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针对刚性筏板下群桩基础优化设计问题进行分析,通过改变桩长分布来调整各桩的荷载分担,群桩分析采用基于弹性理论的积分方程方法,并通过cut-off方法来反映桩的弹塑性特性,实现群桩基础的弹塑性优化分析,改进了常规弹性分析方法的缺陷。算例分析表明,随着外荷载的不断增加,角桩首先达到极限荷载,对角桩超出极限荷载的部分进行重新分布,继而使得边桩逐渐达到极限承载状态,继续加载直至内桩也达到极限承载状态,从而引起桩筏基础的整体破坏。采用cut-off方法可以改进基础变刚度优化设计,使之与实际情况更为吻合。
In order to solve the problem of optimal design of rigid pile group foundation pile group, the pile load distribution is adjusted by changing the pile length distribution. The pile group analysis uses the integral equation method based on elasticity theory and reflects the pile projectile by the cut-off method Plasticity characteristics of pile group foundation to achieve elasto-plastic optimization analysis of pile group foundation, and improve the defects of conventional elastic analysis method. The case study shows that with the increase of external load, the angle piles reach the ultimate load first and the diagonal piles distribute beyond the limit load, then the edge piles reach the ultimate load state gradually and continue to be loaded until the piles reach the limit Bearing state, resulting in the overall destruction of piled raft foundation. The cut-off method can be used to improve the basic variable stiffness design to make it more consistent with the actual situation.