Experimental Study on Long-Term Deformation Characteristics of Deep and Thick Fills in Giant Karst Cave
In order to explore the variation of settlement and stress of the karst cave backfill and natural accumulation layer at different depths,a giant karst cave backfill project in the Yujingshan tunnel of Chengdu—Guiyang railway was studied.A 1∶100 laboratory centrifugal model test was carried out to analyze the long-term deformation law of the inhomogeneous natural soft accumulation layer at the bottom of the karst cave,in which the river sand with a particle size of less than 2 mm was used to simulate the karst cave backfill,and the western Sichuan clay was used to simulate the soft soil layer at the bottom of the karst cave.The reliability of the laboratory test was verified by field monitoring results.The results show that the deformation of the karst cave backfill basically reaches a stable state within 1.5 years after the termination of construction,and the deformation is about 86.9%of the total settlement;the deformation of the soft soil layer is the main component of the soil deformation at the bottom of the tunnel,and its deformation accounts for about 87.5%of the total settlement.The settlement at the bottom of the tunnel is positively correlated with the thickness of the soft soil layer,and when the thickness of the soft soil layer is less than 12.5 cm,it has less influence on the settlement at the bottom of the tunnel.The difference in settlement deformation between the model test and the on-site monitoring is only 3.83%,indicating that the experiments conducted in this article can reflect the long-term deformation characteristics of the soil at the bottom of the tunnel.
deep and thick fillslong-term deformationcentrifugal model testinhomogeneous soft layeron-site monitoring
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