小比尺条形基础承载力模型试验的尺寸效应研究

Size effects of small-scale model tests on bearing capacity of strip foundation

开展小比尺模型试验是土力学承载力研究中的重要方法,但小比尺模型的尺寸效应会影响试验的定量结果,导致小比尺试验一般仅能用于定性研究。在饱和砂土地基中开展了20组条形基础承载力的小比尺模型试验,通过改变基础尺寸、埋深以及砂土的密实度研究承载力的变化,进而引入离散元分析方法,采用抗转动模型模拟砂土颗粒的力学行为,对条形基础承载力试验进行模拟,从微观角度揭示小比尺模型试验尺寸效应的来源和对宏观承载力的影响规律。研究结果表明,饱和砂土地基密实度与基础埋深越大,小比尺实试验的尺寸效应越明显,尺寸效应的产生是应力水平变化、破坏模式改变以及渐进破坏程度综合作用的结果。

The small-scale model test is an important method to study the bearing capacity in soil mechanics.However,the size effects of small-scale model will affect its quantitative results,so that the small-scale test can only be used for qualitative researches.In this study,20 groups of small-scale model tests on bearing capacity of strip foundation are carried out in saturated sand foundation.The change of bearing capacity is studied by changing the foundation size,buried depth and compactness of sand.Then the discrete element analysis method is introduced,and the mechanical behavior of sand particles is simulated by rolling the resistance contact model.The bearing capacity tests on the strip foundation are simulated,and the source of the size effects of small-scale model tests and their influences on macroscopic bearing capacity are revealed from a microscopic point of view.The results show that there is a size effect in the small-scale model tests on the saturated sand foundation.The larger the foundation compactness and foundation depth,the more obvious the size effects.The size effects are the result of the combined effects of change of stress level,change of failure mode and degree of progressive failure.