Abstract:

In the paper, the design of the endsuspended piles of the foundation pit of May Fourth Square Station of Line 3 of Qingdao Metro, which is located in soilrock combined strata, is studied. The correlation between the deformation and internal forces of the support system of the foundation pit with endsuspended piles located in soilrock combined strata and the rocksocketed depth and rock shoulder width of the endsuspended piles is analyzed by means of numerical simulation. Furthermore, the displacement and bending moment of the endsuspended piles with vertical load and without vertical load are also studied. Conclusions drawn are as follows: 1) With the increase of the cutting depth and the installation of the rock bolts, the prestressed footlocking rock bolts have obvious effect in the control of the horizontal displacement of the ends of the endsuspended piles; 2) With the increase of the rocksocketed depth and rock shoulder width, the maximum horizontal displacement of the endsuspended piles reduces; It is proper that the rocksocketed depth should be taken as 2.0 m and the rock shoulder width should be taken as 1.5 m; 3) Because the ends of the piles are socketed into the intermediatelyweathered granite, the displacement of the pile top is not controlled by the vertical load, however, it increases obviously as the cutting depth increases; the bending moment of the pile increases slightly, with very small increment. 

Key words: soilrock combined strata, cut and cover, Metro station, endsuspended pile, rocksocketed depth, rockshoulder width