Особенности проектирования деревянных мостов автомобильных лесовозных дорог

Abstract

The supply of the national economy with forest resources is directly related to transport accessibility, the condition and development of the road network of forest-rich territories. Construction requirements for year-round and seasonal new forest roads are 2.1 and 9.3 ths km per year, respectively. The situation is complicated by the transfer of transport facilities to new heavier live loads. The previously used design shapes of transport structures are outdated and require new engineering solutions. This is especially relevant for wooden bridge structures, which are of primary importance to forest road builders. The research subject is the wooden bridge girder superstructures with spans of 12–18 m undergoing increased road loads compared to the previous ones. The research aims is the development of modern designs of wooden beam superstructures based on the composite girders made of logs, board-bar-dowel-nail blocks and factory-made laminated blocks. The research includes: superstructures with composite girders of logs combined by combdowel joints, a method for calculating superstructures with composite girders, design of a 15-meter experimental superstructure containing composite log girders in joint operation with roadway reinforced concrete slab; new designs of 15–21-meter superstructures with board-bar-dowel-nail blocks A11 and NK-80 for live loads, design procedure and technology of block manufacturing, examples of designed and built bridges with the 15-meter superstructures; designs of multi-ribbed superstructures made of prefabricated transportable one-piece laminated sections containing laminated beams and a multilayer laminated timber slab. The proposed designes with composite girders of logs (beams) and board-nail blocks can be manufactured on the sites and yards of logging organizations using commonly used equipment, local qualified staff and materials. The cost parameters of permanent bridges built in the Omsk region with the use of these designs are 1.5–2 times lower than those of reinforced concrete analogues. The use of these designs will be effective in the pilot method of forestry development. The use of laminated superstructures is related to the modern phase of forest infrastructure development.