Design And Numerical Simulation Study On Super Deep Foundation Pit With Pile-Anchor Support

Underground space utilized getting more and more as the construction of urbanization developed rapidly in China.And the foundation pit engineering played an important role,especially the super deep foundation pit of more than 23m.It was confronted with the challenges such as the stricture space of city and surrounding underground pipeline.The imperial art center of super deep foundation pit engineering in Beijing as the support of this paper.According to the engineering geological conditions and experience in this region this super deep foundation pit was designed with pile-anchor retaining.Modeled and analysed the procedure of excavation and the supporting structure of super deep foundation pit employing FLAC 3D software.This foundation pit is located in the crowed places with couples of pipelines and buildings.It would had an excavation depth of 29.20m.All of these has strict requirements on the deformation of foundation pit and the pile-anchor retaining scheme was taken.Also calculated the pile-anchor retaining scheme of this super deep foundation pit,the results show that the checking calculation can meet the standard requirements.The pile-anchor retaining scheme based on FLAC 3D,modeled the super deep foundation pit excavation and researched the rule of changes about the ground settlement of surrounding,the displacement of slop protection pile,the upwards deformation at the bottom of foundation pit and the most biggest axial stress and so on.The following results were got.?The biggest soil horizontal displacement of foundation pit is the place of sandy-pebble layer in Beijing.?The mainly places of ground settlement of surrounding is the soil mass in 16m at the back of slope protection pile.And the maximum ground settlement value in about 6m to 8m from slope protection pile.?The change rate of horizontal displacement of pile block turn from small to large and tending to stable at last.In addition,the horizontal displacement of pile block have a process turn to inside of foundation pit then springback after each excavation.?The displacement of pile turn big as the depth of excavation turn big and the biggest displacement of pile taking place at the depth of 20m.The displacement value tending to zero at the maximum excavation depth.?The maximum axis stress by anchor endured appeared at the fourth row of anchor.And the maximum axis stress appeared at the anchorage section telos near the free section every anchor.The axis stress get smaller and smaller down the anchorage section.And the axis stress tending to zero at the root of anchorage section.The field monitoring proved the numerical modeling working effectiveness in contrast with the calculated value and measured value about the ground settlement of surrounding,the displacement of slop protection pile,the upwards deformation at the bottom of foundation pit.It conclude that this paper's research achievement have the look-ahead forecast.Its also provided important reference for the similar and associated works.