Clogging frequently occurs in the cutter head,excavation chamber or screw conveyor when an earth pressure balance(EPB)shield machine is tunneling in soft or silty clay ground with high clay mineral content.In this pap...Clogging frequently occurs in the cutter head,excavation chamber or screw conveyor when an earth pressure balance(EPB)shield machine is tunneling in soft or silty clay ground with high clay mineral content.In this paper,montmorillonite,kaolinite,and illite were selected as research objects,and molecular dynamics simulation and laboratory experiment were adopted.At the microscopic scale,dynamic contact behavior and interfacial mechanical behavior of the interface between clay minerals and water/surfactant solution was simulated and the interfacial adhesion and conditioning mechanism between clay minerals and water/surfactant solution was revealed.Thus,sodium dodecyl benzene sulfonate surfactant was selected as the main composition of the soil conditioner.Then,the adhesion stress before and after soil conditioning and the contact angles between clay minerals and water/surfactant solution were tested and analyzed at the macroscopic scale.The result shows that the contact angle between droplet and clay mineral surface is an important parameter to characterize soil adhesion.The simulation rules of the microscopic contact angle are consistent with the experiment results.Furthermore,the adsorption energy between microscopic substances is dominated by electrostatic force,which can reflect the adhesion stress between macroscopic substances.Soil adhesion stress can be effectively decreased by adding the surfactant to the soil conditioner.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52078428)the Sichuan Outstanding Young Science and Technology Talent Project(Grant No.2020JDJQ0032).
文摘Clogging frequently occurs in the cutter head,excavation chamber or screw conveyor when an earth pressure balance(EPB)shield machine is tunneling in soft or silty clay ground with high clay mineral content.In this paper,montmorillonite,kaolinite,and illite were selected as research objects,and molecular dynamics simulation and laboratory experiment were adopted.At the microscopic scale,dynamic contact behavior and interfacial mechanical behavior of the interface between clay minerals and water/surfactant solution was simulated and the interfacial adhesion and conditioning mechanism between clay minerals and water/surfactant solution was revealed.Thus,sodium dodecyl benzene sulfonate surfactant was selected as the main composition of the soil conditioner.Then,the adhesion stress before and after soil conditioning and the contact angles between clay minerals and water/surfactant solution were tested and analyzed at the macroscopic scale.The result shows that the contact angle between droplet and clay mineral surface is an important parameter to characterize soil adhesion.The simulation rules of the microscopic contact angle are consistent with the experiment results.Furthermore,the adsorption energy between microscopic substances is dominated by electrostatic force,which can reflect the adhesion stress between macroscopic substances.Soil adhesion stress can be effectively decreased by adding the surfactant to the soil conditioner.
