Study On Uplift Bearing Capacity Of Belled Short Pile In Clay-silt Foundation

Belled short pile are widely used in transmission lines because of their outstanding uplift bearing capacity,obvious economic benefits,and low environmental impact.However,when the belled short pile foundation is buried in different soil layers,its uplift bearing capacity is significantly different from that in a single soil layer.In order to study the bearing capacity of the belled short pile in clay-silt foundation and the effect of soil layer changes on the bearing capacity,based on the project of"Optimizing Technology and Application of Bottom Expansion Design for Digging Pile Foundation on Cohesive Soil",this paper carried out the uplift bearing capacity of belled short pile in clay-silt foundation by field test and numerical simulation the study.The main work and results of the thesis are as follows:（1）The uplift load-displacement curve of the belled short pile in the clay-silt foundation is"gradually variable";the Terzaghi and Peck method can be used to determine the ultimate bearing capacity of the uplift test foundation of the belled short pile in the clay-silt foundation.The corresponding displacement sT&P=25.4 mm can basically meet the basic displacement requirements.（2）By comprehensively analyzing the changes of the surface displacement,the displacement of the top of the foundation during the loading of the real test,the uplift failure mode of the belled short pile in the clay-silt foundation is the overall failure.（3）The FLAC^3D software was used to establish the numerical calculation model of uplifted belled short pile,the influence of different soil layers on the uplifted load-bearing performance of the belled short pile was simulated and analyzed.The numerical simulation results show that the uplifted load-displacement curve of the belled short pile in the clay-silt foundation is"gradually variable";After the soil layer changes,the failure mode is still the overall failure.During the uplifting of the belled short pile,the earliest soil damage area is the pile top area and the enlarged head top area;When the size and material of the belled short pile body are unchanged,the thickness of the clay layer of the foundation increases,and the later the plastic zone penetrates.（4）Several theoretical calculation methods were analyzed,and a suitable method was selected to calculate the ultimate bearing capacity of the belled short pile in the clay-silt foundation.