Study On Advanced Support Of Tunnel Based On Polymer Permeation Grouting

In order to meet the needs of China’s continuous social progress and sustainable and healthy economic development,the state continues to build a large number of Highway,Railways,Water engineering.Whether it is the tunnel in the highway,railway engineering or the tunnel in the water conservancy project,often because of the complexity of the tunnel and tunnel excavation,it has become the key and difficult point in the overall project.Especially when the tunnel is built in the weak surrounding rock represented by sand layer and gravel layer,due to the extremely poor cohesive force between the particles in the surrounding rock,the instability of the surrounding rock is easy to occur when disturbed,and the instability is occasional.Once the instability of the surrounding rock occurs,the consequences are extremely serious.Therefore,it is an effective method to strengthen the surrounding rock in advance and improve its stability to ensure the smooth excavation of tunnel.In this paper,the advanced supporting tunnel with permeable polymer is studied from two aspects of finite element numerical simulation and model test.In the aspect of finite element numerical simulation,the ABAQUS finite element analysis software is mainly used to establish a three-dimensional calculation model.Through reasonable setting conditions,the influence of the penetration polymer grout advanced reinforcement of tunnel surrounding rock on the settlement of the surface and different locations under the surface,as well as the mechanical parameters of the lining vault and the waist of the arch is studied.In the model test,the diffusion mechanism of permeable polymer grout in a variety of media and the main factors affecting the diffusion range,the consolidation physical properties formed by the diffusion of the grout in the media and the overlapping of the diffusion range of the grout are mainly explored.At the same time,an irrigation tunnel in Henan Province is taken as the research object,and the engineering case study is carried out from the perspectives of finite element numerical simulation and engineering practice.According to the above research contents,the results of this paper are as follows:(1)The three-dimensional calculation model of tunnel excavation is established with the finite element analysis software ABAQUS,and two working conditions of grouting reinforcement group and grouting reinforcement group are set up.In order to more close to the engineering practice,by using ultra short steps excavation tunnel,through the contrast analysis of two kinds of surface subsidence in the process of tunnel excavation and lining under the condition of stress and strain data,such as slurry forepole tunnel surrounding rock,it is concluded that the polymer formed in tunnel excavation contour area peripheral grouting reinforcement ring,grouting reinforcement ring has good mechanical properties,to a certain extent,the tunnel excavation area is in a state of "no force",so that the gravel tunnel excavation.(2)The diffusion mechanism of permeable polymer grout in sand layer and sand and stone mixture layer with different mix ratio and the influence of grouting pressure,grouting amount and porosity on the diffusion range of the grout were investigated by model test.The grouting consolidation body in sand layer and sand and stone mixture layer has good mechanical properties,and the bearing capacity of sand layer by adding permeable polymer grout is significantly improved.(3)By means of model test,the diffusion mechanism of permeable polymer grout with flowery tube grouting in sand layer and sand and stone mixture layer with different mix ratio and the influence of grouting quantity,grouting pressure,porosity and other factors on the diffusion of grout were investigated.When using flower-tube grouting,the position of flower-tube grouting can be reasonably arranged,so that the slurry diffuses to form columnar consolidation body overlapping with each other,forming "arch" or "annular" consolidation whole according to the need.(4)Taking a water conveying tunnel in an irrigated area of Henan as the engineering object,the effectiveness of permeable polymer advanced supporting tunnel in sand and gravel layer was verified through finite element numerical simulation and engineering practice.