水平循环荷载下饱和软土地基单桩基础模型试验研究

通过水平循环加载装置对某工程饱和软土地基单桩基础开展了水平循环荷载模型试验研究，探讨单桩基础的水平承载力和循环变形特性。结果表明:①桩周地基土体有不同形态的裂缝，桩周土软化后上部地基土会丧失部分承载力，危及桩基及上部结构的安全；②随着循环次数增加，桩身位移逐渐增大，建立了一种新的桩基位移预测计算模型，可根据该模型推算循环荷载条件下的桩基位移；③桩身最大弯矩值也随着循环加载次数的增加而显著增大，最大弯矩点出现于桩身的（3～4） D深度处。建议在设计规范中应充分考虑桩身弯矩的循环累积增大效应，在设计时应有足够的安全系数。

Experimental Study on Single Pile Foundation Model in Saturated Soft Soil Foundation under Lateral Cyclic Loading

A lateral cyclic loading model test study on single pile foundation of saturated soft soil foundation of a project was conducted by using lateral cyclic loading device, discussing the lateral bearing capacity and cyclic deformation characteristics of the single pile foundation. The test results indicate that:① many cracks with different forms has formed on the foundation soil around the pile and the upper soil lost partial bearing capacity due to the soften soil around the pile, which would endanger the pile foundation and upper structure; ② the pile displacement and the pile accumulated deformation would increase with the repeated lateral loading. A new pile displacement forecast model was eastablished which can predict the pile displacement under different kinds of cyclic loading. ③ The maximum pile bending moment is increased significantly with the repeated cyclic loading, the maximum bending moment point is in (3~4)D depth of the pile. Therefore, the accumulated increasing effect of pile bending moment should be carefully considered during design and calculation, reserving sufficient safety factor in design.