| The stability of support structure of the deep foundation pit is an important guarantee for the safety of the deep foundation pit.However,while ensuring the safety of the deep foundation pit project,it is also necessary to take into account its economics.Therefore,higher and stricter requirements are imposed on the supporting structure of deep foundation pits.Due to the strong complexity and locality of the rock and soil,the support structure of deep foundation pits has always been the focus and difficult part of research on engineering problems of foundation pits.Based on t the foundation pit project of the 14# pier arch seat of Qianwei Minjiang Bridge,this paper studies on a new type of foundation pit supporting structure,such as arched bite pile supporting structure.By using Midas GTS NX finite element software,an analysis model considering the seepage-stress coupling is established,which can simulate the foundation pit precipitation excavation process.The calculation results are compared with the monitoring data of the construction site of the foundation pit,and the deformation law of the supporting structure during the excavation of the foundation pit is analyzed in detail.Then on the basis of this model,the influence of the design parameters of the arched occluded pile supporting structure on the mechanical deformation and the stability of the foundation pit was analyzed to provide a basis for the optimal design of the arched occluded pile supporting structure.The main results of this study are as follows:(1)In the process of dewatering excavation of the foundation pit,the deformation of the supporting structure of the arched occlusal piles is generally small.The maximum horizontal displacement occurs at the arch crown of the supporting structure,and the horizontal displacement on the supporting structure is distributed from arch crown to arch foot from large to small.The supporting pile at the arch foot of the arched occluded pile supporting structure has complicated stress,and there are multiple anti-bending points of the bending moment.Above the excavation surface,the maximum bending moment of the supporting pile at the arch foot is generated at a depth of-8.5m.Below the excavation surface,the position where the maximum bending moment occurs continues to move downwards,and finally stabilizes at a depth of-19.5m.(2)The range of 20 m around the foundation pit is the main impact area of surface soil settlement caused by precipitation excavation.The surface settlement around the foundation pit is distributed in the shape of a "scoop".The maximum surface settlement occurs at a certain distance from the foundation pit,about The occlusion pile support structure is about 5.6m behind the crown of the arch.During the foundation excavation,the surrounding surface settlement is generally small,which shows that the arch occlusion pile support structure can effectively limit the soil settlement deformation.(3)Changing the stiffness of the connecting beam at the top of the pile and the insertion ratio of the pile body of the supporting pile at the arch foot has little effect on the deformation of the arched occluded pile supporting structure.The surface settlement around the foundation pit and the uplift of the bottom of the pit.So under the premise that the supporting structure can meet the strength requirements,the connecting beam at the top of the pile can meet the structural requirements,and the insertion ratio of the pile body should not be set too large.(4)The changes in the amount of bite,the diameter of the supporting pile at the arch foot,and the ratio of the vector to the span have a significant effect on the deformation and stability of the arched bite pile supporting structure and the stability of the foundation pit.The optimization design should focus on the parameters such as the amount of bite,the diameter of the supporting pile at the arch foot and the ratio of the vector to the span.For different design requirements,reasonable optimization measures can be taken. |
PDF Full Text Request