Abstract:

The physical simulation experiment for mechanical behavior and sealing performance of tunnel structure under low vacuum condition is conducted base on the low vacuum pipe system platform, so as to explore the feasibility of tunnel structure in complex low vacuum environment. Some conclusions are drawn as follows: (1) The whole pipe wall is pressured due to annular force by vacuuming; the stress of outer wall is below 1 MPa; the stress of inner wall is greater than that of outer wall and is uneven due to the influence of inner airflow caused by vacuuming. (2) The axial force of pipe is between 60 kN and 200 kN, and the maximum bending moment is 1. 4 kN·m, which indicates that the pipe is in a state of large eccentric compression. (3) The higher the temperature in the pipe, the larger the leakage rate; the weak sealing points locate at the junction of embedded steel plate and concrete on both sides of pipe. (4) The structural deformation induced by low vacuum is small; in order to guarantee the sealing performance, the integral lining is recommended when the assembled tunnel segment structure is used in low vacuum pipe structure.

Key words: low vacuum, tunnel structure, physical simulation, sealing performance, mechanical behavior