基于参考压缩线的砂土压缩模型

The Compression Model of Sand Based on Reference Compression Curve

等向压缩线不唯一及V-lgp空间内非线性变化是砂土压缩模型构建过程中存在的两大问题。通过分析砂土的等向压缩曲线变化特征,结合其力学特性提出了与临界状态线在0点相交并与其它等向压缩线在高压下相互汇聚的等向压缩线作为参考压缩线。采用ln(V-Vmin)-(p/pa)ξ空间内线性函数来描述参考压缩线与临界状态线。利用当前体积到参考压缩线的距离构建状态参量并建立修正函数以获取其它体积下的压缩曲线斜率。参考压缩线及弹性变形规律。基于参考压缩线建立的砂土压缩模型不仅表现出砂土在低应力段的小变形特征及高压下的近似线性关系,而且能够描述极限体积附近的低压缩性特征。模型预测与Toyoura砂等向压缩试验及循环压缩试验、弯曲元试验及共振柱试验对比结果表明,提出的砂土压缩模型不仅能够很好地描述Toyoura砂的压缩特性,而且能够较为可靠地预测砂土弹性变形趋势。

There are two major problems in the construction of sand compression model,namely,one is the non-uniqueness of isotropic compression curve and the other is its non-linear variation in V-lgp space.This paper proposed a reference compression curve for all compression curves by analyzing the variation characteristics of isotropic compression curve of sand and considering its mechanical properties.The reference compression curve is an isotropic compression curve intersecting with the critical state line at 0 pressure and converging with other isotropic compression curves under high pressure.It can be described with a linear function in ln(V-Vmin)-(p/pa)ξspace.The slopes of compression curve under other volume can be obtained with a correction function based on the current volume and reference compression curve,and a mathematical function similar to reference compression curve can be used to describe the elastic deformation of sand.The sand compression model based on reference compression curve shows not only the small deformation characteristics of sand in the low stress section and the approximate linear relationship under high pressure,but also the low compressibility characteristics near the minimum volume.Compared with isotropic compression test,cyclic compression test,flexural element test and resonant cylinder test of Toyoura sand,the proposed sand compression model can describe its compression characteristics with satisfactory results,and furthermore,it can predict the elastic deformation pattern of sand more reliably.