This paper studies the effect of loading eccentricity and pile spacing on the ultimate lateral soil resistance of twin-piles using finite element limit analysis and analytical upper bound plasticity methods. Two kinematic mechanisms corresponding to the failure modes produced by the advanced finite element simulations are postulated with different eccentricity and pile spacing cases. Comparisons have shown excellent agreements between the two approaches. A series of parametric studies are then subsequently performed. Numerical results have shown that loading eccentricity considerably affects ultimate lateral soil resistance, leading to a maximum reduction of 50%. In addition, the curve of normalised pile resistance versus pile spacing ratio is dissimilar to that without considering the effect of loading eccentricity. The proposed solutions and failure mechanisms in this study will provide a deepened insight on the performance of twin-pile group under eccentric loads.

本文利用有限元极限分析和解析上限塑性方法研究了加载偏心率和桩间距对双桩极限侧向土阻力的影响。在不同的偏心率和桩间距情况下，假设了与高级有限元模拟产生的失效模式相对应的两种运动机制。比较表明这两种方法之间的一致性非常好。随后进行一系列参数研究。数值结果表明，加载偏心率显着影响最终横向土壤阻力，导致最大减少 50%。此外，归一化桩阻力与桩距比的曲线与不考虑加载偏心率影响的曲线不同。