Liu Xin, Xu Xinyu, Huang Liang, Wei Xiao, Lan Hengxing
School of Geological Engineering and Geomatics, Chang'an University, Xi'an 710054, China.
Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou, 310058, China.
Sci Rep. 2024 May 29;14(1):12384. doi: 10.1038/s41598-023-42248-1.
Compared with conventional soils, such as sand and clay, little knowledge on the coefficient of lateral earth pressure at-rest (K) has been established for loess in the current literature. This paper presents an experimental investigation on K of compacted loess and the associated impacts on undrained shear behaviour. By adopting a K consolidation module in the triaxial system, the K stress state for loess samples was achieved through a unique feedback control. During the K consolidation, the deviatoric stress (q) increases progressively with the premise that the volumetric strain (ε) of the sample equals to the axial strain (ε). The results show that the K value of compacted loess is in a range of 0.28 to 0.53, which is dependent on the packing density and the clay content. A distinguishable decrease of K was found in the course of K consolidation for the loosely compacted loess sample, whereas a similar trend was not observed in the dense sample. In the undrained shear stage, all loess specimens revealed contractive response in the stress path (q-p') diagram, which can be quantified by a modified collapsibility index (I). The index is consistently higher for the K consolidated loess samples than for the isotropic ones. The experimental results indicate a strong impact of the initial stress state on the shear behaviour of compacted loess.
与砂和黏土等传统土壤相比，目前文献中关于黄土静止土压力系数（K）的研究较少。本文对压实黄土的K值及其对不排水剪切特性的影响进行了试验研究。通过在三轴系统中采用K固结模块，通过独特的反馈控制实现了黄土试样的K应力状态。在K固结过程中，在试样的体积应变（ε）等于轴向应变（ε）的前提下，偏应力（q）逐渐增加。结果表明，压实黄土的K值在0.28至0.53范围内，这取决于压实密度和黏土含量。在松散压实黄土试样的K固结过程中，发现K值有明显下降，而密实试样中未观察到类似趋势。在不排水剪切阶段，所有黄土试样在应力路径（q-p'）图中均表现出剪缩响应，这可以通过修正的湿陷性指数（I）来量化。K固结黄土试样的该指数始终高于各向同性试样。试验结果表明初始应力状态对压实黄土的剪切特性有强烈影响。
