| With the rapid development of Qingdao metro construction,it is necessary to further pursue greater space utilization under the condition of limited underground space,which will inevitably reduce the spacing between tunnels,and also put forward higher requirements for the development of subway construction technology.Based on the small clearance section project of the shield section of Haigang Road Station ～Chaoyangshan Road Station of Qingdao Metro Line 6,combined with FLAC3 D numerical simulation software,the influence law of surface settlement of the tunnel vault and axis of the first-run mine section and the lateral settlement law of the double-line tunnel during the excavation process of the back-running shield tunnel was analyzed,and finally based on the regression analysis method method and the introduction of the concept of mutual disturbance coefficient,the tunnel vault settlement prediction model and the double-line tunnel surface settlement prediction model were established,respectively.The following conclusions are drawn:(1)Sorting out and analyzing the measured settlement data of the construction shows that when the section(diameter)of the tunnel of the mine method section is larger and the net distance between the two tunnels is smaller,the higher the significance of the impact of the excavation of the shield tunnel on the surface settlement at the tunnel vault and axis of the mine section that is first penetrated,the closer the maximum lateral settlement difference of the surface is to the side of the tunnel of the mine method,the deeper the "V" type settlement groove of the surface settlement curve,and the construction entity analysis model is established by FLAC3 D software for comparative verification.(2)The numerical model with different net distance between the two tunnels was established to analyze the settlement law,and the results showed that the smaller the net distance between the two tunnels,the higher the significance of the impact of the rear excavation of the shield tunnel on the surface settlement at the tunnel vault and axis of the mine law section,the position with the largest lateral settlement difference on the surface showed a trend of moving from the shield tunnel side to the tunnel side of the mine law section,the deeper the "V" type settlement groove of the settlement curve,and when the net distance between the two tunnels is large enough,the surface settlement above the shield tunnel caused by the tunnel construction of the mine method section is negligible.It is much smaller than the settlement influence of the excavation behind the shield tunnel,and it is inferred that the lateral settlement curve of the surface at this time will be a "W" shape of left depth and right shallowness,that is,the settlement groove of the left line mine section tunnel is deeper than the settlement groove of the right shield tunnel.(3)The numerical model with different cross-section forms of the tunnel in the mine section was established to analyze the settlement law,and the results showed that the surface settlement at the vault and axis of the tunnel in the mine section was directly proportional to the size of the section(hole diameter).Secondly,the larger the diameter of the cave,the lower the significance of the impact of the post-excavation of the shield tunnel on the surface settlement at the tunnel vault and axis of the mine section,and the position with the largest lateral settlement difference on the surface still shows a trend of moving from the shield tunnel side to the tunnel side of the mine section,and the deeper the "V" type settlement groove of the settlement curve,but when the hole diameter continues to decrease to a sufficient hour,it can be speculated that the lateral settlement curve of the surface of the process may show from left "V" type to left deep right "W" type to left shallow right "W" type and finally even become right "V" type of change trend.(4)Based on the regression analysis method,a regression prediction model of tunnel vault settlement index function of mine method section was established,and the fitting regression analysis of some measured data was carried out in stages according to its vault settlement law,and the results showed that the predicted values of each stage regression model were in good agreement with the overall measured vault settlement values on site,which verified that the model had a good prediction effect on the vault settlement of tunnels in the mine method,which had certain guiding significance and reference.(5)By introducing the mutual disturbance coefficient μ and η,a two-line tunnel surface settlement correction prediction model in the form of segmented function is established,and the lateral settlement of the surface under the actual working conditions is predicted and compared,and the results show that the model has a good prediction effect(error <2mm)on the lateral settlement of the surface under the actual working conditions,which can provide certain reference and reference for the prediction of surface settlement of similar projects in the future. |
PDF Full Text Request