The performance of construction waste backfilling subway depot—A case study in Zhengzhou

The construction of a large site section of the subway will lead to the demolition of large buildings and produce much solid waste. It wastes resources, increases construction costs, and seriously impacts the relevant national carbon emission targets. In order to solve the above problems, the compaction test, CBR test, compactness test, K30 test, and static load test were carried out in this study. This paper compares the performance difference between construction waste recycled material and traditional material and explores the application method of construction waste recycled material in subgrade backfilling. The ratio of brick concrete, moisture content, and particle level significantly influences the backfill performance. Test the proportion of brick concrete in construction waste 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, 10:0. The moisture content varies from 5% to 14%. The material was divided into three groups according to the particle size: passing 50 mm, passing 31.5 mm and passing 4.75 mm, and the particle grading design was carried out. The results showed that: when the particle size ratio of passing 50 mm, passing 31.5 mm and passing 4.75 mm is 100:90:45, the brick to total brick concrete is 50%. The moisture content is 12%, the characteristic value of subgrade bearing capacity can reach 400kPa, the strength is better than that of traditional backfill materials, and it meets the design requirements of each backfill area of the metro rolling stock section. In addition, ABAQUS software was used to simulate the load test and proposed a method to predict the foundation’s bearing capacity based on the recycled material’s performance parameters. This research is applied to the depot of Zhengzhou Metro Line 12 and provides a reference for the resource utilization of construction waste in the large site of the metro.