# A Study on Three-Dimensional Flexible Mesh Influence on the Stability of Reserved Tunnels in Cemented Backfill

## TL;DR

This study shows how adding a 3D flexible mesh improves the stability of tunnels filled with cemented backfill.

## Contribution

The novel contribution is the experimental and numerical validation of a 3D flexible mesh's effectiveness in enhancing backfill stability.

## Key findings

- Three-dimensional flexible mesh increased backfill tensile strength by 1.57–2.00 times and shear strength by 2.00–2.56 times.
- The mesh reduced roadway roof displacement by 21.43% and strain energy by 40% under static pressure.
- The mesh also hindered detachment of backfill fragments after damage from external forces.

## Abstract

Ordinary backfill has characteristics such as low compressive strength, low tensile strength, and easy bending, which cannot meet the stability requirements of reserved tunnels, but three-dimensional flexible mesh can be added to improve it. In this paper, mechanical characteristics and displacement were taken as the evaluation index, an optimal three-dimensional flexible mesh was studied by a laboratory experiment of small samples, then backfill with a reserved roadway was used to carry out a large-sample similarity simulation experiment, and finally, a numerical simulation was carried out. The research shows that the three-dimensional flexible mesh had a strengthening effect on the backfill, especially on the tensile strength and shear strength of the backfill. The strengths increased by 1.57~2.00 times and 2.00~2.56 times, respectively. After backfill is damaged by external forces, three-dimensional flexible mesh can also hinder the detachment of backfill fragments. The effect of the three-dimensional flexible mesh on the backfill under static pressure was calculated by using numerical simulation, and it was found that the three-dimensional flexible mesh played an effective support role for the roadway inside the backfill, effectively reducing the displacement of the roadway roof by 21.43% and the strain energy by 40%.