Research On Shield Tunnel Synchronous Grouting Pressure Distribution Patterns And Stratum Deformation

With the rapid development of urban construction in our country, the subway construction is an important part of urban underground space development in the 21 st century. Shield method due to its advantages has become a play an important role in the urban subway construction, but the shield construction inevitably causes ground movement and deformation, and shield tail synchronous grouting for control of soil disturbance and stratum deformation is very effective. So this thesis of synchronous grouting pressure distribution model and study the stratum displacement caused by expansion.In order to study the synchronous grouting pressure distribution model, this paper respectively to accord with Newton flow and Bingham flow type two kinds of slurry pressure distribution theory is derived, ring to the theoretical calculation formula of pressure distribution are obtained. In this paper, the relationship between viscous coefficient and time was deduced grout pressure dissipation law of change over time, and then established the serous longitudinal pressure dissipation law, and through the field monitoring illustrates the rationality of the theoretical derivation and correctness. Then focus on analysis of soil mass is derived obey the M-C yield criterion under homogeneous grouting pressure and the law of the soil between the radius of plastic zone.Established through the study of the grouting pressure distribution model, using the large finite element software Midas/GTS of Che-Nong and Che-Xiang in Shenzhen subway shield interval shield excavation engineering, mainly consider the grouting pressure ring to the distribution patterns and longitudinal pressure dissipation model, for the whole construction process of shield tunnel excavation, 3D virtual simulation system analysis in the process of shield tunneling grouting pressure distribution model, synchronous grouting time constraints such as generation of layer thickness and thrust, the influence law of stratum displacement. through the analysis found that the non-uniform distribution patterns of grouting pressure, the greater the degree of surface subsidence of the more significant, the tunnel roof soil subsidence, and negatively related to the quantity of soil layer at the bottom of the uplift, grouting is not in a timely manner will result in surface subsidence is increased, compared with timely settlement of grouting rate up to 26.7%. Generation such as the increase of layer thickness in a certain range can significantly reduce the cross-sectional surface subsidence, Constraints force within a certain range can significantly control the longitudinal surface deformation, and the shield tunneling of the surface settlement range is about the influence of the longitudinal cutter cut 20-30 m, before and after shield machine cutter cut 25 to 40 m.This article end through static analysis to explore different pressure distribution on the segment internal force and deformation mechanics effect, and grouting pressure distribution form analysis is made on the segment large effect on axial force and shear force. for the segment deformation and bending moment influence is relatively small. To sum up, this article research results for subway shield tunnel working condition of synchronous grouting the guidance and reference significance.