Abstract：
By taking a tunnel in the Daban geological zone in Xinjiang for example, the long-term stability of mud?
stone tunnel invert has been analyzed. After analysis of the tunnel rock mass structure, rock strength and long-term deformation monitoring data, the mechanical parameters and creep parameters of the monitored tunnel rock mass have been obtained by using the H-B strength criterion and BP neural network algorithm. By using the CPOWER model built in the FLAC 3D software, the numerical simulation model for typical section has been created, so as to analyze how various lining support strengths and invert radius of curvature will affect the stability of tunnel invert under the rheological effect of mudstone in the operation period. The results indicate: with mudstone rheology taken into account, the main deformation of tunnel is the heave at the center of invert. First increase of support strength or decrease of invert radius of curvature will significantly improve the stress state of tunnel structure, inhibit surrounding rock deformation and reinforce the stability of surrounding rock. However, as the support strength continues increasing
or the invert radius of curvature continues decreasing, this inhibiting effect gradually becomes weaker. When the support is changed from I16 I-beam to two-layer arch frame, the center of invert still has 11.14 mm heave. When the invert radius of curvature is reduced from 16 m to 14 m, the heave at the center of invert is reduced from 33.7 mm to 3.37 mm, and the eventual displacement meets the requirements for later stage of tunnel operation. Compared with increasing the support strength, reducing the invert radius of curvature will fundamentally inhibit the heave at the center of invert, and also allow more even stress on surrounding rock and support structure. When the invert radius of curvature is properly reduced in the construction stage, the tunnel is in a relatively balanced state, and the rheological effect does not significantly affect the stress state of the tunnel.
of curvature
210
SI Ninghu1 ZHAO Chunpeng2 CHANG Zhou1 YAN Changgen1 LAI Hongpeng1 LU Zhifang3 XIE Wanye1
.Analysis of Long-term Stability of Mudstone Tunnel Invert—Case Study of
a Tunnel in Daban Geological Zone in Xinjiang[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(6): 199-210
2023, Vol. 60 