## 6 Conclusions  
This study took the shield tunneling construction of the round gravel stratum in the access section of Hangzhou Metro Line 3 as the background and relied on field monitoring data of the test section. In the monitoring area, the variation law between the tunneling parameters such as chamber earth pressure, thrust force, the torque of the cutter, grouting volume and grouting pressure and the deformation of the surface section, vertical displace  
Figure 21: Figure of abnormal vertical displacement of stratum on the south line.  
ment, and horizontal displacement of the stratum during the shield tunneling process were analyzed. The main conclusions are summarized as follows:  
1. When the EPB shield passes through the round gravel stratum, the chamber earth pressure, thrust force, torque of the cutter, grouting pressure, and grouting volume are all positively correlated with the surface. Before the shield arrives at the section, the influence of chamber earth pressure, thrust force, and torque of the cutter on the surface deformation are mainly affected by the change in the stratum soil pressure in the tunneling stage, and the chamber earth pressure is the tunneling parameter that affects the surface deformation the most. In the stage of the shield tail passing section, the grouting volume and grouting pressure on the surface deformation are mainly affected by the change in the void ratio of the stratum, and the grouting volume is the tunneling parameter that has the greatest influence on the surface deformation.
2. During the process of the EPB shield passing through the round gravel stratum, the deformation curve of the surface corresponds to the Gauss curve, and the curve law conforms to the settlement form of the Peck formula. The heave value of the southern line reaches the maximum during the crossing stage, and the northern line reaches the maximum when it approaches the monitoring surface.
3. The stratum around the southern line was heated before the shield arriving section, fluctuated during the crossing stage, decreased after the shield tail pass section, and finally stabilized. The closer it is to the tunnel, the greater the degree of disturbance and the greater the change in the vertical displacement of the ground surface. The stratum displacement of the north line is weak before the shield arriving section reaches the heave degree, and it is in a settlement state during the crossing stage and after the shield tail passing section. Combining the three aspects of soil layer thickness, soil compressive modulus, earth stress release, and grouting pressure offset, the problem that the settlement value at the depth of 6 m is greater than that at the depth of 8 m and 10 m is explained.
4. The horizontal displacement of the soil increases along with the depth fluctuation and the maximum value is observed at a depth of 10 m. In the tunneling stage, the minimum value occurs when the shield does not reach the monitoring section, and the maximum value is reached when the shield tail passes the section. The closer to the tunnel axis, the greater the horizontal displacement along with the depth.  
Conceptualization, methodology, supervision, Z.W., J.S. and S.X.; data curation, formal analysis, S.W., W.F. and P.W.; investigation, original draft preparation, formal analysis, W.F. and S.W.; writing--review and editing, W.F. and Z.Y.; project administration, Z.Y. and J.S. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.