# Method to Control the Deformation of Anti-Slide Piles in Zhenzilin Landslide
## 5 Discussion  
### Effect of the thickness of Lower Bedrock on the Deformation and Internal Forces of the Pile  
Pile deformation is as important as the internal forces in the piles, which must be considered for controlling a landslide [24; 31]. Various thicknesses of the first bedrock have an important impact on the deformation and internal forces of the pile.  
Figure 7a shows that when the thickness of the first soft bedrock increased from 0.5 to 2.5 m, the value of the maximum positive shear force of the pile was maintained at 9300 kN at the slip surface; the value of the maximum negative shear force of the pile increased by 20% from 11,494 kN to  
Figure 11: Relationship between the embedded ratio of pile and normalized pile-head displacement.  
13,718 kN, and the position of the maximum negative shear force was approximately 5 m below the slip surface. When the thickness of the first soft bedrock increased from 0.5 to 1.5 m, the maximum bending moment of the pile increased from 54,291 kN.m to 57,016 kN.m. However, when the thickness of the first soft bedrock increased to 2.5 m, the maximum bending moment of the pile became 55,782 kN.m, the position of which was approximately 2 m below the slip surface (refer to Figure 7b). When the thickness of the first soft bedrock increased from 0.5 to 2.5 m, the displacement of the pile top increased by 45% from 115 to 167 mm (refer to Figure 7c).  
The above comparisons show that when the embedded length of an anti-slide pile remains unchanged, the horizontal displacement of the pile and its maximum absolute shear force will increase with the increasing thickness of the first soft bedrock, which is disadvantageous to the safety of the control project. Because the crack width of the slope will increase with the increasing deformation of the pile head, groundwater will enter the slope along with the pile and increase the thickness of soft rock below the sliding surface, which will increase the shear force of the pile, resulting in possible cut off of the pile. In addition, water entry into the soil increases landslide thrust, which, in turn, increases the landslide speed, thereby casting a significant influence on anti-slide piles [19; 24].  
Effect of Subgrade Reaction Modulus of First Weak Bedrock on the Deformation and Internal Forces of Pile  
Groundwater enters the slope along with the pile, which not only increases the thickness of the soft rock below the sliding surface but also reduces the modulus of the subgrade reaction of the first weak bedrock. The modulus of subgrade reaction of the first weak bedrock (k\({}_{1}\)) significantly affects the internal force and deformation behavior of the piles.  
Comparison of Figures 8-10 shows that when the modulus of subgrade reaction of the first weak bedrock (k\({}_{1}\)) increases from 70,000 to 130,000 kPa/m with an embedded length of 8.5 m, the displacement of the pile top decreases by 11.3% from 123 to 109 mm; the maximum negative shear force decreases by 7.7% from 11,937 to 11,017 kN and the bending moment decreases by 3% from 54,291 to 52,689 kN.m. Increasing the value of k\({}_{1}\) will result in the maximum absolute value of pile internal forces and the displacement of the pile decrease. However, the magnitude of change is less than that of the results obtained for bedrock with upper hard rock and lower soft rock [31].