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Study on Large Deformation Control Method and Structural Mechanical Characteristics of Shanyang Tunnel in Soft Rocks
(1. China Railway 23rd Bureau Group Corporation Limited, Chengdu 610072; 2. State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University, Chengdu 610065)
Abstract In order to effectively control the large deformation of soft rock in the thin-bedded broken shale section in the Shanyang Tunnel on Dali-Ruili Railway, a construction method has been proposed that is comprised of surrounding rock pre-reinforcement by curtain grouting, advance middle pipe umbrella and advance water exploring and pressure relief holes and the three-bench mechanical excavation. The side wall excavation curvature is increased to change the U-shaped excavation section to egg-shaped excavation section, the deformation allowance increases from 10 cm to 50 cm, and the initial support structure changes from the I25 single-layer steel rib with 1 m spacing to the double-layer HW175 steel rib with 0.6 m spacing. All these measures have solved the challenging problems such as steel rib distortion and cross section intrusion. According to force monitoring on the support structure on site, the forces on some of the steel ribs of double-layer initial support exceed their yield strength, mainly because the support structure sustains excessive force while the surrounding rock load is not adequately released. It is recommended to release a part of the surrounding rock pressure before construction of the second layer of initial support.
Abstract：
In order to effectively control the large deformation of soft rock in the thin-bedded broken shale section in the Shanyang Tunnel on Dali-Ruili Railway, a construction method has been proposed that is comprised of surrounding rock pre-reinforcement by curtain grouting, advance middle pipe umbrella and advance water exploring and pressure relief holes and the three-bench mechanical excavation. The side wall excavation curvature is increased to change the U-shaped excavation section to egg-shaped excavation section, the deformation allowance increases from 10 cm to 50 cm, and the initial support structure changes from the I25 single-layer steel rib with 1 m spacing to the double-layer HW175 steel rib with 0.6 m spacing. All these measures have solved the challenging problems such as steel rib distortion and cross section intrusion. According to force monitoring on the support structure on site, the forces on some of the steel ribs of double-layer initial support exceed their yield strength, mainly because the support structure sustains excessive force while the surrounding rock load is not adequately released. It is recommended to release a part of the surrounding rock pressure before construction of the second layer of initial support.
TIAN Baohua1 ZHAO Yongming1 WU Xingzhou1 ZHANG Biao1,
2 GAO Song1
.Study on Large Deformation Control Method and Structural Mechanical Characteristics of Shanyang Tunnel in Soft Rocks[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(3): 242-251
2023, Vol. 60 