Foam Light Soil Backfill Technology for Bridge Approach Bridge above Metro Section Tunnel

In this paper, a foam light soil backfill technique for bridge approach bridge above metro section tunnel is proposed based on the construction of two cross-bridge projects of Yayunda Renovation project above the east extension section tunnel of Guangzhou Metro Line 3. For the municipal bridge construction above the subway tunnel, the load of the bridge approach structure layer is bound to exceed the soil cover load, and corresponding measures must be taken during the construction above the subway tunnel to reduce the additional load on the upper part. The approach bridge is backfilled in the form of "foam light soil + geotextile + steel mesh" by taking advantage of the characteristics of light and high strength foam light soil. The results show that the use of light foam backfill can not only reduce the deformation of the subway tunnel, but also avoid the occurrence of bridge head jump and reduce the influence of post-construction settlement of the bridge approach. The overall construction period can be saved by 45 days and the construction cost can be saved by 780, 000 yuan. This technology introduces new materials, new technologies and new processes of foamed light soil, effectively improves and reduces the road load, meets the load requirements above the subway tunnel, and can provide reference for similar projects.