# Study on the Optimization of Pile Length of Micropiles in Soil Landslides
## 1 Introduction
[PERSON] [11] investigated the correlation between the peak moment and embedment ratio (the ratio of the embedded section to the length of the loaded section) of piles and derived a critical embedment ratio for lateral rigid movement. This critical value represents when piles undergo lateral stiffness movement. [PERSON] [12] studied the embedment depths of 1/4, 1/3, and 2/5 pile lengths in pile swelling soil landslide prevention and control by physical model tests, and the results showed that the foot slope and pile top displacement tend to decrease as the embedment depth increases, and the embedment depth of a 1/3 pile length is more suitable. [PERSON] [13] et al. used the strength discount finite element method to analyze several factors affecting the stability of slopes reinforced by anti-slip piles and obtained the optimal design elements of anti-slip piles, such as optimal pile position and critical pile length, which provide a reference basis for the optimal design of a row of piles and established the deformation prediction mathematical model, which provides a reference basis for the deformation control of the pile body. In order to reduce or eliminate the deformation of high-speed railroad foundation bulge, [PERSON] [14] et al. carried out the actual engineering cases and designed key parameter research studies based on the wet-dry test of the Yungui Railway foundation bed and improved the traditional minipile into a kind of anti-uplift long and short minipile structure. It is recommended to use \"small pile diameter, small pile spacing\" long and short micropiles to reinforce the ballasted railroad foundation base expansion soil. [PERSON] [15] et al. proposed a linked iterative algorithm for pile length optimization under seismic loading, which accurately calculates the optimal pile length for friction pile foundation of bridge abutment and provides a reference for the optimal design of pile foundation structure for railroad bridges. [PERSON] [16] et al. took gray soil pile reinforcement of large quasi-heavy railroad roadbed as the engineering background and researched the influence of factors such as pile shaft inclination, pile diameter, pile distance, and pile length on the effect of gray soil pile reinforcement of existing railroad roadbed with the help of finite element software. It provides a theoretical basis for the engineering design and safety evaluation of gray soil pile-reinforced existing railroad roadsbeds. [PERSON] [17] et al. applied large-scale finite element numerical analysis software to establish a numerical analysis model based on the field model test and under the condition of basic assumptions. Upon adjusting the parameters of pile length in the pile raft foundation, the pile length was optimized. Based on numerical simulation software, [PERSON] [18] et al. set up a numerical model for mechanical analysis to select the reasonable location of multiple rows of anti-slip piles and compare the design parameters of Rizheng software with collected data to determine the optimal values of pile spacing and anchoring depth and apply them to the engineering examples for verification. The analysis concludes that this optimization design method is feasible and practical and can provide a reference for subsequent landslide management. [PERSON], [PERSON] [19] et al. optimized the structural parameters of h-type anti-slip piles using numerical software, which showed that the optimum beam stiffness was three times the front and rear piles, the optimum rear pile depth was 0.28 times the length of the rear pile, and the depth of the front pile was 0.5 times the length of the front pile. [PERSON], [PERSON] [20] et al. performed numerical calculations using PLAXIS 2D and 3D to optimize a row of piles in cohesive friction slope reinforcement. The results show that fixed pile heads located in the middle of the slope provide better stability and reduce the optimum length of the piles. [PERSON], [PERSON] [21] et al.