含水率波动状态下公明公路路基土劣化微观机理与本构模型

通过固结排水三轴剪切试验、压汞试验和电镜扫描试验探究含水率波动对公明公路路基土力学特性的影响与其劣化微观机理，基于邓肯-张模型提出了一个能够考虑含水率波动影响的路基土经验本构模型。结果表明：含水率波动使得路基土中、大孔隙增多，同时微裂隙得到发展引起试样结构被分割，导致试样剪切应力-应变关系从应变软化向应变硬化型转变，试样剪缩特性提升、剪切强度降低；含水率波动程度越大，试样剪缩特性越明显，剪切强度则越弱；提出的路基土本构模型的计算结果与试验结果吻合较好，证明了模型的有效性和适用性。

Study on deterioration meso-mechanism and constitutive model of subgrade soil from Gongming road under the fluctuation of water content

Consolidated drained triaxial shear tests, mercury injection tests and electron microscope scanning tests were conducted in this study to investigate the effects of the water content fluctuation on the mechanical properties of soil from the Gongming road and the meso-mechanism of deterioration. Based on the Duncan-Chang model, an empirical constitutive model of the subgrade soil was proposed to consider the effect of water content fluctuation. The results show that the development of pores, macropores and micro-cracks leads to the transformation of soil shear stress-strain relationship from the strain-softening to the strain-hardening, the improvement of soil shear shrinkage characteristics and the decrease of shear strength. With the increase of moisture content fluctuation, the shear shrinkage characteristics of the sample become more obvious, but the shear strength decreases. The calculation results of the proposed constitutive model for the subgrade soil are in good agreement with the test results, which proves the effectiveness and applicability of the model.