Field tests on behavior of destructive and non-destructive base-grouting piles under compression

Field tests on the behaviors of one destructive base-grouting pile and one non-destructive base-grouting pile under compression are presented. The two piles have different diameters and are instrumented with rebar strain gauges along the pile shafts. The results of these full-scale loading tests show that the ratio of the tip load to the pile head load of the destructive and the non-destructive base-grouting piles is about 40% at the capacity load level, and it decreases with the increase of pile diameter at the same load level. Furthermore, at shallow depth the skin friction of the non-destructive pile decreases from the ultimate skin resistance with the increase of load as the test pile is loaded to the maximum value, whereas for the destructive pile the shaft resistance along the pile depth approaches to the limiting state and decreases from a peak value with further increase of the pile head load. The thresholds of settlement at the pile head for fully mobilizing the skin resistances in different soils are about 1% to 4% of the pile diameter. The load transmission curve of the soils around the pile base corresponds to a softening model in the field tests on the destructive pile, whereas the settlement-resistance curve of the non-destructive pile developed at the pile tip follows a hardening model.