In this discussion of the originial paper, attention is directed towards the boundary conditions adopted for the experimental examination. It is noted that at an undrained anode, where the pore-water pressure goes into tension, if gas is introduced into the system, the gas will expand to accommodate the tension, resulting in virtually zero tension in the pore water during the early stages of testing. Various reactions at the electrodes are likely to decrease the rate of gas production and electro-chemical change so that pore water tension at the undrained anode is able to increase but not as described by the diffusion equation. Experience shows that in order to overcome these deviations from the state discribed by the diffusion equation, the experimental equipment has to incorporate special electrodes that remove the influence of the anomalies, to that pore-water pressure change is the only product of the electric potential applied to the soil. The electrode systems used make use of a property of the silicon-rubber memberane that is permeable to gases but not to liquids. In addition, an efficient monitoring system is employed to maintain a constant voltage across the soil under test and not merely between the electrodes. By measuring the pore-water pressure response at the undrained electrode and at a variety of intermediate points, a comparison between theoretically and experimentally derived results could be made. A second discusser observes that invariably the soil medium would possess a certain amount of electroloytic material in the pore water that facilitates the flow of current in the medium. If the concentration of such an electrolyte is considerable, then the electro-osmotic effict is retarded very much. Thermodynamic and other time-dependent changes would taken place inside the soil medium because of electrical energy input. There would also be considerable changes in the ph near the electrodes. Comments are made on the electrode reversal technique, and it is noted that thermodynamic effects and electochemical reactions will have to be incorporated in the analysis.

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  • Accession Number: 00156161
  • Record Type: Publication
  • Report/Paper Numbers: Proc. Paper 12156 Proceedin
  • Files: TRIS
  • Created Date: Feb 16 1978 12:00AM