Abstract:

The integrity and continuity of rock mass will be reduced and the stability of surrounding rock will be affected due to fissure. The construction safety can not be guaranteed in case of delayed support or inadequate strength. A fast analysis method for the stability of tunnel surrounding rock based on 3D reconstruction and block theory is put forward relying on Jinggangshan Tunnel, so as to realize dynamic feedback and provide guidance for the design and optimization of construction scheme. The 3D reconstruction model based on the feature of fissures in the section with medium weathered sandstone and Grade Ⅳ surrounding rock is established in accordance with the geological sketch and statistical analysis. And then, the key block distribution, instability mode and safety factor in free face are analyzed by block theory. Finally, the dynamic feedback method for surrounding rock stability is proposed, and the different support schemes are comparatively analyzed. The study results show that: 1) The stability of surrounding rock is poor after excavation, and the corresponding supporting measures have to be taken; the anchor bolt support in original design scheme should be strictly carried out in accordance with dynamic feedback. 2) The dynamic acquisition, analysis and feedback of geological data during tunnel construction can be realized by fast analysis and dynamic feedback of surrounding rock stability based on 3D reconstruction; and in view of actual geological data, dynamic adjustment of support system and the economic benefits and safety of tunnel structure can be realized.

Key words: tunnel, characteristics of fissure, 3D reconstruction, stability of surrounding rock, fast analysis, dynamic feedback