A Method To Predict The Settlement Of Pile Foundation Based On The Results Of Vertical Static Load Test Of Single Pile

Pile foundation,as one of the common foundation forms of high-rise buildings,large bridges,etc,has been widely used.The settlement of pile foundation plays an important role in the safety and serviceability of the structure.Therefore,accurate prediction of the settlement is an important work in the design of pile foundation.Though many methods to compute pile foundation settlement have been developed,the accuracy of computed results is not satisfied in many cases.On the other hand,the vertical static load test is one of widely used method for single pile,whose testing results imply the mechnical properties of pile,soils and the interaction between them,so it becomes a logical idea to predict the settlement of pile foundation bases on the results of the test.Based on this idea,the following research work has been carried out in this thesis:(1)To overcome the disadvantages of the existing methods for predicting settlement of pile foundation based on the results of vertical static load test on single pile,a new method based on elastic theory is developed,in which the compatibility condition of settlement between the pile foundation and soil mass can be satisfied and the deformation modulus of soil is determined based on the results of vertical static load test on single pile.(2)Some problems in the elastic method such as the accuracy of cohesive model,the discretization of pile in the computation was discussed and corresponding suggestions were given based on the computed results of FEM.(3)The settlements of 75 groups of pile group with different layouts,numbers,spacings and lengths were calculated using ABAQUS finite element software.The results show that the "reinforcement" effect of the group piles will reduce the settlement of the pile in the group and the interaction coefficient of the two piles,so the settlement of the interaction coefficient method in which the reinforcement effect is ignored may have a large error.(4)Based on the solution of elastic theory method of single pile,the equilibrium conditions of pile cap and compatibility of settlements between the piles and the cap,the equations to solve the settlement were established.In addition,the modulus of elacticity can be determined based on the load-settlement curve obtained from the vertical static load test on single pile,which can well reflect the non-linear properties of soils.(5)The presented method was programmed using Matlab software and was applied to compute the settlement and axial forces of two actual pile foundations.The computed settlements agree well with the measured settlements,which verified the feasibility and reasonableness of the presented method.