چكيده به لاتين
Deterioration of stone ballast is one of the most important issues in the field of maintenance and repair of ballast rail lines, and providing solutions to improve performance and reduce the speed of its deterioration will be an important step in reducing the speed of line deterioration and maintenance costs of rail lines. Ballast correction and stabilization methods are used to reduce the problems caused by ballast behavior and also to prevent its early deterioration. In general, the ballast modification and stabilization methods can be classified into two categories, mechanical, such as: placement of geogrids, geosynthetics, crumb rubber, etc., and non-mechanical, such as: injection of bitumen and bituminous mixtures, injection of bitumen-cement mortar, etc. So far, various studies have been conducted regarding ballast stabilization by mechanical methods. An example of them is the use of geogrid networks due to their excellent characteristics such as appropriate tensile strength in reinforcing and separating embankment layers and road and railway pavement layers. Also, in recent years, in order to improve the behavior of ballast lines and increase its lifespan, extensive research has been done in the field of using crumb rubber in different ways in the ballast layer. Using worn tires and recycling them has a significant effect in reducing environmental pollution. Until now, in the technical literature, rubber bands have not been used as a mechanical stabilization method for ballast stabilization; But there are examples of its application in geotechnical and soil issues. In this study, by introducing a new type of geogrids made with the help of worn rubber belts called geoscraps with dimensions of 5×5, 10×10 and 25×25 meshs, their effect on high shear behavior was investigated in a large-scale shear test. given. In this regard, by selecting the highest granulation according to group 4 of Iran publication 301 and placing geoscraps at different levels of 6, 12, 18 and 24 cm from the bottom of the bottom box, several tests were performed under vertical overheads of 50, 100 and 150 kilopascals and the results in Shear stress-shear curve, maximum shear strength, angle of internal friction and angle of expansion are presented. The summary of the results shows that the 5x5 spring at the level of 12 cm from the bottom of the box has provided the most favorable conditions for the ballast in terms of increasing the shear strength, increasing the internal friction angle and decreasing the expansion angle. So that at a load of 50 kPa compared to the unarmed state, the shear resistance increases by 30%, the internal friction angle increases by 9%, the dilatancy angle decreases by 29%, at a load of 100 kPa compared to the unarmed state, the shear resistance increases by 13%, the friction angle by 5%. increase, the expansion angle decreases by 27%, in the overhead of 150 kPa compared to the unarmored state, the shear resistance increases by 16%, the friction angle increases by 8%, and the expansion angle decreases by 32%.
