# Adaptive Impulse Reconstruction of Seismic Signals Induced by TBM Drilling Noise via CEEMDAN-Assisted MDD Interferometry

## TL;DR

This paper introduces a new method to reconstruct seismic signals from TBM drilling noise, improving tunnel prospecting by enabling clearer interpretation of subsurface structures.

## Contribution

The novel approach combines CEEMDAN and MDD interferometry to adaptively reconstruct impulse responses from noisy TBM data.

## Key findings

- The proposed method produces more compact and coherent virtual-source gathers compared to existing techniques.
- Field tests confirm the workflow's feasibility and realistic moveout behavior in real tunneling conditions.

## Abstract

Tunnel ahead prospecting is important for reducing construction risks associated with faults, fractured zones, and cavities ahead of the tunnel face, but controlled active-source surveys are often impractical during continuous TBM operation. TBM drilling-noise records provide persistent passive excitation; however, strong nonstationarity and narrowband tonal contamination can hinder stable retrieval of interpretable impulse-like responses. We propose an adaptive impulse reconstruction algorithm that couples CEEMDAN-based mode screening with MDD interferometry. CEEMDAN screening suppresses quasi-stationary tonal components while preserving coherent propagation-related wavefields, producing effective signals suitable for interferometric processing. The MDD stage is stabilized using band-limited inversion, phase-only whitening, and a multi-reference strategy. Numerical experiments with a 3D elastic tunnel model indicate that the proposed workflow yields a more compact and laterally coherent virtual-source gather than correlation-based baselines (CC and PHAT-CC) and single-reference deconvolution interferometry, supporting reflection-oriented interpretation beyond simple wavelet compression. Field measurements from an operating TBM tunnel, together with a hammer-impact benchmark, are consistent with the feasibility of the workflow under real tunneling conditions and with physically plausible moveout behavior in the reconstructed gathers.