# Study on the Optimization of Pile Length of Micropiles in Soil Landslides
## 2 Methods
### Optimization of Micropiles Length Based on Numerical Simulation
#### 2.4.3. Programmatic Implementation of Optimization Algorithms
In the program implementation, once the relative position between the unit-forming nodes and the stratigraphic line is recognized in programming, it becomes straightforward to identify these nodes requiring division into wedge-shaped elements and accomplish unit composition for the entire model. After the unit composition, the constructed units can be grouped according to the stratigraphic boundaries. For ease of operation, the geometry geological interface grouping technology built into numerical simulation is used for rapid grouping. Specific operations can refer to the numerical simulation technical manual. After completing these four key steps, it is possible to directly generate a numerical simulation calculation model from the profile map. With corresponding programming operations, this process has a high degree of automation and can achieve one-button modeling. This rapid modeling technology also overcomes the complex obstacles of modeling for optimization solving using the finite difference method with numerical simulation software. Generation of numerical simulation calculation commands  
To further ensure the engineering feasibility of the optimization program and reduce the difficulty of writing numerical simulation optimization command streams for different landslide forms and parameters, command streams that can be used for optimization calculations are automatically generated. Based on the calculation results mentioned earlier and the parameter transmission, this study uses an Excel spreadsheet to assign basic numerical simulation parameters and then reads these data through a program, combining the results of parameter transmission to generate numerical simulation calculation command streams for initial stress balance calculation, initial slope stability calculation, and pile stability calculation. Analysis and presentation of optimization results  
The optimization solution process described in the previous section obtains a table of corresponding pile lengths and safety factors. After achieving convergence, the internal forces of the pile can be extracted and analyzed under the optimal working condition corresponding to the converged solution, facilitating automatic graph generation. This result is the internal force distribution result obtained by numerical simulation analysis. In practical operation, it can be compared with the results obtained by theoretical calculation, and if necessary, the larger value can be taken as the design value of the structural internal force. Example Analysis  
The selected example is a typical landslide behind a plant in the northwest region, with a slope width of about 160 m, a length of about 95 m, and a height difference of about 32 m between the front and the back edge. Slip material for the original slope area of the slope surface residual slope deposits and the overlying Loess landslide form is more obvious, with a slope of about 15\({}^{\circ}\)-25\({}^{\circ}\). According to survey data, the stratigraphic parameters are taken as shown in Table 4. The characteristic period of the ground vibration response spectrum within the project area is 0.35 s, with a design basic seismic acceleration value of 0.15 g and corresponding seismic intensity at level VII. According to the stability calculation based on the parameters provided by the survey, the results show that the stability safety coefficient of the slope body is only 1.03 in the natural state, less than 1.0 in the saturation condition, and less than 1.05 in the earthquake condition. Its stability level is poor, and engineering treatment is urgently needed. Considering the relatively modest annual rainfall in the project area and favorable natural drainage conditions surrounding the slope, achieving full saturation becomes challenging. Therefore, engineering calculations are conducted using parameters representative of the natural state.