| The tunnel projects under construction and proposed in China are developing towards the trend of deep-buried,long-term and large-span.However,at present,there are a few engineering cases of using shield machine to construct tunnels in big cover depth,and the understanding of the influence of backfilling layer on the interaction between segment structure and surrounding rock under the condition of large cover depth is limited.Therefore,it has important theoretical value and engineering significance to study the influence of backfilling layer on the load and deformation of segment lining.Based on the Donghuan Tunnel of Guangzhou-Foshan Loop Line,this paper studies the internal force and deformation characteristics of the segments of shield tunnel with large cover depth by using the methods of data research,theoretical analysis,mechanics experiment of surrounding sock,numerical simulation and in-situ test to discuss the influence of backfilling layer of double-mode shield tunnel with large cover depth on the interaction between the segment structure and surrounding rock.The influence of the backfilling layer on the internal force,water and soil pressure of the lining structure is verified by in-situ test.The main work and research results are as follows:(1)The physical and mechanical parameters of rock mass obtained by triaxial compression test,the influence of the taper of the tunneling machine on the stress release of surrounding rock was analyzed by numerical simulation under different shield shell diameter and length,which provides a calculation method for stress release coefficient of subsequent numerical calculation On the basis of the above parameters,the numerical analysis which can reflect the whole stage of shield tunnel construction is carried out,and the influence law of the tunnel section size and buried depth on the loading and deformation of the segment is analyzed.(2)Based on the cellular automata theory,the corresponding code and software interface were written in combination with large mathematical software and finite difference software.The triaxial experimental numerical simulation of the backfilling layer of pea-gravel grouting was established to analyze the influence law of the content of pea-gravel on the strength of backfilling layer of pea-gravel grouting.(3)The influence of construction technology and material parameters on the interaction between segment structure and surrounding rock of the pea-gravel grouting backfilling layer adopted by Tunnel Boring Machine and the synchronous grouting backwall filling layer adopted by Earth Pressure Balance Shield Machine is studied respectively.(4)The spatial distribution of soil and water pressure,bending moment and axial force of segment structure during the construction of double-mode shield tunnel during the construction process of shield assembled,segment depart from shield tail,filling back of segment and stability stage of shield tunnel are analyzed.The model corresponding to the monitoring section is established by numerical simulation method,and the bending moment and axial force of the segment structure are obtained and compared with the results of the site measurement. |
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