l a t e d p r o j e c t s . We a r e v e r y g l a d t o mention t h e r e c e n t tendency t o o r g a n i z e such o p e r a t i o n s a t some l a r g e c o n s t r u c t i o n p r o j e c t s a s , for example, i n t h e Bratslc and I r k u t s k d i s t r i c t s .
T h i s g i v e s u s r e a s o n t o hope t h a t f i n a l l y a l l t h e b u i l d e r s and a g e n c i e s i n charge of t h e o p e r a t i o n of s t r u c t u r e s i n t h e n o r t h and n o r t h e a s t of t h e USSR w i l l o r g a n i z e a "permafrost s e r v i c e " i n o r d e r t o a c h i e v e s a f e t y and nor- mal o p e r a t i o n of b u i l d i n g s and s t r u c t u r e s .
References
1 . Dement1ev, A . I . Elimination of d i f f e r e n t i a l settlement of structures by a r t i f i c i a l heating. Veatnik Akademii Nauk SSSR, No. 9, 1944.
2 . Dementlev, A . I . Deformation of buildings due t o e f f e c t s of f r o s t and how t o eliminate i t . T r . In-ta merzlotov.
