基于散体介质宏微观力学分析,通过引入平均投影固体路径和真应力两个物理量,建立了砂土原生各向异性强度准则。当应力主方向和组构主方向重合或接近时,砂土强度显著提高。在此基础上,推导了具有原生各向异性的地层的土压力计算公式,并对朗肯土压力系数进行了修正。分析了原生各向异性和内摩擦角对墙后土压力的影响。理论预测结果与试验数据对比分析表明:原生各向异性的大小和方向均对土压力产生影响,当各向异性方向改变时土压力的变化规律不同;随着内摩擦角的增大,各向异性和各向同性条件下的主动土压力强度都逐渐减小,当原生各向异性方向改变时,这一规律同样适用。文中建立的土压力计算方法考虑了地层的各向异性影响且形式简洁,便于工程应用。
Abstract
On the basis of macro-and-micro-mechanical analysis of granular media,the inherent anisotropic strength criterion of sand is established by introducing two physical quantities:the mean projected solid path and the true stress.When the principal direction of stress coincides with or approaches the principal direction of fabric,the strength of sand increases significantly.On this basis,the calculation formula of earth pressure in the stratum with inherent anisotropy is deduced,and the Rankine's earth pressure coefficient is modified.The effects of inherent anisotropy and internal friction angle on earth pressure behind retaining wall are analyzed.The comparison between theoretical prediction results and experimental data shows that the magnitude and direction of inherent anisotropy both affect the earth pressure,and the variation law of earth pressure is different when the direction of anisotropy changes.With the increase of internal friction angle,the strength of active earth pressure under anisotropic or isotropic conditions decreases gradually,which is also true when the direction of inherent anisotropy changes.The earth pressure calculation method established in this paper considers the influence of anisotropy in the stratum,and is convenient for engineering application because of its concise form.
关键词
原生各向异性 /
强度准则 /
土压力 /
挡土墙 /
砂土
Key words
inherent anisotropy /
failure criterion /
earth pressure /
retaining wall /
sand
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基金
国家自然科学基金项目(5210080417)
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