The Effects of End Platens, Method of Loading, and Specimen Size in Monotonic Triaxial R Tests.

The purpose of this research was to investigate the effect of changing certain test parameters associated with establishment of the critical void ratio using the monotonic triaxial R test. The parameters investigated include the effect of specimen size, method of loading ramp or step function, and end platens. The parameters which are usually held constant in the routine performance of critical void ratio determinations were investigated to determine their effect on the critical void ratio curve e sub f curve which is used to predict the liquefaction potential of a cohesionless material. The principal material used in this investigation was an Ottawa sand Banding sand. A reference e sub f curve was developed and compared to the previous established e sub f curve using Banding sand as determined by Castro. Test procedures and triaxial equipment were calibrated against Castros established curve. The parameters mentioned above were individually varied in the test program to determine what effect they had on the e sub f curve. The effect was determined by the relative vertical movement of the curve. The critical void ratio relationships resulting from the five test series were compared to the reference e sub f curve. It was concluded based on insignificant movement of critical void ratio curves that end platens, specimen size, and method of loading do not influence the critical void ratio determination.