| With the continuous growth of China’s economy,the process of urbanization continues to advance,and the urban population continues to increase,more and more major cities have begun to build subway.Due to the characteristics of less pollution,efficiency,safety and strong adaptability to the ground,shield method is widely used in urban subway construction.As a key process of shield method,the effect of synchronous grouting directly affects the construction quality and safety.In the present thesis,the synchronous grouting filling pattern is considered.Aiming at quantitatively describing the process of grout diffusion and the influence of synchronous grouting and ground grouting on ground deformation,the distribution of grout pressure with different grout in the process of synchronous grouting and the influence of synchronous grouting under different tunnel buried depth and ground grouting on ground stress and displacement are studied,based on theoretical analysis and test-in-place.Due to the uneven time-spatial distribution of viscosity of binary slurry and time variation of viscosity of simple grout,the space-time distribution equation of viscosity,grout pressure equation under filling pattern of binary slurry and different simple grout is deduced by the theory of fluid mechanics and the diffusion model of synchronous grouting filling pattern.And then the general formula is summarized.Finally,the results from the theoretical analysis,test and existing study are compared,the regular pattern of grout pressure under filling pattern is further revealed.In order to study the influence of grout pressure on ground deformation of synchronous grouting,formulas of ground stress and displacement suitable for deep shield tunnel are deduced by using the theory of cylindrical cavity expansion and establishing mechanical model.Then,for the case that the formulas are not suitable for the shallow buried shield tunnel in the semi-infinite space,the formulas of vertical and horizontal displacement of the ground under the semi-infinite space suitable for the shallow buried shield tunnel are obtained by using the image method to modify the surface stress.Finally,an engineering example is analyzed,the results show that the significantly apparent disturbance influence of the sensitive buildings under the action of the synchronous grouting when the shield passes through sensitive buildings,effective construction measures such as ground grouting should be taken to control the disturbance.Ground grouting is a common reinforcement measure to control the disturbance in shield tunnel construction.In order to analyze the influence of ground grouting on the ground deformation when the compression effect is dominant,the formulas of stress and displacement in the plastic and elastic area of soil are derived based on the theory of spherical cavity expansion.Considering the difficulties of engineering application,the theoretical relationship formula among the expanding pressure p,initial radius a0 and expanded radius a was derived by the conservation of mass and the mean volumetric stain expression in plastic zone.The problem of spherical cavity expansion can be solved directly according to the known value of the engineering.In order to study the specific influence of design parameters and construction parameters on the ground deformation and provide basis for the selection of design parameters and construction measures,the radial stress,circumferential stress and radial displacement of the ground in the elastic and plastic zone around the grout under different yield criteria,dilatancy angle,grouting pressure and grouting penetration pressure are calculated respectively.The selection criteria of yield criteria and dilatancy angle are clarified,the law of disturbance of grouting pressure and grouting penetration pressures on ground is revealed,and the corresponding control measures are proposed. |
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