Investigating the static and dynamic abnormalities of forest road culverts in different numbers of traffic

The creation and construction of a forest road disturbs the natural balance of water flow in the forest area. This balance can be maintained to a large extent by installing culverts and building side channel in different traffic routes. culverts or drainage structures, as well as the road surface, often show behavior and signs before any kind of abnormality and destruction as a result of the effects of different vehicles on the road, which are related to the behavior of these signs. The ability to identify the severity of destruction and act on protection in time.

In this research, the static and dynamic anomalies of the culverts and forest road surface in different traffic levels in series one of Reyhanabad and series one of Pajim of Al-Ghadir Khalil Shahr forestry project were investigated. First, the specifications of all culverts (pipes, Made of concrete) including the thickness, diameter and length of the culvert, depth, slope and angle of its installation, the slope of the road and the flow rate of the culvert in the routes with different traffic numbers, measured with meters and inclinometers. The flow rate was calculated by measuring the cross section of the flow and the flow velocity according to the hydraulic radius, Manning's coefficient and flow slope. In the section of static anomalies, the level of health of the culvert in 4 floors was checked, as well as the unpaved road condition index (UPCI-unpaved road condition index) was measured. The dynamic abnormality includes the amount of vibration of the culvert when passing vehicles, which was calculated with the vibration meter application.

The results showed that with the increase in the installation depth of the culvert and the number of traffic, the numerical value of UPCI decreases. The lowest UPCI index values were recorded in longitudinal slopes of less than 5%. The health of the culvert increased with the increase of its installation angle. On the other hand, the lowest values of culvert health were recorded in longitudinal slopes of less than 5%. In general, the lowest level of vibration was recorded in the case of unarmored culverts that were installed at a depth of 50-100 cm, with a longitudinal slope of 5-8% and an angle of 100-120 degrees on low-traffic roads. In the routes with more than 4 vehicles per day, the vibration level of the culvert was estimated to be 2.24 Richter and in the routes with less traffic, the vibration level of the culvert was estimated to be 1.99 Richter. The reinforcement and the depth of the culvert also had a positive effect on the level of vibration of the culvert.

During road construction, observe points such as loading capacity, timely stabilization of the road, taking into account the shear position, timely compaction as well as implementing consolidation operations, taking into account hydrological properties (number of culvert crossings, water flow rate, transverse slope and moisture regime), creating ponds, applying operations. A course in road maintenance (current and periodic) on a continuous basis in forest roads, compliance with depth, reinforcement, longitudinal slope of the road, angle of installation relative to the axis of the road and taking into account the number of traffic in the design of the culvert It is necessary and can be effective in its health, vibration and efficiency.Key words: Unpaved road condition index, Gravel road, Forest road, Tubing.