# Field Pull-Out Tests of Percussion Driven Earth Anchors (PDEAs)
## 5 Results and Analysis  
### Field Pull-Out Test Results  
According to Platipus Anchors Brochure [31], the load-displacement curve for the pull-out test typically goes through three major stages. The first stage is the repositioning and load-locking stage, where the anchor repositions to a horizontal position when subjected to pull-out loads. This stage typically occurs at lower loads of up to 2.2 kN, as observed in this study. The second stage of the pull-out test includes more loading and compaction of soil above the anchor. This stage produces high resistance while the anchor is subjected to pull-out loads. This second stage continues until the anchor reaches the ultimate resistance based on the soil conditions. In practice, the working load usually lies in this stage close to 75% of the ultimate resistance. The third and last stage brings the anchor to failure by bearing capacity due to the strength of the soil with respect to the anchor type. For this study, the anchor pull-out tests were plotted based on the load and displacements measured using the load cell and LVDT, respectively. Four field pull-out tests were employed on the west slope. The performance of each anchor was evaluated in different field conditions. Table 2 summarizes pull-out test results, including the maximum pull-out load and displacement for each tested anchor. One of the anchors, anchor 3, was installed and tested near the northwest quadrant of the channel bank slope. It was subjected to pull-out force until the maximum pull-out resistance was achieved. This anchor was tested in five loading strokes. Figure 11: Illustration of PDEA anchoring and testing process: (**a**) anchor driven, (**b**) pullout test setup, (**c**) pullout test (anchor rotation), and (**d**) anchor locking and finish surface of slope. Additionally, this anchor testing was used as an example to illustrate the behavior of each stroke and the stroke combination process. Figures 12 and 13 depict each stroke's load, displacement response, and the combined stroke curve. The first stroke, shown in Figure 12, subjected the anchor to repositioning and load locking. Then, the anchor shifted to the compaction and loading stage at around 2 kN load and stayed in that stage. The maximum load achieved by stroke 1 was 8.79 kN over 7.6 cm displacement. The second stroke experienced the compaction and loading phase and reached a maximum load of 8.8 kN over 7 cm displacement. The behavior of the anchor during the third stroke was similar to that in the second stroke, except that the third stroke achieved a higher load over a smaller displacement (12.76 kN over 5.6 cm displacement). Figure 12 also shows that the fourth stroke experienced the compaction phase and reached the ultimate pull-out strength of 17 kN over the 9 cm displacement. This stroke also showed that as the load decreased from the ultimate value, it experienced bearing capacity failure. In the last stroke of this test, stroke 5 regained the load up to around stroke 4's last load and then continued to decrease toward failure. The individual strokes were further processed to be merged into one continuous anchor-response pull-out curve to obtain the ultimate load and the corresponding maximum displacement. The curves for each stroke were combined using the following process. Stroke 1's curve was held as the foundation of the combined curve and kept the same as the original shown in Figure 13. The curve from stroke 2 was shifted to the left until it reached stroke 1's curve. The data from stroke 2 that were lower than the maximum displacement of stroke 1 were omitted. This process was repeated for all strokes to produce one continuous anchor-response load-displacement curve. Figure 12 illustrates the combined force-versus-displacement graph for the anchor 3 pull-out test. The ultimate pull-out resistance and corresponding maximum displacement from this test were found to be \(\mathrm{P}_{\mathrm{ult}}=17\) kN and 20.6 cm, respectively. Anchor 2 was tested twice to reach the ultimate pull-out strength.