Simulation Study of Seepage by Group Wells for a Loess Aquifer Tunnel along Yinchuan-Xi'an High-speed Railway
Research purposes:This study addresses the issues of seepage water encountered during the construction of the Shangge Village Tunnel in the Yinchuan-Xi'an High-speed Railway,which traverses through the Dongzhi Loess Aquifer.Influenced by groundwater seepage,the phenomenon has led to the increase of water content in the tunnel's loess walls and deterioration in the stability of surrounding rocks.To resolve the construction challenges posed by the highly water-bearing loess in the Shangge Village Tunnel,this study first analyzed the distribution characteristics of the loess aquifer in the tunnel.Secondly,it introduced surface precipitation as a construction assistance measure and evaluated its effectiveness.Finally,utilizing MIDAS/GTS,the study established a tunnel engineering group well dewatering model to simulate seepage under various flow rates and permeability coefficients during tunnel excavation.Research conclusions:(1)Through the implementation of surface precipitation to drain groundwater within the loess aquifer,particularly in the long sections of the Shangge Village Tunnel,stability of the loess walls within the tunnel cavity was enhanced,ensuring both safety and progress in tunnel construction.(2)Numerical simulation results for different single-well flow rates(80 m³/d,90 m³/d,100 m³/d)in the group wells indicate that groundwater levels reached the design requirements within a short period,validating the effectiveness of the dewatering design parameters.(3)This study can provide a basis for the construction and design of water-rich tunnels in low-permeability rock masses like loess.
Yinchuan-Xi'an High-Speed Railwayloess tunnelaquifergroup well dewateringseepage simulation
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