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Influence of Catchment Caused by Local Overbreak on the Mechanical Characteristics of Tunnel Support Structure
(1.Hunan University of Science and Technology, Xiangtan 411201; 2. China State Construction Railway Investment & Engineering Group Co., Ltd., Beijing 102628)
Abstract The catchment caused by local overbreak of the tunnel increases the bearing burden of the supporting structure, and it is easy to cause groundwater leakage and cracking of support structure, thus influencing the construction safety. Based on it, in order to study the influence of catchment pressure on the deformation characteristics, stress characteristics, internal force changes and safety of tunnel support, the numerical model is established based on the tunnel excavation in the water-bearing section. The initial support of the tunnel is subjected to circumferential pressure to simulate the external water pressure. Five external water pressure conditions are set for comparative study, and the stress and displacement results of tunnel support at different positions in the same section are analyzed respectively. The results show that after the catchement of overbreak area occurs, the tunnel support structure will be displaced in the direction of the external water pressure due to the external water pressure distributed along the tunnel contour, and the main influence range is in the catchment area of the tunnel. Stress concentration occurs in the catchment area when catchment caused by overbreak occurs on the crown and shoulder of the tunnel.When the side wall is overbreakd, the maximum principal stress decreases and the minimum principal stress increases gradually. The external water pressure only affects the internal force of the catchment area. The increase of the external water pressure will increase the axial force and decrease the bending moment. In addition, when the catchment occurs at the crown, the crown bending moment gradually changes from negative bending moment to positive bending moment. The research results can provide technical reference for the deformation control of tunnel surrounding rock in water-bearing region and the reinforcement measures of supporting structure.
Abstract：
The catchment caused by local overbreak of the tunnel increases the bearing burden of the supporting structure, and it is easy to cause groundwater leakage and cracking of support structure, thus influencing the construction safety. Based on it, in order to study the influence of catchment pressure on the deformation characteristics, stress characteristics, internal force changes and safety of tunnel support, the numerical model is established based on the tunnel excavation in the water-bearing section. The initial support of the tunnel is subjected to circumferential pressure to simulate the external water pressure. Five external water pressure conditions are set for comparative study, and the stress and displacement results of tunnel support at different positions in the same section are analyzed respectively. The results show that after the catchement of overbreak area occurs, the tunnel support structure will be displaced in the direction of the external water pressure due to the external water pressure distributed along the tunnel contour, and the main influence range is in the catchment area of the tunnel. Stress concentration occurs in the catchment area when catchment caused by overbreak occurs on the crown and shoulder of the tunnel.When the side wall is overbreakd, the maximum principal stress decreases and the minimum principal stress increases gradually. The external water pressure only affects the internal force of the catchment area. The increase of the external water pressure will increase the axial force and decrease the bending moment. In addition, when the catchment occurs at the crown, the crown bending moment gradually changes from negative bending moment to positive bending moment. The research results can provide technical reference for the deformation control of tunnel surrounding rock in water-bearing region and the reinforcement measures of supporting structure.
AN Yonglin1 GUO Jindong1 ZHOU Jin1 HU Wei1 DONG Chenyang2 XIANG Hui2 DAI Ling2
.Influence of Catchment Caused by Local Overbreak on the Mechanical Characteristics of Tunnel Support Structure[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(5): 91-98
2022, Vol. 59 