The safety risks associated with ultra deep foundation pit constructions in water-rich areas under complex geological conditions are high.Effective seepage control measures are critical to ensuring the safety of foundation pits during construction.U-sing the ultra-deep foundation pit of the Luotian Reservoir to Tiegang Reservoir Tunnel Project in Shenzhen City as a case study,a three-dimensional finite element model was developed to assess the seepage behavior in the foundation pit.The model evalua-ted the influence of factors such as fault fracture zones and the integrity of the ground walls during excavation,as well as the over-all seepage stability of the foundation pit.The results indicated that:①Without a ground wall,the seepage flow during foundation pit excavation could reach 4 018 m3/d,significantly affecting the surrounding groundwater,with an impact radius of over 100 m.②The use of high-pressure sprayed ground walls showed effective seepage control,with no stability issues during stepwise exca-vation.Once the bottom plate was poured,leakage was reduced to less than 10 m3/d.Additionally,the ground wall helped isolate surrounding groundwater,preventing the formation of a groundwater depression cone and maintaining a stable groundwater level.③If the ground wall's integrity was weakened of increasing the permeability by an order of magnitude,leakage may multiplied more than double.④Fault texture also influenced foundation pit leakage,if permeability in fault fillers increases from 10-4 cm/s to 10-3～10-2 cm/s the leakage would rise by 12 to 80 times.For ultra deep vertical shafts,especially in areas with complex geolog-ical conditions and passing faults,high attention should be paid to the construction quality of the ground wall of foundation pits,ensuring the anti-seepage effect of the wall joints to meet the safety requirements of vertical shaft seepage.These findings can provide a valuable reference for the design and construction of seepage control in ultra-deep foundation pits.
关键词
超深竖井/渗流/断层破碎带/地连墙/罗田水库—铁岗水库
Key words
ultra deep foundation pit/seepage/fault fracure zone/ground wall/Luotian Reservoir-Tiegang Reservoir
维普
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