# Static and Dynamic Response of Micropiles Used for Reinforcing Slopes
## 3 Results  
### Test Phenomenon  
The slope movement and crack propagation in the static model test and shaking table test are shown in Figure 9. The static model test was incrementally increased from 2 kPa, and when it was finally loaded to 28 kPa, the model had high deformation, and both the sliding bed and the sliding mass were misaligned, which caused the toe of the slope to move forward by 8.25 cm, and the top of the slope to subside by 7.8 cm. At this time, it was determined that the pile had entered the plastic failure stage, and the test was terminated. Figure 8: The layout of the test components (unit: mm). Figure 7: Layout plan of micropiles (unit: mm). It can be seen from Figure 9a that under the static load, the landslide body produced a circular arc rotation along the sliding surface, and the micropiles generated bending deformation near the sliding surface because of the landslide thrust. On the other hand, there was a void between the trailing edge of the connecting beam and the landslide body with cracks appearing at the toe of the slope. After the test, the micropiles were dug out from the model (Figure 10a). It was observed that the deformation occurred approximately 10 cm above and below the sliding surface (about three times the pile diameter). In terms of the degree of damage, the rear row piles were greater than the middle row piles, followed by the front row piles. In other words, the failure mode of the micropiles was mainly a bending failure under static loading due to the dislocation movement of the sliding mass and the sliding bed. The closer the piles were to the trailing edge of the landslide, the more serious the plastic failure. In the shaking table test, the landslide had no obvious change after being excited by an El-Centro wave with a peak acceleration of 0.1-0.4 g. After a peak acceleration of 0.6 g, a tension crack AB began to occur in the soil between the front row and the middle row of piles. The crack AB then extended downwards to point C with a width of around 0.8 cm. After the input of an El-Centro wave with a peak acceleration of 0.8 g, the slope started to slide, and the toe of the slope slid forward by 3.5 cm while the top of the slope settled 3.0 cm. At the same time, the crack ABC expanded to point D. The sliding mass continued  
Figure 10: Failure of micropiles (**a**) static model test; (**b**) shaking table test. Figure 9: Deformation and crack propagation of landslide model (unit: cm). to move, the toe of the slope moved forward by 8.45 cm cumulatively, and the cumulative settlement of the slope top was 7.93 cm. Finally, the crack penetrated to point E, cracks also appeared on the front side of the slope toe and the rear pile, the slope toe moved forward 11.7 cm horizontally, and the slope top settled at 9.0 cm when the test was terminated, as shown in Figure 9b. After the test, the micropiles were also dug out from the model (Figure 10b). In terms of damage degree, the rear row piles were approximately the same as the middle row piles followed by the front row piles. Comparing the static model test and shaking table test, the deformation of the model was relatively similar. The landslide body produced circular arc rotation damage along the preset sliding surface, and the micropiles generated a bent deformation near the sliding surface caused by the landslide thrust. There was a void between the trailing edge of the connecting beam and the landslide body. Compared to the static model test, the micropiles produced more serious damage under dynamic loading, but the failure mode was similar, all of which were a bending deformation about 10 cm above and below the sliding surface (about three times the pile diameter), as shown by corresponding tensile cracking and crushing of the plaster body. It can be seen that the damage to the pile mass under dynamic loading was more significant, so it is recommended to enhance the design requirements for micropile in a high-intensity field.