Assessing clogging potential and optimizing driving parameter of slurry shield tunneling in clay stratum assisted with CFD-DEM modeling

This paper proposed a two-way coupled computational fluid dynamics(CFD)and discrete element method(DEM)approach to analyze the evolution of clogging in slurry shield tunneling quantitatively.The interactions between clay particles and slurry were considered by exchanging three interaction forces,including buoyancy force,pressure gradient force,and drag force.The CFD-DEM coupling approach was first benchmarked by comparing cutterhead torque and total thrust with field monitored data of a practical slurry shield tunnel project.The evolution process of the particle phase and the fluid phase over time was presented.The results indicated that fewer than 70%of the particles can be washed away in time by the circulating slurry.About 9%of the particles adhered to the submerged wall,resulting in increased cutterhead torque and thrust.Through parametric analysis,the influence of the shield driving parameters on the clay clogging behavior is further explored.The time history of cutterhead torque or thrust can be used as a criterion for judging whether clogging has occurred.Additionally,a new assessment method of clogging risk and an optimization strategy of driving parameters were proposed,which were intended to provide some guidance for similar projects.

Dissolution of antibiotics mycelium in ionic liquids:Performance and mechanism

Antibiotics mycelium, byproduct of pharmaceutical industry, contains high percentage of proteins, polysaccharides and lipids, while, the low solubility in traditional solvents limits its utilization. The dissolution process of penicillin mycelium was investigated using ionic liquids （ILs） as solvent. Quantitative correlation of solubility and ILs structure and dissolution mechanism were determined. About 91 45% of penicillin mycelium was dissolved in 1-butyl-3-methylimidazolium acetate （[Bmim]Ac） under the condition of 120.0℃C and [Bmim]Ac/ mycelium （m/m） ratio of 3.90：1. Synergistic effect of ILs and DMSO was confirmed with the DMSO/[Bmim]Ac （v/m） ratio in the range of 0.0-1.0. At 25.0 ℃, the dissolution of penicillin mycelium increased from 69.74% to 94.50%, with the ratio of DMSO to [Bmim]Ac （v/m） as 1：1. The room temperature dissolution of mycelium provides a novel and energy-saving process for its high-valued utilization. The NMR and FT-IR spectra showed that hydrogen bonds are the dominant driving force for the dissolution in ILs. Quantitative study on the effects of anions and cations of lLs on dissolution using Kamlet-Taft model showed that there was a linearly positive correlation between solubility of penicillin mycelium and β parameter of the ILs. The solubility of mycelium increased with increasing hydrogen bond accepting ability of anions and donating ability of cations.