## 4 Conclusions  
In this study, the microtremor exploration method was conducted to carry out advanced geological detection that cannot be determined by borehole detection. The results were compared with those of borehole sampling. The shield construction parameters were guided and adjusted according to different geological conditions, the surface deformation perpendicular to the tunnel axis was monitored, and the earth pressure outside the segment was monitored with an automatic earth pressure monitoring system. The following conclusions can be drawn:  
1. The geological results obtained from microtremor exploration can make up for the shortcomings of traditional borehole geological exploration. The geological distribution obtained by microtremor exploration is consistent with the results of four borehole samples, which can clarify the effectiveness and reliability of this detection  
Figure 9: Variation of earth pressure outside the segment with time: (**a**) L2; (**b**) L1; (**c**) B3; (**d**) B5; (**e**) B6; (**f**) B7. method. This method can predict the possible local geological mutation in the ground in front of the tunnel and adjust the construction parameters in advance to ensure the safety of shield construction;
2. Through the dynamic adjustment of grouting parameters, the surface deformation is shown as overall settlement, and the curve law conforms to the settlement distribution of the Peck formula. The vertical displacement of soil mass mainly goes through five stages: small deformation far from the section, extrusion uplift close to the section, reciprocating uplift deformation through the section, settlement after the shield tail is pulled out, and consolidation settlement deformation law far away from the section. The surface subsidence on the eccentric load's side is more obvious. The volume of ground settlement in the shield tail stripping stage has increased significantly, and the grouting behind the wall should be given more attention in actual projects;
3. When the earth pressure monitoring section is outside the shield tail brush of the shield machine, there is no apparent pressure change. When the shield machine is advanced, the earth pressure outside the segment increases dramatically when it enters the shield tail brush range. The maximum pressure outside the tunnel segment appears on the lower side of the monitoring section, at approximately 0.41 MPa. When it comes out of the shield tail brush, it increases with the increase of grouting pressure and tends to be stable in the following days. The methods and results might be of interest to engineers, tunnel researchers, and industrial geologists who focus on advanced engineering geological exploration and shield tunnel construction. Microtrenor exploration only detects the geological conditions in front of the tunnel, ignoring the identification and analysis of different underground obstacles, including pile foundations, diaphragm walls, existing tunnels, faults, karst, boulders, and other unfavorable geological bodies. Only the data comparison between the stratum and a small number of investigation holes is considered, and the fretting detection of a large number of investigation holes should be carried out subsequently to form a database and to comprehensively and deeply study the fretting detection method. In addition, the monitoring section is located on the main road. This study did not reach the rock cross stratum section for monitoring due to safety considerations. In the future, we will look for more suitable engineering cases for the in situ test of soil deformation and further explore the law of soil deformation caused by shield tunneling in the composite stratum. Conceptualization, methodology, supervision, Z.W., X.L. and Y.X. ; data curation, formal analysis, J.S. and R.W. ; investigation, original draft preparation, formal analysis, J.S., R.W. and Z.Y. ; writing--review and editing, Z.W. and J.S. ; project administration, X.L. and Y.X. All authors have read and agreed to the published version of the manuscript.