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Grouting reinforcement was used to improve rock strength and avoid seepage in rock engineering. A self-developed visualised test platform was developed and the influences of different fracture openness on grouting diffusion modes were revealed; the Bingham rheological model was imported to simulate the grouting diffusion process in a single plate fracture, the spatiotemporal distribution of the velocity field under different obstructions was determined using the finite element method. The results indicate that (i) the grout diffuses faster with the increase of fracture openness, while a stagnation effect of the grouting diffusion velocity behind the obstruction occurs. (ii) Due to obstructions, the grouting diffusion process can be divided into four stages: circular diffusion, flat diffusion, vortex diffusion, and butterfly diffusion. (iii) The grouting diffusion area is divided into a fully reinforced zone and a semi-reinforced zone, and the area of the latter increases with the fracture openness, while being little affected by the size of any obstruction. (iv) Furthermore, some new grouting diffusion laws were revealed considering the asymmetrical arrangement of obstructions. The results presented in this work will be helpful for describing and predicting the grouting process in fracture networks. Key words: rock mass fracture, grouting diffusion, visualised test, refined numerical simulation, obstructions. L'armature d'injection a ete utilisee pour ameliorer la resistance de la roche et eviter les infiltrations dans l'ingenierie rocheuse. Une plateforme d'essai visualisee a ete mise au point et les influences des differentes ouvertures de fracture sur les modes de diffusion des coulis ont ete revelees; le modele rheologique de Bingham a ete importe pour simuler le processus de diffusion de l'injection dans une fracture a plaque unique, la distribution spatio-temporelle du champ de vitesse sous differentes obstructions a ete determinee en utilisant la methode des elements finis. Les resultats indiquent que (i) le coulis diffuse plus rapidement avec l'augmentation de l'ouverture de la fracture, tandis qu'un effet de stagnation de la vitesse de diffusion du coulis derriere l'obstruction se produit. (ii) En raison des obstructions, le processus de diffusion du coulis peut etre divise en quatre etapes : diffusion circulaire, diffusion plate, diffusion tourbillonnaire et diffusion papillon. (iii) La zone de diffusion de l'injection est divisee en une zone entierement renforcee et une zone semi-renforcee, et la superficie de cette derniere augmente avec l'ouverture de la fracture, tout en etant peu affectee par la taille de l'obstruction. (iv) En outre, de nouvelles lois de diffusion de l'injection ont ete revelees en tenant compte de la disposition asymetrique des obstructions. Les resultats presentes dans ce travail seront utiles pour decrire et predire le processus d'injection dans les reseaux de fractures. [Traduit par la Redaction] Mots-cles: fracture du massif rocheux, diffusion de l'injection, essai visualise, simulation numerique raffine, obstructions., 1. Introduction Grouting improves the strength of fractured rock and prevents groundwater from flowing into tunnels. This method has the advantages of rapidity of effect, a short construction period, and [...]

The assembled corrugated steel initial support structure is a new prefabricated structure in highway tunnel engineering, achieving a balance between economy and safety. This study proposes a simplified calculation method and elucidates the mechanical mechanisms of assembled corrugated steel initial support structures. Firstly, the stiffness characteristics of corrugated steel plates were studied based on full-scale tests. A general equivalent stiffness coefficient table was established. Numerical simulations of corrugated steel flange joints were conducted to explore their bending mechanical properties. A two-stage rotational stiffness model for corrugated steel flange joints was proposed. Finally, a plane strain-spring simplified calculation method for the assembled corrugated steel initial support structure was developed, and the monitoring data from the Qipanshan Tunnel validated the correctness and reliability of the proposed method. The results demonstrate that (1) the plane strain-spring simplified model consists of the planar strain equivalent calculation method for corrugated steel plates and the two-line stiffness equivalent spring of the corrugated steel flange joint. The simplified model was validated as effective by monitoring data. (2) Corrugated steel plates exhibit two stages under loading, namely gap elimination and elastic stages. The elastic stage stiffness of corrugated steel plates decreases with increasing ratio of depth to pitch (RDP), positively correlating with plate thickness when the RDP exceeds 0.333 and otherwise negatively correlated. (3) Corrugated steel lining flange joints exhibit distinct elastic and plastic stages in their linear moment–rotation curves under loading. [ABSTRACT FROM AUTHOR]