Two standards need to be determined for railway ballast.
1. Selection of railway ballast material and determination of filling particle size
Railway ballast is the excavated surface layer of mountain debris, which is classified by color into yellow, red, and black. According to observation experiments, black ballast produced in Deqing, Zhejiang and red ballast produced in Changxing, Zhejiang have low strength, excessive weathering, and are easily crushed by rolling, making them unsuitable as roadbed fillers. The yellow ballast produced in Huzhou, Zhejiang Province has uniform stone quality, is not weathered, has no cracks, a smooth surface, and a strength of over 15Mpa.
Based on the condition of the raw materials of the ballast and combined with the actual engineering situation, the engineering and technical personnel have repeatedly studied and agreed that the roadbed should use mixed ballast with large particle size less than 10cm, containing 30% mud (stone powder); The subgrade shall be made of granular material with a particle size of less than 20cm and a mud (stone powder) content of 20%; The roadbed mainly uses ballast with a particle size between 25-30cm, and ballast with a size of 1.5-15cm for joint filling and leveling, with a mud (stone powder) content of 20%; The lower roadbed mainly uses ballast with particle size between 30-40cm, and 1.5-20cm ballast for joint filling and leveling, with a mud (stone powder) content of 10%