水-岩相互作用下华南红层软岩力学特性

Mechanical properties of red-bed soft rocks in South China under water-rock interaction

为研究红层软岩的水-岩相互作用,开展了不同含水率红层软岩的三轴压缩试验,分析了含水率对力学特性、破坏形式、微观结构和损伤机制的影响,构建了含水红层软岩的统计损伤本构模型。研究结果表明:随含水率的升高,红层软岩的峰值应变呈线性递增,峰值强度和弹性模量分别呈线性和指数函数递减;含水率对红层软岩的破坏模式产生明显影响,含水率较低时的破坏形式为剪切破坏,随着含水率的增加,破坏形式向剪切-张拉复合型破坏转变。在水-岩相互作用下,华南红层软岩的孔隙颗粒物相互吸附,形成片状结构;在饱水状态下,片状和鳞状结构进一步增多,整体结构变得更加松散破碎。考虑水-岩作用,引入损伤修正系数对本构模型进行改进,改进后的统计损伤本构模型计算结果与试验结果一致,能较好地描述水岩作用对红层软岩力学性质的影响。

In order to study the water-rock interaction of red-bed soft rock,triaxial compression tests of red-bed soft rock with different water content were carried out,the effects of water content on mechanical properties,failure forms,microstructure and damage mechanism were analyzed,and the statistical damage constitutive model of red-bed soft rock with water content was constructed.The results show that the peak strain increases linearly with the increase of water content,and the peak strength and elastic modulus decrease linearly and exponentially respectively.Water content has obvious influence on the failure mode of red-bed soft rock.When the water content is low,the failure mode is shear failure.With the increase of water content,the failure mode changes to shear-tension composite failure.Under the water-rock interaction,the pore particles of the soft rocks in the red-bed of South China are adsorbed to each other and form a sheet structure.In the saturated state,the lamellar and scaly structures further increase,and the overall structure becomes more loose and fragmented.Considering the water-rock interaction,the damage correction coefficient is introduced to improve the constitutive model.The calculated results of the improved statistical damage constitutive model are consistent with the experimental results,which can better describe the influence of water-rock interaction on the mechanical properties of red layer soft rock.