Field Grouting Test of Modified Water Glass Reinforced Fine Sand Layerin Bored Tunnel
In the fine sand layer,frequent loosening and falling accidents occur during the construction of bored tunnels.A series of research work was carried out on diffusion characteristics,sand fixation performance,and tunnel excavation stability of modified water glass slurry inside the fine sand layer through indoor experiments,field infiltration grouting reinforcement experiments,and field grouting excavation experiments.The results indicated that:When the setting time of modified water glass slurry is controlled within 1～4 hours,it can effectively improve the shear strength of fine sand under low-stress conditions,and the unconfined compressive strength can reach 140～170 kPa.At a grouting pressure of 0.3～0.5 MPa,the modified water glass slurry formed a 60～80 cm thick sand consolidation body around the small conduit.This successfully suppressed the loosening and falling of the fine sand layer and provided a stable environment for bored tunnel excavation.The spacing between advanced ductile in the fine sand layer underground tunnel excavation should be controlled within 30～50 cm.The reasonable ratio of modified water glass slurry should be determined comprehensively through various methods such as indoor test selection,field slurry penetration grouting reinforcement test verification,and field excavation effect feedback.
bored tunnelfine sand layermodified water glass slurrygrouting reinforcement
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