Study On Mud Fluid Properties For Cutting Face Stability Of Slurry Shield In Sand Gravel Layer

With the variety of urban function and engineering techniques advance rapidly, rapid transit connected by tunnels has become an important way of communication and exchange between cities and areas. Recently, with the economic development ,more and more large sea and river crossing shield tunnel construction have been built at home and abroad by slurry tunnel machine.The large-diameter tunnels have been one of development directions in tunneling engineering. Large slurry shield machine has been widely used in China at present. But there is still some problems on the control of the cutting face stability ,especially the mud fluid properties which play an important role in face stability are seldom studied. Therefore researching the slurry characters and the influence of infiltration to the face stability is of signifigence.Based on theoretical analysis and indoor test, according to engineering properties of sandy cobble stratum, from excavating face stabilization and removal of the excavated material, mud fluid properties and influence of slurry infiltration to the face stability were researched, a series of achievements were obtained.Firstly, designed an apparatus that can simulate slurry seepage in sandy cobble stratum.Secondly, aiming at characteristics of sandy cobble stratum, considering equipment capacity of slurry system and referring to the tunneling examples of slurry shield in the stratum of sandy gravel, reference values of slurry properties indexes were put forward.Thirdly, the influence law of slurry relative density, viscosity, seepage differential pressure to slurry seepage and formation of mud cake were obtained by experiments.Fourthly, studied the impermeability of slurry cake through the experiments, obtained the influence of the penetration time and seepage pressure to the impermeability of mud cake.Finally, got the seepage parameters of slurry in sandy cobble stratum by the results of permeation experiments; calculated the slurry pressure reduction and safety factor of the cutting face stability with infiltration mode.