Mechanism And Stability Analysis Of Grouting Reinforcement For Soil Pillar In Small Spacing Tunnel

With the rapid development of urban traffic engineering in China,it is limited to the problem of construction space in urban traffic construction.In many practical projects,in order to make full use of urban space,the construction of urban highway tunnel is widely used.In the course of construction of urban underground tunnel,the tunnel should be designed as a small spacing tunnel type because of the influence of the building,pipeline and road on the ground.It has added a lot of difficulty to the construction of the tunnel.Through reasonable construction methods and effective reinforcement measures,the small distance tunnel can be guaranteed to a great extent.The stability of the surrounding rock,especially the septum column.In this paper,relying on the project of the small spacing tunnel of Yuhan Road,studying the mechanism of surrounding rock improvement after grouting reinforcement of the soil medium rock septum column in the small spacing tunnel through the laboratory test,numerical simulation and field test,and reveals that the grouting reinforcement of the soil medium rock column has been carried out to the whole tunnel surrounding rock.In order to evaluate the stability of surrounding rock,the stability of surrounding rock is evaluated mainly from several important indexes,such as stress,displacement and plastic zone,and the positive effect of grouting reinforcement on the stability of the surrounding rock of small distance tunnel is evaluated.By combining the force analysis model of small spacing tunnel,the improvement mechanism of grouting reinforcement to the stability of the small spacing structure type surrounding rock was studied.Through the analysis of the angle formula of the simplified fracture surface,the grouting reinforcement can make the angle of the fracture surface larger,and then result in the smaller or even disappearance of the affected zone,and thus the improvement of the broken zone.The stability of the rock column and the surrounding rock in the tunnel was improving.The numerical simulation method was used to analyze the changes of the stress and deformation of surrounding rock before and after the grouting reinforcement of the septum column,and the effect of the grouting reinforcement on the whole structure of the tunnel is revealed.Through the numerical simulation of several working conditions,the influence factors of the stress and deformation of small spacing tunnel are studied.The main factors affecting the stability of the rock column and surrounding rock in the small distance tunnel were the net distance of the tunnel,the depth of the buried and the surrounding rock conditions,and the analysis of the stress and the displacement of the key points of the tunnel surrounding rock under different conditions.Through the physical test,the characteristics of the stress and deformation of the middle rock column and the surrounding rock during the excavation of the small tunnel were studied.The rock displacement and the stress variation around the tunnel before and after the grouting are analyzed.The improvement effect of the grouting reinforcement on the overall stability of the tunnel surrounding rock is discussed,and this will provide a certain reference to this kind of similar work.Combined with the small distance tunnel of Yuhan Road,through the field test,the change of the settlement,horizontal convergence and surface settlement of the tunnel vault in the construction process was analyzed,and the variation law of the displacement of the isolated rock column and the surrounding rock displacement with time was summarized,and the key points of monitoring and controlling the small spacing tunnel were analyzed,and the small spacing tunnel was revealed.The effect of grouting reinforcement of diaphragm column in actual engineering is also a reference for the design and construction of shallow buried tunnels with small spacing in similar projects.