## 5 Conclusions  
Freezing method construction around high-rise buildings is paired with great safety risks and there is no engineering experience to refer to at present. This paper successfully carried out the freezing method construction around the main shaft tower of Chensilou Coal Mine by taking protection measures, such as symmetrical drilling, local freezing and hot water circulation. The following conclusions can be drawn.  
(1) The change patterns of the settlement and inclination of the shaft tower foundation were obtained by measuring its elevation continuously during the DHS process. The measurement results showed that the shaft tower foundation experienced four stages, namely, slow settlement, slight heaving, rapid settlement and stabilization through the DHS process. The thaw settlement amount is much greater than the frost-heaving amount, and the tower foundation deformation in the thaw settlement stage deserves engineers' attention.  
(2) During the DHS process, the shaft tower foundation first inclined northeastward at the drilling stage, and then recovered towards southwest due to frost heaving, and the shaft tower tilted further eastward at the thaw settlement stage. Benefiting from the abovementioned protective measures, the stability of the shaft tower foundation was ensured with the maximum inclination value (\(-0.406\) mm/m) well below the allowable value (\(2.5\) mm/m).  
(3) According to the on-site conditions, a numerical model of the shaft tower was established. The model results showed that the peak tensile stress on the upper surface of the main beams existed at the joint between the pilaster and the main beams of the shaft tower. When the tower tilted to one side, the peak value of tensile stress appeared on the other side of the main beam.  
(4) The fitting equation between the peak tensile stress on the upper surface of the main beams and the inclination of the shaft tower was obtained. If the safety of the shaft tower was to be ensured, the inclination values of J1-J2, J3-J4, J1-J3 and J2-J4 could not exceed \(0.788\), \(0.520\), \(0.835\), and \(0.723\) mm/m, respectively. In similar freezing method construction, a numerical calculation model should be established in advance according to the actual conditions, and the building inclination must be controlled according to the limit value that is obtained by the numerical calculation.  
Methodology, W.Q.; field investigation, W.Z. and H.Z.; laboratory test, J.G. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (Grant 52174212) and the Fundamental Research Funds for the Central Universities (Grant 2020 ZDPYMS17).  
Not applicable.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Monitoring Line for Inclination** & **Fitting Equation** & **Correlation Coefficient R\({}^{2}\)** \\ \hline J1-J2 & \(\sigma 1=1.6124\)T + \(0.5086\) & \(0.9792\) \\ J3-J4 & \(\sigma 2=2.4831\)T + \(0.4907\) & \(0.9736\) \\ J1-J3 & \(\sigma 3=1.3936\)T + \(0.6156\) & \(0.9173\) \\ J2-J4 & \(\sigma 4=1.3883\)T + \(0.7776\) & \(0.9126\) \\ \hline \hline \end{tabular} Note: T is the inclination of the concrete main beam, mm/m.  
\end{table}
Table 4: Fitting equation and correlation coefficient between the peak tensile stress on the upper surface of the main beams and the inclination of the shaft tower foundation.