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Experimental Study of Soil Conditioning with Foam for the Shield Tunnel in Composite Stratum
(1 School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070；2 China Railway 20th Bureau Group Corporation, Xi′an 710016)
Abstract Blow-out, mud cake, high torque of cutterhead and serious wear of cutting tools could be encountered during long distance shield driving in the composite stratum. A foam based soil conditioning experiment was carried out by a self-made foam generator, and the variations of various physical parameters of soils of completely weathered stratum, composite stratum or strongly weathered stratum under different injection rates of foam were analyzed. The results show that the permeability coefficient, cohesion and internal friction angle of soils could decrease effectively by foam injection; the permeability coefficient may decrease to 10-6 m/s by the foam with injection rate of 20%, meeting the requirement of permeability resistance of shield tunnel construction; the optimal foam injection rates meeting the requirement of“plastic flow”of soil mass under ideal condition are 30%, 10% and 10% respectively during shield construction in strongly weathered stratum, composite stratum and completely weathered stratum.
Abstract：
Blow-out, mud cake, high torque of cutterhead and serious wear of cutting tools could be encountered during long distance shield driving in the composite stratum. A foam based soil conditioning experiment was carried out by a self-made foam generator, and the variations of various physical parameters of soils of completely weathered stratum, composite stratum or strongly weathered stratum under different injection rates of foam were analyzed. The results show that the permeability coefficient, cohesion and internal friction angle of soils could decrease effectively by foam injection; the permeability coefficient may decrease to 10-6 m/s by the foam with injection rate of 20%, meeting the requirement of permeability resistance of shield tunnel construction; the optimal foam injection rates meeting the requirement of“plastic flow”of soil mass under ideal condition are 30%, 10% and 10% respectively during shield construction in strongly weathered stratum, composite stratum and completely weathered stratum.
ZHOU Jixue1,
2
.Experimental Study of Soil Conditioning with Foam for the Shield Tunnel in Composite Stratum[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(4): 194-199
2019, Vol. 56 