Study On Stress And Deformation Of Shallow Embedded Tunnel In Weak And Water-rich Strata By Similar Model Test

The main problem of urban underground construction by Shallow Mining Method at the present time is that formation disturbance in excavation led to displacement and stress redistribution of the surrounding formation、surface subsidence and destruction and influence of around road、construction and underground pipelines. Therefore,how to prevent formation collapse during the construction process of the urban underground engineering,how to protect the buildings and underground pile lines along the construction by the means of ensure the safety of the supporting structure and predict and control the surface subsidence efficiently has become an important subject which should be solved during urban subway construction.In this paper, Guanhui rail construction GZH-5tenders for the engineering background to DK32+300～DK32+927.303segment as the research object, through the model test construction process Shallow Tunnels Tunnels and the supporting structure of the force deformation law, the impact of excavation on surface subsidence and deformation and internal force ahead of grouting on the formation and surface deformation.After the similarity ratio is deterred to25,the paper does a lot of ratio test and developed some similar materials which is fit for this model test, that is:silt whose particle size is less than0.075mm and saturated solution of cellulose are selected to simulate the soil and water,a mixture with a mixing ratio of cement:water glass:calcium chloride=1:1:0.12is used to simulate jetting concrete, the Plexiglas is used to simulate the steel arch.In accordance with requirements of the geometric similarity ratio n=25,2times the hole diameter of the boundary size, wedeveloped a detachable box that can dynamically control the water pressure, and a small box whose similarity ratio is the same to the big box is produced as an as early demonstration test. A grouting equipment is developed, and on this basis, a device is developed for spraying concrete.With the materials and equipments described above,the paper achieves the entire experiment of filling, full-face grouting, excavation and removal of the wall, in accordance with the measurement program,the surface displacement, crown settlement displacement, displacement convergence hole body, rock pressure, tunnel arch structure internal force are measured and get the variation of displacement, internal force.Results analogy with field measurement results analysis, validation of this article developed materials, equipment, the reliability of the measurement program, a more complex conditions for subsequent studies laid the foundation.