Justification of the forces required for leveling ends of floating packaged rafting units

When implementing the concept that ensures the economic accessibility of remote forest resources, it is envisaged to raft small-sized packages of round timber into bilevel units at the points of exit from shallow-water sections of rivers to deep-water ones. The specified raft is assumed in special devices, which provide the leveling ends of rafting units to increase the economic indicators of further transportation and the reliability of maintaining integrity. To substantiate the parameters of the device, information is needed on the required forces for leveling ends of floating packages and bilevel units of them. It was found that to obtain it requires additional research. The expediency of a common methodology for bilevel units and their constituent packages is obvious, from which research should be started. To obtain the dependence for calculating the force required for leveling ends of the floating packages, a theoretical method based on the elastic theory was used. In this case, the floating package was considered as a flexible shell filled with two types of granular media with different bulk density. The boundary of the media runs along the surface of the water. The strapping line, that is, the flexible casing, is a combination of fragments of two elastics with different characteristics. Using parametric equations describing the shape of elastic and dependences for determining pressures in bulk media, we obtained the required analytical dependence and its simplified version for practical calculations. The calculation results according to the proposed formula exceed the results calculated according to the formula obtained earlier using another algorithm of actions without considering the pressure of the straps by 70% with a package shape factor of 1.5, that is, with a strong pressure of the straps and by about 10% – with a coefficient of 2.5, that is, their weak pressure. This allows us to consider the results of the study reliable, the use of the methodology used for the corresponding study of bilevel units is expedient. It was found that at a fixed density of timber, the most significant effect on the force of leveling ends is changes in the ratio of the height of the package to the average diameter of timber, its shape factor and volume. The influence of the first two factors in the analytical formula is considered by a factor, the value of which in practical calculations can be determined from the proposed graphs or approximating dependences.

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