Influence of slurry infiltration model on face stability mechanism |
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| Authors: | LI Yun ZHANG Zi-xin |
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| Institution: | 1. Key Laboratory of Geotechnical Engineering, Tongji University, Shanghai 200092, China;
2. Department of Geotechnical Engineering, School of Civil Engineering, Tongji University, Shanghai 200092, China |
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| Abstract: | During the excavation of tunnels in saturated soft soils, pressurized bentonite slurry is often used to support the tunnel face. The slurry should form a filter cake, which is used to transfer the support pressure onto the soil. This filter cake is constantly removed by the cutter head of the slurry shield and slurry will infiltrate into the soil while the filter cake rebuilds. This results in a decreasing of the support effectiveness of the slurry. To quantify the influence of these decreasing of the face stability, an infiltration model has been incorporated in a limit equilibrium analysis. The decreasing of safety factor of face stability according to the permeability of the soil in front is analyzed. The slurry pressure calculated with this model has been compared with field measurements. It is shown that the slurry pressure needed is significantly higher, compared with full-membrane calculations. |
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| Keywords: | slurry shield slurry infiltration model face stability slurry infiltration safety factor |
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