FLUID-STRUCTURE INTERACTION ANALYSIS OF SHIELD TUNNELS CROSSING SATURATED SAND LAYERS
During the crossing of sand layers by interval shield tunneling,high water content and significant permea-bility in the sand layers can lead to sudden water influx and sand eruption incidents.This study utilizes the finite ele-ment method to analyze the stress characteristics of the soil and lining structures after the completion of a dual-line shield tunnel under saturated seepage conditions.The results indicate that after the excavation of the left-line tun-nel,the horizontal stress within the grouting layer is greater than in the non-grouted areas,causing extrusion flow and upward arching at the tunnel bottom.Ground settlement above the right-line tunnel is less than that above the left-line tunnel,and the strength and bearing capacity of the surrounding soil decrease.During actual construction,it is essential to prevent excessive upward stress on the lining crown and bottom.Appropriate reinforcement and sup-port measures should be implemented at different arch waist locations to increase the support strength of the portal section,ensuring the stability of the structure.
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