Numerical Analysis Of Aseismatic Capability Of Rigid Pile Composite Foundation With Variable Rigidity

The variable stiffness rigid pile composite foundation may the full use of foundation soil properties,the nature of the pile group, from the stress and the strain of the pile of pile and soil consider the superpositionof stiffness, the group of pile foundation bearing capacity requirements to seismic requirements, and reducethe overall structure of the settlement, reduce the investment comprehensive effect. At present thegeotechnical engineer has been paid much attention. Usually, the rigid pile composite foundation, the verticalstress change is far away from the base, the stress, deformation and the more small, the foundation for overallrigidity are smaller, and the variable stiffness the rigid pile composite foundation just meet this requirement,the stiffness in when is larger, the stiffness in when decrease. Variable stiffness in the rigid pile compositefoundation, long piles up load will be to pass deep foundation, reduce the overall structure of the settlement,so long pile soil stress is bigger, to long pile body strength requirement is relatively high, the more rigid pile,such as conerete pile, such as pipe pile, and short pile top to reduce stress concentration main stress to thelower transmission, improve the bearing capacity of the foundation and short pile can be used both flexiblepile also can use the rigid pile.Because the variable stiffness rigid pile composite foundation is the product of in recent years, therelevant his study also less, limited research generally limited in the bearing capacity and settlement direction,about the direction in seismic research has not had. By using the ANSYS finite element software, to severaldifferent types of the rigid pile composite foundation of plastic analysis based on the3d numerical analysis,the rational model size and cushions selected, to eliminate the influence of gravity load in under, consider theupper structure-the foundation-the foundation work together, the anti-seismic performance study.The variable stiffness rigid pile composite foundation and the rigid pile composite foundation,under the action of earthquake in one way, the upper structure of displacement, the pile of displacement,bending moment and shear are with the increase of earthquake intensity increase exponentially, namely with earthquake is proportional to the acceleration, the displacement, moment, shear are found in the biggestpoints of acceleration. In the same column pile, parallel to the earthquake effect on the direction of pile sidedisplacement, moment, shear are than other big pile. Variable stiffness in the rigid pile composite foundation,long piles of moment far outweigh the short pile, large diameter pile of moment far outweigh the smalldiameter pile. Changing length of the rigid pile composite foundation, pile long range in there are two mostpoint bending moment, the pile the lower half of the moment the most value far outweigh the pile of the uppervalue; The most value of shear appear in both ends of pile, including pile low shear significantly greater thanthe pile top shear. Change the pile length change than pile diameter schemes of pile shaft bending momentand shear increased, become the pile length scheme is become by pile diameter less; Change the pile lengthdisplacement, and the upper portion of the scheme of pile body position shifted corolla pile and become lesspile diameter plan; Change the pile length concrete consumption minimum scheme, the most economy; Inconclusion, changing length of rigid pile composite foundation, the seismic performance is better thandiameter of the rigid pile composite foundation..