Small Strain Stiffness Property of Structured Loess
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摘要: 由于存在以粉粒为主的土骨架和大量孔隙形成的架空结构以及粒间胶结作用，原状黄土表现出显著的结构特性。为研究结构性对黄土小应变刚度的影响，以典型的结构性黄土为研究对象，利用固定–自由型Stokoe共振柱试验系统，开展了原状与重塑黄土试样在不同围压下的共振柱试验。结果表明，在小应变范围内，原状与重塑黄土的刚度特性均表现出非线性特征，其剪切模量–剪应变（G-γ）关系可以采用Hardin-Drnevich双曲线模型进行拟合。结构性显著控制黄土的小应变刚度特性，表现在原状土相较于重塑土具有更高的剪切模量、更低的刚度对围压的敏感性。研究还对结构性对黄土小应变刚度的控制作用开展了定量评价，并与包括伦敦黏土、渥太华砂在内的多种黏性土、砂土进行了比较，加深了对结构性黄土力学行为的理解，为相关工程设计提供技术参考。Abstract: Because of the soil skeleton containing dominant silt as well as interparticle cementation, the natural loess behaves in a structured way. To study the influence of structural properties on the small-strain stiffness of loess, resonant column tests were performed on typical natural and remolded loess under different confining pressures. The results showed that both the original and remolded loess exhibit a nonlinear stiffness characteristic within the small strain range and their shear modulus-shear strain (G-γ) relationships can be fitted by the Hardin-Drnevich hyperbolic model. Structural properties were found to significantly control the small-strain stiffness properties of loess, as exemplified by a higher shear modulus and a lower sensitivity of the maximum shear modulus to confining pressure of natural loess compared to the case of remolded soil. In addition, this study quantified the effect of structure on the small strain stiffness of loess and makes comparisons with some well-studied sands and clays (including London clay and Ottawa sand). This research enhanced the understanding of the mechanical behavior of structured loess and can provide technical reference for related engineering design.
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Key words:
- loess /
- structure /
- small strain stiffness /
- shear modulus /
- resonant column
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表 1 本文研究的黄土的物理、力学指标
取样深度/m 比重Gs 密度ρ/(g·cm-3) 含水率w/% 液限wL/% 塑限wp/% 塑性指数Ip/% 结构屈服应力Pc/kPa 孔隙比e0 3.5 2.71 1.55 15.64 34.76 26.47 8.29 100 1.022 
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表 2 共振柱试验试样信息
试样编号 试验对象 初始孔隙比 固结围压/kPa U25 原状土 1.020 25 U50 原状土 1.024 50 U100 原状土 1.022 100 U200 原状土 1.023 200 R25 重塑土 1.020 25 R50 重塑土 1.024 50 R100 重塑土 1.022 100 R200 重塑土 1.023 200
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