Research on Groundwater Control Technology of Open-Cut Tunnel Foundation Pit in Water-Rich Sandy Soil Area
[Purposes]In order to study the influence of foundation pit dewatering on open-cut tunnel con-struction in complex environment and ensure the safety and reliability of construction process,the con-struction scheme is analyzed by analyzing geological conditions,field dewatering test and numerical simulation.[Methods]A two-dimensional model suitable for the airport tunnel project of Jinan Connec-tion Line of Tianjin-Weifang High-speed Railway was established by using ABAQUS software on the ba-sis of the on-site dewatering test data.The dewatering process of tunnel foundation pit was simulated,and the effect of different dewatering measures under the tunnel and the soil deformation outside the pit were analyzed.By comparing the simulation results with the field test results,it is proved that the estab-lished model is suitable for the dewatering design of airport tunnel foundation pit.[Findings]① In the sandy soil formation,the use of 3～7 mm filter material in the dewatering well will cause the sediment content of the dewatering well to be too large,and the situation will be improved after the coarse sand with smaller particle size is used.②The impervious curtain has a certain inhibition effect on the lateral deformation of the soil outside the impervious curtain,and the closer the impervious curtain is,the more obvious the inhibition effect is.When the hanging suspended impervious curtain is used alone,the maxi-mum lateral deformation of soil layer occurs in the soil layer below the impervious curtain is 1.63 mm.When the suspended impervious curtain+SMW construction method,the maximum lateral deformation outside the pit still occurs at the bottom of impervious curtain,and the maximum lateral deformation is 1.87 mm.③the diaphragm wall has an inhibitory effect on soil deformation,but its length has a limited range of inhibition on soil deformation outside the pit.The maximum lateral deformation of the soil out-side the diaphragm wall occurs at 1.45 times the excavation depth,and the maximum lateral deformation is 2.4 mm.[Conclusions]Suspended impervious curtain,suspended impervious curtain+SMW construc-tion pile and underground diaphragm wall all have inhibition effect on soil deformation,and the degree of influence is inconsistent.
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