Calculation And Analysis Of The Pile's Settlement Under Pile-soil Softening

When small loads exert to pile' s top, the top concrete is compressed and produce a displacement, an upper pile-side resistance can develop, Along with the increase of the loads, displacement gradual creation from top to bottom, pile-side resistance also exert from top to bottom , the pile-port resistance appear at this time immediately, this process will finish until the pile break .Thus it can be seen: pile-side resistance doesn' t exert in-phase with pile-port resistance , at the same time , with the increase of pile-top displacement the carrying-capacity of pile is gradually elevating .But in nature, But in nature, because of some influencing factors such as the big diameter long-pile grows a great pile-body compress and mud skin and destruction of soil's structure, pile-soil usually appear slippage, this will leads carrying-capacity of pile to decrease with the increase of pile-top displacement, this paper will study the single-pile's settlement when the slippage produce in pile-soil.Firstly, according to the actual engineering, I put forward the research background and some engineering examples, I define the slippage based on this, as to it' s produce, endanger and the processing did the summary. For computing the single-pile's settlement, this paper summarizes the past' s researching result to this topic, relatively choosing to use the load-trasfer method as the paper' s computing method.Secondly, analyzes the soil' s basic character and model based on the definition of the slippage. With tri-linear softening model to pile-soil and bilinear hardening model to pile-end soil, a set of analytical equations for variation of the axial force along depth and the pile-top load-settlement curve are established, for studying the pile-soil's slippage, the paper give some influencing factors.Thirdly, by using the great FEM programme , this paper analyses the characteristics of pile' s settlement, the soil model adopts the Drucker-Prager model, the pileself adopts the line-elastic model, pile-soil contact adopts coulomb rub form, contacting elements choose the TARGE169 and the C0NTAC172s of procedure. The pile and the soil adopt four nodes unit of PLANE42, and consider the self-gravity beginning stress field, set up the model on these grounds, analyze the factors such as the pile' s length, the E of soil etc. to influence the pile's settlement.Finally, analyze and sum up a actual engineering, get some calculation parameters, compute at certain loads can educe corresponding pile' s settlement and get a curve of Q- S, with this and the curve of Q-S that experiment to gain physically compare, result certificate match good.