# The Influence of Metro Tunnel Construction Parameters on the Settlement of Surrounding Buildings
## 2 Materials and Methods  
All the initial data, the processing results of which are presented below, were provided by LLC \"Institute \"Mosinzhproekt\" (Moscow, Russian Federation). The reliability of the data is ensured by the use of high-precision geodetic surveying and calibrated equipment for determining soil properties. In this study, a multiple regression model is employed in which the dependent variable is the total settlement of the object accumulated over a distance of 10 m along the planned route up to the point where geotechnical monitoring is conducted. The information on the plan and elevation placement of the tunnel, technological parameters with average values over 10 m, and characteristics of the soil mass act as independent variables. Samples for building regression models were obtained during the construction of the left interstation tunnel of the Rubbyovo-Arkhangelskaya metro line (RAL) using a TBM with a cutting diameter of 6.6 m, as well as during the construction of the right and left interstation tunnels of the Troitskaya metro line (TL) using a TBM with a cutting diameter of 6.28 m. The outer diameter of the left RAL tunnel is 6.3 m, and the diameter of the right and left TL tunnels is 6.0 m.  
Settlement of the monitoring object is taken as the dependent variable in this study to determine the parameters that have the greatest impact on the response. Separate models were analyzed with and without the parameter of the volume of grout injected into the space between the lining and soil mass, as the actual values are present in the dataset only for the construction of the RAL tunnel. Before constructing the main regression model, criteria were selected among the following parameters, which can be conditionally divided into five groups:  
1. Geotechnical monitoring data: * Absolute (cumulative) settlement of the monitoring object for all cycles when the TBM is at the deformation control benchmark (S), mm (1);
2. Geometric parameters: * Distance from the center of the tunnel to the deformation control benchmark (r), m (2); * Depth of the tunnel from the surface to the tunnel crown (H), m (3);
3. Weighted average characteristics of the soil mass: * Cohesion of the soil at the tunnel face (c1), kPa (4); * Internal friction angle of the soil at the tunnel face (\(\varphi_{1}\)), degrees (5); * Deformation modulus of the soil at the tunnel face (E1), kPa (6); * Cohesion of the soil above the tunnel (c2), kPa (7); * Internal friction angle of the soil above the tunnel (\(\varphi_{2}\)), degrees (8); * Deformation modulus of the soil above the tunnel (E2), kPa (9);
4. Technological parameters obtained during tunneling: * Average face-support pressure unloading vertically and along a distance of 10 m along the design route until reaching the deformation control benchmark in the plan (Pavg10), bar (10);Average ground output for installing one ring over a distance of 10 m along the design route until reaching the TBM deformation control benchmark in the plan (V\({}_{10}\)), t (11);
* Average volume of grout injection into the space between the lining and soil mass over a distance of 10 m along the design route until reaching the TBM deformation control benchmark in the plan (v\({}_{10}\)), m\({}^{3}\) (12);
* Characteristics of the surrounding buildings:
* Number of stories of the building located in the tunnel construction influence zone (L), fl. (13). When processing surface monitoring data, the number of floors is considered as 0. The face-support pressure was determined at the design stage based on the following condition:  
\[\text{P}\geq\text{P}_{\text{w}}+\text{P}_{\text{g}}, \tag{2}\]  
here P\({}_{\text{w}}\) is the magnitude of the groundwater pressure at the level where the weight load pressure is determined; and P\({}_{\text{g}}\) is the magnitude of the horizontal soil pressure at the level where the weight load pressure is determined.