Study on Influence of Pit Toe Width of Water-rich Stratum on Deformation of Support Structure of Pit-in-pit
With the continuous development of underground space,pits in pits are more and more common in engineering,but the research on pits in pits is not comprehensive at present.Based on the research background of the pit in Aixihu lake tunnel in Nanchang,Midas GTS/NX finite element software was used to study the influence of pit toe width on the deformation rule of foundation pit retaining structure in water-rich stratum.The correctness of the model and the necessity of considering the seepage condition were proved by comparing the simulation results with the measured ones.The results showed that increasing the width of pit toe could effectively reduce the horizontal displacement of the outer pit envelope,and the position of the maximum horizontal displacement would gradually increase.The increase of pit toe width had a significant effect on reducing the horizontal displacement of pile rows in the pit.Pit toe width increased from 2 m to 12 m,and the maximum horizontal displacement decreases by 76%.With the increase of pit toe width,the surface settlement would gradually decrease.Under the conditions of the project site,pit toe width should be increased as much as possible to reduce the deformation of the inner and outer pit envelope.