# The Influence of Metro Tunnel Construction Parameters on the Settlement of Surrounding Buildings
## 5 Conclusions  
Based on the research results, statistically significant parameters were identified, which formed the basis of the regression equation, allowing the assessment of absolute deformations accumulated over a distance of 10 m along the planned route before reaching the planned mark of geotechnical monitoring. The characteristics listed below have statistical significance and were used to create the final equation. The most significant impact on the settlement size is made by the parameter the average face-support pressure for a 10 m section (P\({}_{\text{avg.10}}\)). Among all the parameters studied, this one, at its average value, has the greatest effect, reducing settlement by 36%. The next parameter in terms of weight contribution, the soil deformation modulus at the tunnel face (E\({}_{1}\)), can also reduce the settlement size by 28% (see Figure 3). However, the average soil excavation (V\({}_{10}\)) and the depth of tunnel burial (H) at average values may contribute to an increase in settlement by 25% and 11%, respectively. It should be noted that, in a previous study [27] where the authors investigated the impact of parameters on settlement over one monitoring cycle, the soil excavation parameter (V) was not statistically significant. It is important to highlight that in this model, there is no correlation between the parameters P\({}_{\text{avg.10}}\) and H, as was noted earlier [27]. Similar to the authors' previous study [27], within the available volume of data, there is no observed dependency of settlement on the volume of grouting solution injected into the space between the lining and soil mass (\(v_{10}\)). Additionally, it should be noted that the distance parameter (r) is not significant, whereas in the authors' previous work, this parameter was significant but had a minor impact on settlement size compared to other parameters [27]. Thus, the traditional conception of the settlement surface shape in the cross-section, described by the Gaussian curve, may be disrupted by the technological parameter of tunneling, the face-support pressure. This result can be explained as follows: a relatively small excess of the necessary face-support pressure for maintaining face stability causes a rise in the deformation mark within one cycle of geotechnical monitoring. This result contradicts other contemporary studies [1, 11, 15, 16] and can be explained by the fact that the maximum settlement of the surface occurs in the cross-section of the tunnel at some distance from the axis of the tunnel and away from the zone of active pressure impact. The difference between this work by the authors and the previous one [27] is that this time engineering-geological conditions are taken into account. The monitoring data are taken not for one cycle, but for 10 m of TBM advancement. The accumulated settlement during this time and the corresponding technological parameters are analyzed. For comparison with the presented materials, the study of our colleagues [29] is of interest. Both studies, ours and the study of our colleagues [29], involve the construction of a tunnel with similar design solutions. However, the tunnel burial depths and the engineering-geological conditions of construction differ. The study [29] considers settlement along the tunnel axis during one phase of geotechnical monitoring, whereas in our study we also analyze the accumulated settlement of the surrounding buildings, their distance from the tunnel axis, and the number of floors. One important statistical tool for assessing the adequacy of the model, R\({}^{2}\), is somewhat lower in our study, which is explained by the use of linear multiple regression. This is due to the small sample size. It may not be advisable to process data using machine learning based on a single project, as there is a high likelihood of the model being highly sensitive to new data.