.png){kind=icon}
.png){kind=icon}
Return
Responses of existing tunnel to adjacent deep excavation in sand-gravel mixtures
.png){kind=icon}
PRE
AI
J
Y
Z
B
DOI：10.1007/s11440-026-03175-3.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
In the congested urban environments, construction of deep excavations close to existing tunnels poses significant risks and technical challenges, where an accurate prediction of the tunnel responses is crucial for optimizing design and reducing costs. However, the tunnel responses to adjacent excavations in the sand-gravel mixtures (S-GM), which have properties distinct from typical sands or clays, remained poorly understood. In this study, a series of 1g physical model tests were carried out first to identify the tunnel responses to an adjacent braced excavation in the S-GM strata with different rock (gravel) contents (RCs). Subsequently, the discrete element method (DEM) incorporating an algorithm for generating irregularly-shaped gravels was employed and calibrated against the experimental data. The validated DEM model was then utilized to examine the tunnel responses under two typical tunnel-excavation configurations: the parallel case (PC) and the underlying case (UC). Finally, micro-scale analyses were performed to uncover the underlying mechanisms of tunnel-excavation interaction. The results revealed a critical RC threshold of 60% for PC. Below this threshold, the excavation-induced increments in the tunnel’s internal forces and deformations increased with RC; beyond it, they decreased. This reversal was attributed to the formation of stable point-to-point contacts among gravel particles once RC $$>$$ 60%. For the UC condition, the excavation-induced tunnel responses varied across three distinct phases: a pronounced decrease at RC < 30%, marginal changes between RC = 30% and 75%, and a significant increase at RC $$>$$ 75%. This pattern stemmed from the mutual interlocking of gravel particles in the S-GM strata with moderate RCs (30–75%), which enabled the formation of a continuous arch structure above the tunnel. In contrast, the interparticle contacts at both low and high RCs were predominantly vertical, causing particle separation and consequent weakening of the strata. These findings provide valuable insights into the complex soil-tunnel-excavation interaction in the S-GM strata and offer direct guidance for risk assessment and mitigation in similar geotechnical projects.
Keywords:
Deep excavation
Model test
Micro-mechanism
Numerical modeling
Sand-gravel mixtures (S-GM) strata
Tunnel
Journal
IF:
5.7
Papers:
3.0K
Citations:
1.3W
Organization
Cited Papers