2 Volumes Final Proceedings - Washington 1984.pdf - IARC Research

184etc. But where one uses prior thawing it is alsopossible to use foundations, including pile foundations,which stand separately from each other.Foundations involving girders, slabs, etc. mustbe built in conjunction with the design of theabove-ground structure. Calculation of the detailsof the total system embracing the building, itsfoundations and the sediments beneath, involvesboth determining the degree of settlement and itsprogress through time, and determining the forcesinvoked by that settlement in the foundation itselfand in the above-ground structure, whereby thefoundations are seen as a component part of thestructural system of the building. The method ofcomputer calculation of rhese aspects has beendeveloped for civil buildings by the Leningradinstitute LenZNIIAP and has been presented inarticles by L. E. Neymark, V. V. Dokuchayev, etc.When one examines the interaction betweenthawed sub-foundation sediments and the foundationof a building the following initial assumptions aremade. Taking into consideration the curvilinearoutline of the zone of thaw beneath the buildingthe settlement in the sediments beneath the stripfoundation will be variable along its length. Inkeeping with this the reactive forces transferredby the sediments to rhe underside of the foundationwill also vary. In the marginal parts of the foundationstrip, where the depths of thaw and theamount of sediment settlement are least. a concentrationof pressure will occur and the reactiveforces will reach maximum values P = P$. In thecentral part of the foundation strip where thawingb. spand settlement are at a maximum the reactive forcesare minimal and may even equal zero if the thawsettlement in the sediments (So) is greater thanthe flexure of the foundation strip and the sediments"pull away" from it (Figure 6). The curvedoutline of ?he surface is determined by the changein the amount of settlement (So) along the lengthof the foundation beams (where prior thawing hasbeen effected this value is close to zero). Theamount of reactive pressure can be determined bysolving the equation for the flexure of beams onan elastic foundation. In this connection thedesign model used for thawed sediments is theelastic-plastic model, the elastic strains which inare described by Winckler's theory ol local strains.The bed coefficient in this model is determined asthe ratio of load to the amount of compactionsettlement (C = P/sp) at any given point.ConclusionsIn concluding this review article I should liketo mention that the development of engineeringpermafrost studies has allowed us to erect a widevariety of structures on permafrost materials,including multi-storey buildings and large industrialinstallations, under any permafrost conditions.But of course this demands a thoroughpreliminary engineering-geology reconnaissance andcareful design decisions which observe all therequirements of building standards and regulationsand which are based on technological and economiccomparisons of possible variants; and naturallyconstruction must be carried out so that all therequirements of this type of industrial work aremet, One should also note that despite theachievements I have listed there are still a numberof questions which require further investigation.We hope that the solutions of these problems willbe achieved through the joint efforts of academicgeocryologists and construction engineers in allthe countries where permafrost occurs. The organizationof international conferencespermafrostsuch as this will undoubtedly facilitate such jointefforts.REFERENCESBuchko, N. A. et al., 1978, Isskustvennoye zamorazhivaniyegruntov [Artificial freezing of sediments].Gaydayenko, Ye. I., 1978, Ispol'zovaniye l'dov vkachestve osnovaniy sooruzheniy [Use of as icea structural foundation].LenZNIIEP, 1977, Fundamenty na sil'nol'distykh izasolennykh vechnomerzlykh gruntakh [Foundationsin ice-rich and saline permafrost materials],Mel'nikov, P. I., and Vyalov, S. S.,PQ s=s,+s,e, 1981,Ottaivayushchiye grunty kak osnovaniya sooruzheniy[Thawing sediments as foundations forFIGURE ti Diagram of foundation design.structures].a) elastic-plastic model of sub-foundation sediments Poluektov, V. Ye., 1983, Ustroystvo fundamenrov vshowing relationship of settlement compaction vechnomerzlykh gruntakh [Construction of foun-Sp to load;dations in permafrost materials].b) diagram of interaction between the foundation Roman, L. T., 1981, Fiziko-mekhanicheskiye svoysrvastrip and the sub-foundation sediments;merzlykh torfyanykh gruntov [Physico-mechanicalc) diagram of reactive pressures in the sediments. properties of frozen peat].