## 7 Analysis of Optimizing the Foundation Pit Supporting System Based on the Space Effect  
It can be identified through the research above that conventional supporting methods have certain disadvantages in controlling the deformation of retaining piles, especially when the slip surface is uncertain. Narrowing the spacing of retaining piles will remarkably increase the supporting cost and construction period, but the greater the excavation depth of foundation pit, the more obvious the space effect [27; 28]. Therefore, this paper attempts to adopt the spatial effect-based sectionalized support control technique to artificially construct a dense space to improve the engineering efficiency and support effect, avoiding the influence of weak structure on the overall stability of rock mass [29]. As shown in Figure 23a, the retaining piles on both sides of the reinforcing point are deleted based on the original layout of a pile spacing of 3.0 times, forming the layout mode of \"dense in the middle and sparse on both sides\". When a combination of zoning and sparse-dense piles is adopted, the middle piles and side piles on the bedding rock side and the toppling rock side deform almost synchronously, as shown in Figure 23b. This indicates that the remaining sliding force of the entire rock mass is concentrated in the middle of the divided area and that the deleted retaining piles on both sides of the reinforcing point have no influence on the overall supporting effect. Figure 22: Trend table of horizontal displacement variations for various calculation methods. Figure 23: Stress analysis of sectionalized support system (design of sparse-dense pile). (**a**) schematic diagram of sectionalized sparse-dense pile support model (Unit: m); (**b**) displacement of retaining pile; (**c**) displacement of pile body at reinforced point (bedding rock side); (**d**) displacement of pile body at the reinforced point (toppling rock side). At the reinforcing point, the tops of the four reinforcement piles were deformed to a large extent, as shown in Figure 23c,d. Specifically, the bedding rock side has the greatest influence on the deformation of the retaining piles in the first row of the reinforcing point, while the toppling rock side has the most pronounced effect on the retaining piles in the fourth row. To solve the problems of inconsistent deformation and a sharp increase in pile body displacement at the reinforced point, an additional tie beam is considered to be added to the top of the pile top at the reinforced point to form a whole structure with the top beam, thereby restraining the deformation of the retaining pile at the reinforced point and increasing the integrity of the support structure, as shown in Figure 24a. Figure 24: Cont. It can be seen from the displacement curve of the pile body that the deformation trend of the pile body displacement curve of the middle pile and the side pile on the bedding rock side is synchronized, as shown in Figure 24b, and the maximum deformation of the row pile is the same as when no tie beam is applied. After the application of the tie beam, the four reinforcement piles on the bedding rock side and on the toppling rock side show the same trend, as shown in Figure 24c,d. The displacement of the pile top of the reinforced pile on the bedding rock side tends to be zero, which shows that the tie beam maintains the consistency of the deformation of the reinforced pile body. Therefore, the application of a tie beam is helpful for the deformation control of retaining piles on bedding rock side slopes. However, since the deformation on the toppling rock side is less than that on the bedding rock side, nonapplication of the tie beam can be considered. Displacement comparison tables of the above support schemes are shown in Table 4.  
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{ \begin{tabular}{} \end{tabular}