边坡全风化花岗岩抗剪强度的浸水时间效应研究

The study of the effect of the water time effect of the shear strength of the fully weathering granite

为了揭示公路边坡工程中全风化花岗岩工程特性的演变规律,对原状全风化花岗岩试样开展力学测试和微观分析,通过开展不同浸水时间(0 h~180 h)过程中的三轴抗剪强度测试,获得三轴应力条件下的应力与应变的关系,分析全风化花岗岩抗剪强度指标特点,结合微观图像揭示全风化花岗岩微结构损伤机理。结果表明:在4种围压条件下,试验测得的全风化花岗岩应力-应变关系均为硬化曲线特征,峰值强度随浸水时间推移而减损;对比不同浸水时程下的抗剪强度指标,发现全风化花岗岩软化程度随浸水时间增长有明显升高趋势,强度软化变量与浸水时间呈对数函数关系;微观图像表明岩土颗粒在浸水过程中逐渐松散化,微孔隙逐渐连通,强度因此发生衰减。

In order to reveal the evolution law of engineering characteristics of fully weathered granite in highway slope engineering,mechanical testing and microscopic analysis were carried out on samples of intact fully weathered granite.The relationship between stress and strain under triaxial stress was obtained by conducting triaxial shear strength tests during different immersion times(0 h~180 h),and the characteristics of shear strength indexes of fully weathered granite were analyzed.Combined with microscopic images,the damage mechanism of microstructures of fully weathered granite is revealed.The results show that under the four confining pressure conditions,the stress-strain relationship of the weathered granite is characterized by hardening curve,and the peak strength decreases with the passage of soaking time.By comparing the shear strength indexes under different immersion time,it is found that the softening degree of the weathered granite has an obvious increasing trend with the increase of immersion time,and the strength softening variable is a logarithmic function with the immersion time.The microscopic images show that the rock and soil particles are gradually loosened and the micropores are gradually connected during the immersion process,and the strength attenuates accordingly.