Research On Rheological Properties And Deformation Control Technology Of Surrounding Rock In Tuff Formation Large-section Tunnel

Based on construction of Sanlian tunnel in tuff ground in Liuzhan double tracking railways, this article studies on the physical and mechanical properties of tuff formation,and discusses the mechanism, classification and control Technology of large deformation in large-section and tuff tunnel by means of field investigations, indoor tests, field monitoring and numerical simulation.The main research contents and results in this paper are as follows:(1) By field monitoring and tests, this paper studies on the large deformation mechanism of tuff stratum, which shows that the most prominent characteristics of Sanlian tunnel in tuff formation are long time of lasting deformation as well as large-scale deformation, and horizontal convergence is larger than corresponding crown settlement.(2) Based on experiments of physical properties,triaxial compression tests and tiaxial creep tests, the corresponding parameters of tuff are obtained. The results of indoor tests indicate that tuff in Sanlian tunnel is a type of rock with obvious rheology, and H-K model can describe the creep characteristics of tuff appropriately.(3) Two mehods are adopted to simulate the large deformation of tuff ground, one takes the rheology of tuff into consideration while another not. The simulation results show that the former is more close to the real condition, which verifies the suitability of H-K model.(4) It studies the combined action mechanism of surrounding rock and supporting structure, and presents reserved deformation and its control standard with different rocks. Besides, Comprehensive coefficient method is adopted to determine the classivication of large deformation in Sanlian tunnel, and the relevant prevention and treatment measures for different-level large deformation are presented.The study results mentioned above have been applied in construction of Sanlian tunnel in tuff stratum, which ensures the construction safety and quality of the tunnel structure effectively, and provides some guidance for silimar engineering in future.There are41pictures,31tables and100references in this article.