Study On A Horizontal Force And Eccentric Loads And The Rigid Pile Composite Foundation With Variable Stiffness Adjustment

With the rapid development of national economy, as a pillar industry in the national economy construction industry developed such as bamboo shoots after a spring rain like. It is because of China’s large population, resource consumption increased, people’s housing problems in the ranks of the social problems that can not be ignored. However, in order to solve this problem, the only effective way is to utilize the space environment, so a large number of high-rise buildings emerge as the times require.Although the development of the high-rise building more rapidly, but the foundation design of high-rise building is a difficult problem, especially in the poor soil areas, coupled with increasing number of layers, the upper load gradually increased, settlement will cause the foundation, thus increasing the difficulty of design foundation. Especially in today’s geological disasters occur frequently and high-rise buildings is wind loads, more increased the difficulty of foundation design.To solve the above problems, the majority of high-rise building foundation is used in composite foundation, however, leveling composite foundation for overall differences of high-rise building settlement can be reduced, which is conducive to the overall coordination structure. This article introduces the composite foundation technology development history and composite foundation leveling at home and abroad, and then introduces the principle of composite foundation and theoretical basis of flat, finally according to the composite foundation with variable rigidity in the domestic and foreign research situation, this article uses the finite element method to optimize the composite the foundation and the horizontal force and eccentric load character analysis.In this paper, based on the numerical simulation analysis, a total of18calculation scheme is established, based on the rigid pile composite foundation with the same conditions of rigid pile total materials under loads transformation group pile length raft foundation under vertical uniform transformation group, pile length of several adjustable square case comparison, a flat scheme optimum; force calculation of equivalent and then choose the optimal scheme for leveling the horizontal force and eccentric loads, and then selects the leveling before (such as stiffness of pile) stress analysis of horizontal force calculation scheme and eccentric loads; finally comparative analysis of the raft leveling before and after adjusting the difference of raft settlement and change of the bending moment, axial force and bending moment of pile group, and then draw the composite foundation leveling before and after adjusting the force changes of the raft and pile; at the same time, the best adjustment scheme for computing and analysis of raft thickness changes, cushion, cushion modulus of elasticity layer thickness, soil modulus, pile end changes between pile and soil modulus, pile stiffness change on the rigid pile composite foundation with variable stiffness leveling effect, draws the following conclusion:(1) maintain the total material pile group under the same conditions, the several methods of changing pile length adjustment basis, with a strong and weak, which increases the internal length of pile can effectively play the role of leveling base.(2) the raft leveling before and after adjusting the vertical uniform bending loads in the raft Center showed the highest value, no horizontal force and eccentric loads, leveling leveling than the moment before the raft was reduced in the moment, in the horizontal and vertical eccentric loads under the raft in the raft eccentric end fairly and raft Center value, after adjusting the adjustable additional bending moment is produced before the eccentric load in pile length will increase the local mutation.(3) based distributed under the vertical load, a leveling of smaller and the moment value of differential settlement of raft, more reasonable stress, the stress characteristics of pile groups in leveling leveling is more uniform than before; in the horizontal force and eccentric loads, foundation leveling is adjustable even before the additional bending moment at pile length mutations will be partially increase, differential settlement increased slightly.(4) between the thickness of the raft, cushion modulus, cushion thickness, pile end soil modulus, pile and soil modulus, pile rigidity of composite foundation factors, influence of raft thickness difference settlement of composite foundation, raft bending moment, axial force of pile body, pile the biggest bending moment.