Strains Determination in the Flexible Tie of a Packaged Log Rafting Overland Bundle

Complete text of the article:

UDС

DOI:

Abstract

Developed construction and technology of raft assembly of packaged log rafting bundles make possible to form the rafts in the winter season by small logging enterprises, allowing to decrease the transportation costs avoiding sufficient investments.Taking into consideration significant increase of the requirements for ecological safety of the timber floating and elimination of wood substance losses during its waterborne transport, the correct evaluation of the forces in the flexible ties of a packaged log bundle is becoming more important. This problem is solved on the base of combined method based on theories of elastics and free-flowing medium. The highest strains in the flexible ties arise while it is on overland. This case was taken as a calculation. An assembly of bundle logs is considered as a free-flowing medium affected by gravity forces. For finding of vertical pressures in this medium it is requires to know a characteristic height, which determines the position of piezometric surface. Based on elastics theory, the dependencies between characteristic height, vertical dimension of a bundle and its shape coefficient, including a modular angle, which cannot be measured in practical conditions, were found out. In order to eliminate a modular angle, a term of relative characteristic height and the graphic charts for its evaluation were introduced. A vertical compression of a free-flowing medium causes horizontal pull out forces balanced with reactions in the strappings of the bundles. Equations for evaluation of equivalent forces in upper and lower packages were developed. Reactions in the upper and lower strappings of both packages were derived from the momental equations. The graphic charts for determination of tensioning coefficients (introduced term) were worked out. It was proved, that the bundle strappings ought to be computed upon the external forces applied during packaging.The results presented in the article allow to determinate the raft gearing tensions for a packaged log overland bundle. Besides that, the data obtained could be applied for assessment of relationship between parameters of a package and longitude stability of a log bundle during water transportation. 

Authors

• S.V. Posypanov, Candidate of Engineering, Associate Professor
  
  Northern (Arctic) Federal University named after M.V. Lomonosov,
  Naberezhnaya Severnoy Dviny, 17, Arkhangelsk, 163002, Russia;
  e-mail: s.posypanov@narfu.ru

Affiliation

Keywords

References

1. Abukhanov A.Z. Mekhanika gruntov [Soil Mechanics]. Rostov-na-Donu, 2006. 352 p.
2. Vorob'ev A.G. O raschete po elastikovoy teorii puchkovykh plotov dlya sluchaya nakhozhdeniya ikh na sushe [Application of the Elastics Theory for Design of Log Bundle Rafts Placed Overland]. Lesoinzhenernoe delo, 1958, Iss. 3. p. 40.
3. Instruktsiya po ekspluatatsii takelazha na lesosplave [Rules for Usage of Rigging at TIMBER floating]. Moscow, 1980. 134 p.
4. Kamusin A.A., Dmitriev Yu.Ya., Minaev A.N., Ovchinnikov M.M., Patyakin V.I., Pimenov A.N., Polishchuk V.P. Vodnyy transport lesa [Water Timber Transport]. Moscow, 2000. 432 p.
5. Posypanov S.V. Kombinirovannyy metod rascheta paketa kruglykh lesomaterialov, ulozhennogo na gorizontal'nom osnovanii [Combined Calculating Method of Round Tim-ber Pile Stacked on Horizontal Foundation]. Lesnoy zhurnal, 2011, no. 1, pp. 47–52.
6. Reutov Yu.M. Raschety puchkov (paketov) kruglykh lesomaterialov [Design of the Bundles/Packages of Roundwood]. Moscow, 1975. 152 p.
7. Fikhtengol'ts G.M. Kurs differentsial'nogo i integral'nogo ischisleniya [Course of Differential and Integral Calculation]. St-Petersburg, 2009, vol. 2. 799 p.
8. Kharitonov V.Ya., Posypanov S.V. Opyt vnedreniya edinogo transportnogo paketa vmesto molevogo lesosplava [Experience of Introducing Transport Package instead of Drift Floating]. Lesnoy zhurnal, 2007, no. 1, pp. 45–52.
9. Craig R.F. Soil Mechanics, 6th ed. London, New York: E & FN Spon, 1997. 485 р. 
10. Whittaker E.T., Watson G.N. A Course in Modern Analysis, 4th ed. Cambridge, England: Cambridge University Press, 2009. 620 p.