The Horizontal Bearing Capacity Of High Strength Composite Pile In Bi-directional Cement Mixing

High Strength Composite Pile in Bi-directional Cement Mixing is a new composite pile proposed with the more mature construction technology.The difference between this composite pile and the traditional composite pile is the improvement of the construction technology of cement mixing pile.At present,the research on the calculation theory of the horizontal bearing capacity of this new composite pile is still not mature.With the two actual projects as basis,theoretical analysis and finite element simulations,the horizontal bearing capacity of the new composite pile is studied.The main research work and results are as follows:(1)The theory of horizontal bearing calculation of pile foundations domestic and international is studied.Combining the horizontal force characteristics of the strength composite pile in bi-directional cement mixing,the new calculation formula of m-method suitable for this type of composite piles is proposed.Combining the horizontal loading test of the strength composite pile in bi-directional cement mixing in the No.3 project of Suzhou Moon Bay and the No.3 project of Nantong Zhongnan Century Flower City,the test records the horizontal displacement of the top of the pile under various loads.Then the horizontal limited load values,the horizontal critical load values and the horizontal bearing capacity eigenvalues of these piles are determined by the graphs drawn by the data according to the specifications.The values provide a reference for the following theoretical calculations and finite element simulations.(2)When the horizontal bearing capacity of the strength composite pile in bi-directional cement mixing is calculated by m method,the static elastic modulus of the pile can be calculated by substituting the wave speed obtained by the low-strain test into an empirical formula.When calculating m value from data of the horizontal loading test,the horizontal critical load shall be taken as the design value of the horizontal bearing capacity of the composite pile.It is found that the m value calculated above is close to the value of the m value of the corresponding cement mixing pile in the Technical Specification for Construction Pile Foundation(JGJ94-2008).According to the process of the calculation above,it should use the width of the cement mixing pile to calculate the horizontal bearing capacity of the composite pile.Combining the p-y curve method in soft clay put forward by Matlock,the new p-y curve empirical formula that is suitable for the strength composite pile in bi-directional cement mixing in soft soil is proposed by fitting at least squares principle according to the experimental data.(3)ANSYS finite element software is used to numerically calculate the horizontal bearing capacity of the strength composite pile in bi-directional cement mixing.Comparing with the results of the horizontal loading test,the finite element model is feasible.The software is used to explore the effect of different diameters of the cement mixing pile on the horizontal bearing capacity of composite piles.It is concluded that the composite piles can greatly improve the horizontal bearing capacity of pile foundations when compared with the concrete pipe piles,But refering to the numerical simulation results of the diameter of the pile which is 800 mm and 1200 mm,it can be inferred that the effect of increasing the diameter of the cement mixing pile to improve the horizontal bearing capacity of the composite pile will be not great when the diameter of the cement mixing pile reaches a certain critical value.