The existing over- and under-excavation detection methods cannot effectively adapt to variable
tunnel sections. To address this issue, an over- and
under-excavation detection method based on three-dimensional image reconstruction technology is proposed for variable
large cross-sectional tunnels. The tunnel axis serves
as the streamline, and the designed excavation cross-section
acts as the reference line. The variable-section
characteristics of the tunnel are represented by a section enlargement factor k, which is
used to construct a surface calculation equation suitable for such tunnels and
to form a calculation algorithm for the designed excavation contour. The
proposed method was applied to the Liuzhi-side tunnel
anchorage project of the Huajiang Canyon bridge. The control points are
established, and field photographs are collected. The actual excavation
contours of the variable-section tunnel anchorage are
reconstructed as point clouds and three-dimensional
(3D) surfaces using 3D image reconstruction technology. The grid-ray method is then employed to compare the actual excavation with
the designed variable section profiles, enabling the calculation of the over- and under-excavation. The accuracy of the
proposed method is validated by comparing its results with actual sprayed
concrete volumes and total station measurements. The results demonstrate that
the proposed method enables rapid and accurate detection of over- and under-excavation for each excavation
cycle in the variable-section tunnels. The average
relative deviation rate of the detection results is only 1.50%, which is
significantly lower than that of traditional methods (2.83%). The proposed
method expands the applicability of over- and under-excavation detection techniques, demonstrates excellent performance
in field applications, and provides a reliable basis for quality control during
the excavation of variable-section tunnels.
YANG Junsheng
,
LUO Yubo
,
FU Jinyang
,
CHEN Jianwei
,
WAN Zheng
,
ZHU Zhiheng
. Over- and Under-Excavation
Detection Method and Application of Variable-Section Tunnels Based on Three-Dimensional Image
Reconstruction Technology[J]. Tunnel Construction, 2025
, 45(4)
: 687
-694
.
DOI: 10.3973/j.issn.2096-4498.2025.04.003
