The effect of backfill grout hardening on Impact-Echo signal numerical analysis

초록

The aim of this study is to analyse the Impact-Echo (IE) signal characteristic of backfill grout in shield TBM during hardening. IE test on simplified 2-layer model (e.g., segment and grout layer) is simulated by using Finite Element Method (FEM) software. Three different hardening state of backfill grout were selected and simulated. Time domain signal obtained from IE test were analysed with Fast-Fourier Transformation (FFT) and Short Time Fourier Transformation (STFT). As the backfill grout hardens, damping ratio increases and resonance duration decreases. This result can be the basis for the derivation of thickness of two-layer system composed with segment and backfill grout during hardening process.