Suction controlled wetting tests

Two oedometer tests following the same wetting under load path were performed on identical samples, using different techniques. A special oedometer cell was designed and built in order to perform the tests. The cell may handle two suction control techniques vapour equilibration and liquid water transfer. In the second case an axis translation procedure may be introduced by nneans of gas and water pressure controls on the upper and... 

Figure 4. Stress path followed in wetting and loading tests under controlled suction at different temperatures.

Now we need to make a choice how to control the pressure Pr and the pressure difference APrr. It is obvious that gas flows will be the proper choice to control pressures. Therefore the possible candidates are the stack gas flow valve Fj dt and the wet gas compressor suction valve Vproducp A step disturbance of-5% was given in Vproduct and +5% in The changes in APrr and Pr were monitored and the absolute value of the process gain was estimated from the tests. The results as shown in Table 35.2 were obtained (percent change divided by per cent change). 

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