Study On Force Characteristics Of Shield Segment In Sand Gravel Layer With Serious Leakage

Yellow River is the birthplace of Chinese civilization. As China’s second longest river, it is known for"changeable river, flood-prone" since time immemorial. Because of its specificity and uncertain riverbed the tunnel project constructed on the Yellow River is less, few have focused on the field of hydraulic engineering. Lanzhou Metro Line 1 is the first tunnel across the Yellow River and is used for rail transit as underwater engineering.Supported by Matan-Yingmentan metro section of Lanzhou Metro Line 1,laboratorial model test taking geometric similarity radio CL=10 bulk density similarity radio Cγ=1as the base is used as the research means to study the force characteristics of shiled segment in sand gravel layer with serious leakage.Below are the main research content and results:(1) based on the theory that barometric pressure is equivalent to hydraulic pressure, the uniform water pressure loading device is developed, which can simulate uniformly distributed pressure that tunnel segments bear. At the same time, with the use of horizontal loading test system, the loading process of hydraulic pressure and earth pressure completely separates. The results showed that, compared to the "hoop" and other traditional mode of hydraulic loading, the device is closer to the actual situation when uniformly distributed pressure that tunnel segments bear is simulated.(2) Based on beam-spring model, Using three-dimensional software ANSYS, the numerical simulation was carried out to study the impact of water pressure, lateral pressure coefficients and assembling methods on Internal Force, the results were compared with the scaled model test. The results showed that the two results were basically consistent, indicating correctness of the model test results.(3) On the basis of scaled model tests and numerical calculations, the force characteristics of shiled segment in sand gravel layer with serious leakage were summarizes systematically the water pressure conditions, the vertical soil pressure, soil lateral pressure coefficient and assembling methods was different conditions...