Numerical Analysis On Design Of Dualistic Foundation Pit With "End-suspended Pile" In Qingdao

With the rapid development of urban construction, high-rise building sprung up there in short order, at the same time, urban living space is limited, when,people start to develop underground space and increase the depth of excavation. The changes of the support program in excavation are large, and with the changes of manner, depth and engineering geological conditions in excavation,they will alter, so, in order to adapt to the development of foundation pit engineering, there has been a lot of special type of deep foundation pit supporting structures. In recent years, because that the demand on environmental effect in excavation become more and more strict, the study on these special deep foundation pit supporting structures will be more important.In this paper, "end-suspended pile" was select to be studied,it is a special foundation pit supporting structure in Qingdao. The paper combined Theoretical analysis with Qingdao Railway Station retaining Projectto make researches on design, calculation and stability of "end-suspended pile" in order to give beterr advice about design and construction of these projects. The key of the Excavation is that how to optimize the design and calculation, In view of the characteristics of these engineering ,this paper made an analysison the Influencing factors related to design and calculation separately.Firstly, it is the first step to study the structure of the soil, the "end-suspended pile" was derived from such a dual structure of the soil, that is, the upper layers are soil,thelower is bedrock. In this paper, the research select two different method to calculate the earth pressure of such two soil layers,and made the layered soil pressure became one equivalent layer in order to Calculate expediently later.The value Calculated with the two different equivalent method was very closed.Secondly,the main object studied in this part was the method of the calculation , the article applied two different calculation methods to the calculation of the two phases in excavation . When the upper soil excavation, the traditional methods of design and calculation were used, such as elastic-resistance method, the equivalent beam method and one-half share method. the calculation results was closed and fine; When lower, the design method of equivalent earth pressure was aplied,thatis, set a anchor axial force on the foot of the pile to make up the lake of the passive resistance. In this paper, the method when cauculate the equivalent value of axial force with was analyzed,the researchu used two experiential methods and traditional methods to cauculate the axial force,the value was almost the same.Finally, this paper verifid feasibility of the design and calculation methods brought in the research and analyzed the with finite element method.In the article,the research based on the the design parameters calculated above to set up finite element model, and to do deal with the previous calculation. According to the excavation works carried out, simulation of the actual excavation was actualized,then,through the results , deformation and forces of the soil and structures could be analyzed and contrasted with value monitored.At the same time, through analyzing the safety coefficient of all steps calculated by using strength reduction method,the method of Calculation was reasonable,could be applied to the design and construction of the engineering. As a result of study,the main factors were simulated in order to get the disciplinarian of all factors,then,to make the design more eximious.