Abstract:

To explore the waterproof mechanism of sealing gaskets of segment joint from a microscopic view, the leakage channel model of the contact surface of sealing gaskets is established based on the Roth model to deduce the calculation formula of the leakage rate. Thereafter, the macroscopic sealing gasket numerical and microscopic conical peak numerical models are established to conduct the orthogonal test using the roughness, opening amount, dislocation amount, and hardness as the influencing factors, and the leakage rate and average positive pressure as the evaluation indexes. The main conclusions are drawn as follows: (1) The leakage rate can be used as an important index to evaluate the waterproof performance of sealing gaskets. (2) The leakage rate gradually increases as the roughness increases, and it increases exponentially when the roughness exceeds 0.8 μm. Hence, based on engineering cost, the recommended roughness of sealing gaskets ranges from 0.4 to 0.8 μm. (3) The roughness directly determines the size of the initial leakage channel; therefore, the influence of roughness on the leakage rate is the most significant compared with the effects of hardness, opening amount, and dislocation amount.

Key words: shield tunnel, segment, sealing gasket contact surface, leakage rate, numerical simulation, Roth model, gray relation analysis