Influence of Width-length Ratio of Foundation Pit on Deformation of Adjacent Existing Tunnel Under Dewatering Condition
The influence of foundation pit dewatering construction on the deformation of adjacent existing tunnel has been studied by scholars,but the influence of width-length ratio of foundation pit on the maximum vertical displacement of tunnel under dewatering condition is still blank.In order to explore the influence of the width-length ratio of foundation pit on the deformation of adjacent tunnel during foundation pit dewatering,firstly,the stress and deformation rule of the adjacent tunnel is studied with the model test when the width of foundation pit and the depth of dewatering are changed.Then the influence of the width-length ratio of foundation pit is further analyzed with the numerical software.Finally,the vertical displacement of tunnel is normalized,and the influence of the width-length ratio of foundation pit on deformation of the adjacent existing tunnel under the influence of different dewatering depths is analyzed.The result shows that through the model test,it can be found that the causes obvious dewatering funnel outside the pit.With the increase of foundation pit width and depth,the amount of water increase gradually.The water level in the pit continues to decrease,and the vertical displacement and bending moment of the existing tunnel change significantly.The tunnel outside pit presents a deformation like'flat horizontal duck egg'.Through numerical analysis,it can be found that when the width-to-length ratio of foundation pit is small,the width-to-length ratio and the dewatering depth should be considered comprehensively,while when the width-to-length ratio of the foundation pit is large,the phenomenon of over-drop should be particularly avoided.In addition,through normalization,it is found that the displacement curves at each dewatering depth approximately satisfy the same function relationship.When the width-to-length ratio of foundation pit is less than 0.4,the larger the width of foundation pit,the larger the displacement of tunnel.When the width-to-length ratio of foundation pit is greater than 0.5,the vertical displacement of tunnel will not increase with the increase of foundation pit width,but the range of tunnel displacement will increase by 4 to 5 times.
tunnel engineeringdeformation of adjacent existing tunnelnumerical simulationwidth-length ratio of foundation pitfoundation pit dewatering
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