# Study on Shielding Effect of the Pile Group in a Soft-Soil Foundation
## 3 Results  
### Displacement Analysis  
Figure 5 depicts the variation in the lateral displacement of the soil along the A-A\({}^{\prime}\) profile during the sequential installation of three rows of hydrostatic piles. As the three rows of piles are successively installed, the displacement off both sides of the pile group increases. The lateral displacement curve takes a parabolic shape, where smallest values appear at the bottom and larger values appear in the shallow ground. Following the installation of the first row of piles, the left region experiences a significant increase in displacement, while the right region only has a minor increase in displacement. After the installation of the second row, the displacement in both sides increase, with the displacement on the left side being greater; even so, the displacement increase caused by the second row of piles is noticeably smaller on the right side. After the third row of piles is installed, the accumulated displacement on the right side exceeds that on the left. This indicates that the first and second rows of piles effectively controlled the deformation of the left side, namely the shielding effect. Figure 4: Pile group installation sequence and layout of monitoring profiles. To quantify the response characteristics of the shielding effect in the displacement field, a comparison study was conducted between the \"actual accumulative displacement\" of single-row piles considering the shielding effect and the \"superimposed accumulative displacement\" without the shielding effect. After the installation of three rows of piles, monitoring point A (see Figure 6b) was established at a distance of 2.5 m from the left side of the first row of piles, and the horizontal displacement of the soil at this location, defined as the \"actual displacement\", was measured. Since the distances from the first, second, and third rows of piles to point A are 2.5 m, 5.0 m and 7.5 m, respectively, the superimposed accumulative displacement could be acquired by summing up the displacement obtained at individual rows (Figure 6a,c-e). Comparing the two displacement types revealed that the superimposed accumulative displacement was 21.43% greater than the actual accumulative displacement (Figure 6f). Further, dynamic disturbance characteristics of soil as well as existing piles during the sequential piling were investigated, regarding both the magnitude and direction of the disturbance. In Figure 7, monitoring points were set to dynamically track the displacement trajectories of the pile heads (circles) and the ground surface soil (rectangles). Specifically, the red circles represent the undisturbed pile head, and the black circles indicate the updated pile positions after the installation of each new pile. Similarly, the blue rectangles represent the undisturbed soil positions, while the black ones indicate the track of the soil after each pile was installed. Notably, these trajectories have all been visually amplified so that the variations can be seen clearly. The results demonstrate that each penetration of pile induces a directional disturbance both on the soil and piles. Given the sequential installation of the piles from the W direction to E direction, the pile head trajectories go towards the W direction. For the soil, the final displacement at point A in the W direction is 32.55 mm, which is smaller than the lateral displacement of 33.92 mm at point B in the E direction. After the first row of piles was driven, point A experienced significant displacement, while the installation of the subsequent two rows of piles resulted in obviously smaller displacement; for point B, the displacement caused by the first row of piles was not  
Figure 5: Displacement contour maps along A-A’ profile during sequential installation of three rows of hydrostatic piles. large, but the displacement caused by the third row of piles was significant. The final displacement of point A was smaller than that of point B, indicating that a shielding effect was formed for point A given this piling sequence.