Optimization of Combined Support Systems for Existing Subway Ancillary Structures Affected by Adjacent Excavation
This paper proposes a combined support system comprising retaining piles,tensioned anchor rods,and inclined anchor cables with grouting to solve the problems associated with constructing supporting structures for deep excavations near obstacles on one side.The study utilized Midas software for modeling,and single-factor optimization analysis schemes were designed considering four aspects:spacing and diameter of tensioned anchor rods and number and length of segments for inclined tensioned anchor cables.The rationality of this scheme was validated using engineering examples.The results showed a match between the simulated trends of the horizontal and vertical displacements of the slope-protection pile tops and the monitoring results.The vertical displacement exhibited a parabolic trend,and the horizontal displacement exhibited an arched shape.The maximum horizontal displacement of the pile tops decreased as the spacing of the tensioned anchor rods decreased and increased as their diameters and the number and length of segments of inclined tensioned anchor cables decreased.During construction,the deformation of subway ancillary structures was well-controlled and significantly less than that of the adjacent deep excavation.The top settlement showed a fluctuating upward trend,whereas the deep horizontal displacement had a middle-high and end-low pattern at different excavation stages.As the excavation depth increased,the subway structures'maximum horizontal deformation shifted downward along the shaft wall.
urban rail transitcombined support systemsubway ancillary structuressupport optimizationnumerical calculation
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